Lint the code.

Add support for Python 3.9.

33 files changed, 752 insertions, 422 deletions

diff --git a/src/zope/security/__init__.py b/src/zope/security/__init__.py
index 5f079f6..d6f39f4 100644
--- a/src/zope/security/__init__.py
+++ b/src/zope/security/__init__.py
@@ -21,4 +21,3 @@ from zope.security.checker import canWrite, canAccess
 # zope.location's LocationProxy as soon someone uses security proxies by
 # importing zope.security.proxy:
 import zope.security.decorator
-
diff --git a/src/zope/security/_compat.py b/src/zope/security/_compat.py
index 07b3a02..6f7dc0a 100644
--- a/src/zope/security/_compat.py
+++ b/src/zope/security/_compat.py
@@ -22,7 +22,7 @@ py_impl = getattr(platform, 'python_implementation', lambda: None)
 PYPY = py_impl() == 'PyPy'
 PURE_PYTHON = os.environ.get('PURE_PYTHON', PYPY)
 
-if sys.version_info[0] < 3: # pragma: no cover
+if sys.version_info[0] < 3:  # pragma: no cover
 
     CLASS_TYPES = (type, types.ClassType)
     _BUILTINS = '__builtin__'
@@ -30,7 +30,7 @@ if sys.version_info[0] < 3: # pragma: no cover
     PYTHON3 = False
     PYTHON2 = True
 
-else: # pragma: no cover
+else:  # pragma: no cover
 
     CLASS_TYPES = (type,)
     _BUILTINS = 'builtins'
diff --git a/src/zope/security/_definitions.py b/src/zope/security/_definitions.py
index 929823c..070a345 100644
--- a/src/zope/security/_definitions.py
+++ b/src/zope/security/_definitions.py
@@ -20,10 +20,12 @@ from zope.security import interfaces
 
 thread_local = threading.local()
 
+
 @zope.interface.implementer(interfaces.ISystemPrincipal)
 class SystemUser(object):
     id = u'zope.security.management.system_user'
     title = u'System'
     description = u''
 
+
 system_user = SystemUser()
diff --git a/src/zope/security/adapter.py b/src/zope/security/adapter.py
index 661e49d..c8c44b6 100644
--- a/src/zope/security/adapter.py
+++ b/src/zope/security/adapter.py
@@ -18,6 +18,7 @@ from zope.security.checker import ProxyFactory
 from zope.security.proxy import removeSecurityProxy
 from zope.location import ILocation, LocationProxy
 
+
 def assertLocation(adapter, parent):
     """
     Assert locatable adapters.
@@ -59,6 +60,7 @@ class LocatingTrustedAdapterFactory(object):
     ``__parent__`` is None, we set the ``__parent__`` to the adapter's
     context.
     """
+
     def __init__(self, factory):
         self.factory = factory
         self.__name__ = factory.__name__
diff --git a/src/zope/security/checker.py b/src/zope/security/checker.py
index 2dbc4e1..67723e8 100644
--- a/src/zope/security/checker.py
+++ b/src/zope/security/checker.py
@@ -36,14 +36,16 @@ You can set the environment variable ``ZOPE_WATCH_CHECKERS`` before
 this module is imported to get additional security checker debugging
 output on the standard error.
 
-Setting ``ZOPE_WATCH_CHECKERS`` to 1 will display messages about unauthorized or
-forbidden attribute access.  Setting it to a larger number will also display
+Setting ``ZOPE_WATCH_CHECKERS`` to 1 will display messages about unauthorized
+or forbidden attribute access.  Setting it to a larger number will also display
 messages about granted attribute access.
 
 Note that the ``ZOPE_WATCH_CHECKERS`` mechanism may eventually be
 replaced with a more general security auditing mechanism.
 
-.. seealso:: :class:`CheckerLoggingMixin`, :class:`WatchingChecker`, :class:`WatchingCombinedChecker`
+.. seealso:: :class:`CheckerLoggingMixin`
+.. seealso:: :class:`WatchingChecker`
+.. seealso:: :class:`WatchingCombinedChecker`
 
 API
 ===
@@ -88,16 +90,16 @@ from zope.security.proxy import getChecker
 
 try:
     from zope.exceptions import DuplicationError
-except ImportError: # pragma: no cover
+except ImportError:  # pragma: no cover
     class DuplicationError(Exception):
         """A duplicate registration was attempted"""
 
 WATCH_CHECKERS = 0
 
-if os.environ.get('ZOPE_WATCH_CHECKERS'):
+if os.environ.get('ZOPE_WATCH_CHECKERS'):  # pragma: no cover
     try:
         WATCH_CHECKERS = int(os.environ.get('ZOPE_WATCH_CHECKERS'))
-    except ValueError: # pragma: no cover
+    except ValueError:
         WATCH_CHECKERS = 1
 
 
@@ -129,12 +131,14 @@ def ProxyFactory(object, checker=None):
 
     return Proxy(object, checker)
 
+
 directlyProvides(ProxyFactory, ISecurityProxyFactory)
 
 # This import represents part of the API for the proxy module
 from . import proxy
 proxy.ProxyFactory = ProxyFactory
 
+
 def canWrite(obj, name):
     """Check whether the interaction may write an attribute named name on obj.
 
@@ -169,6 +173,7 @@ def canWrite(obj, name):
     # should be passed through uncaught, as they indicate programmer error
     return True
 
+
 def canAccess(obj, name):
     """Check whether the interaction may access an attribute named name on obj.
 
@@ -187,6 +192,7 @@ def canAccess(obj, name):
     # indicates a programming or configuration error
     return True
 
+
 @implementer(INameBasedChecker)
 class CheckerPy(object):
     """
@@ -230,7 +236,6 @@ class CheckerPy(object):
         if self.set_permissions:
             return self.set_permissions.get(name)
 
-
     def check_setattr(self, object, name):
         'See IChecker'
         if self.set_permissions:
@@ -240,9 +245,9 @@ class CheckerPy(object):
 
         if permission is not None:
             if permission is CheckerPublic:
-                return # Public
+                return  # Public
             if thread_local.interaction.checkPermission(permission, object):
-                return # allowed
+                return  # allowed
             else:
                 __traceback_supplement__ = (TracebackSupplement, object)
                 raise Unauthorized(object, name, permission)
@@ -255,7 +260,7 @@ class CheckerPy(object):
         permission = self.get_permissions.get(name)
         if permission is not None:
             if permission is CheckerPublic:
-                return # Public
+                return  # Public
             if thread_local.interaction.checkPermission(permission, object):
                 return
             else:
@@ -268,7 +273,7 @@ class CheckerPy(object):
             __traceback_supplement__ = (TracebackSupplement, object)
             raise ForbiddenAttribute(name, object)
 
-    check_getattr = check # 'See IChecker'
+    check_getattr = check  # 'See IChecker'
 
     def proxy(self, value):
         'See IChecker'
@@ -281,7 +286,9 @@ class CheckerPy(object):
                 return value
 
         return Proxy(value, checker)
-Checker = CheckerPy # in case no C optimizations
+
+
+Checker = CheckerPy  # in case no C optimizations
 
 
 # Helper class for __traceback_supplement__
@@ -296,19 +303,19 @@ class TracebackSupplement(object):
             cls = self.obj.__class__
             if hasattr(cls, "__module__"):
                 s = "%s.%s" % (cls.__module__, cls.__name__)
-            else: # pragma: no cover XXX
+            else:  # pragma: no cover XXX
                 s = str(cls.__name__)
             result.append("   - class: " + s)
-        except: # pragma: no cover XXX
+        except:  # pragma: no cover # noqa: E722 do not use bare 'except'
             pass
         try:
             cls = type(self.obj)
             if hasattr(cls, "__module__"):
                 s = "%s.%s" % (cls.__module__, cls.__name__)
-            else: # pragma: no cover XXX
+            else:  # pragma: no cover XXX
                 s = str(cls.__name__)
             result.append("   - type: " + s)
-        except: # pragma: no cover XXX
+        except:  # pragma: no cover # noqa: E722 do not use bare 'except'
             pass
         return "\n".join(result)
 
@@ -322,7 +329,7 @@ class Global(object):
     """
 
     def __init__(self, name, module=None):
-        if module is None: # pragma: no cover XXX
+        if module is None:  # pragma: no cover XXX
             module = sys._getframe(1).f_locals['__name__']
 
         self.__name__ = name
@@ -344,7 +351,7 @@ CP_HACK_XXX = CheckerPublic
 # XXX: This means that we can't directly document it with
 # sphinx because issubclass() will fail.
 d = {}
-CheckerPublic = Proxy(CheckerPublic, Checker(d)) # XXX uses CheckerPy
+CheckerPublic = Proxy(CheckerPublic, Checker(d))  # XXX uses CheckerPy
 d['__reduce__'] = CheckerPublic
 d['__module__'] = CheckerPublic
 del d
@@ -353,6 +360,7 @@ del d
 # granted to __reduce__. We might want to bother to prevent this in
 # general and only allow it in this specific case.
 
+
 def NamesChecker(names=(), permission_id=CheckerPublic, **__kw__):
     """Return a checker that grants access to a set of names.
 
@@ -371,6 +379,7 @@ def NamesChecker(names=(), permission_id=CheckerPublic, **__kw__):
 
     return Checker(data)
 
+
 def InterfaceChecker(interface, permission_id=CheckerPublic, **__kw__):
     """
     Create a :func:`NamesChecker` for all the names defined in the *interface*
@@ -378,6 +387,7 @@ def InterfaceChecker(interface, permission_id=CheckerPublic, **__kw__):
     """
     return NamesChecker(interface.names(all=True), permission_id, **__kw__)
 
+
 def MultiChecker(specs):
     """
     Create a checker from a sequence of specifications
@@ -415,6 +425,7 @@ def MultiChecker(specs):
 
     return Checker(data)
 
+
 def selectCheckerPy(object):
     """Get a checker for the given object
 
@@ -428,13 +439,13 @@ def selectCheckerPy(object):
 
     # TODO: we really need formal proxy introspection
 
-    #if type(object) is Proxy:
+    # if type(object) is Proxy:
     #    # Is this already a security proxy?
     #    return None
 
     checker = _getChecker(type(object), _defaultChecker)
 
-    #checker = _getChecker(getattr(object, '__class__', type(object)),
+    # checker = _getChecker(getattr(object, '__class__', type(object)),
     #                      _defaultChecker)
 
     if checker is NoProxy:
@@ -447,12 +458,18 @@ def selectCheckerPy(object):
             return None
 
     return checker
-selectChecker = selectCheckerPy # in case no C optimizations
+
+
+selectChecker = selectCheckerPy  # in case no C optimizations
+
 
 def getCheckerForInstancesOf(class_):
     return _checkers.get(class_)
 
+
 DEFINABLE_TYPES = CLASS_TYPES + (types.ModuleType,)
+
+
 def defineChecker(type_, checker):
     """Define a checker for a given type of object
 
@@ -466,9 +483,11 @@ def defineChecker(type_, checker):
         raise DuplicationError(type_)
     _checkers[type_] = checker
 
+
 def undefineChecker(type_):
     del _checkers[type_]
 
+
 NoProxy = object()
 
 # _checkers is a mapping.
@@ -488,13 +507,13 @@ _available_by_default = []
 
 # Get optimized versions
 _c_available = not PURE_PYTHON
-if _c_available:
+if _c_available:  # pragma: no cover
     try:
         import zope.security._zope_security_checker
-    except (ImportError, AttributeError): # pragma: no cover PyPy / PURE_PYTHON
+    except (ImportError, AttributeError):
         _c_available = False
 
-if _c_available:
+if _c_available:  # pragma: no cover
     from zope.security._zope_security_checker import _checkers, selectChecker
     from zope.security._zope_security_checker import NoProxy, Checker
     from zope.security._zope_security_checker import _defaultChecker
@@ -504,6 +523,7 @@ if _c_available:
 
 _getChecker = _checkers.get
 
+
 @implementer_if_needed(IChecker)
 class CombinedChecker(Checker):
     """A checker that combines two other checkers in a logical-or fashion.
@@ -527,7 +547,7 @@ class CombinedChecker(Checker):
     +--------------------+--------------------+-------------------------------------+
     | ForbiddenAttribute | ForbiddenAttribute | ForbiddenAttribute                  |
     +--------------------+--------------------+-------------------------------------+
-    """
+    """  # noqa: E501 line too long
 
     def __init__(self, checker1, checker2):
         """Create a combined checker."""
@@ -544,7 +564,8 @@ class CombinedChecker(Checker):
         except ForbiddenAttribute:
             self._checker2.check(object, name)
         except Unauthorized as unauthorized_exception:
-            try: self._checker2.check(object, name)
+            try:
+                self._checker2.check(object, name)
             except ForbiddenAttribute:
                 raise unauthorized_exception
 
@@ -562,6 +583,7 @@ class CombinedChecker(Checker):
             except ForbiddenAttribute:
                 raise unauthorized_exception
 
+
 class CheckerLoggingMixin(object):
     """
     Debugging mixin for checkers.
@@ -649,6 +671,8 @@ class WatchingChecker(CheckerLoggingMixin, Checker):
     module is imported.
     """
     verbosity = WATCH_CHECKERS
+
+
 class WatchingCombinedChecker(CombinedChecker, WatchingChecker):
     """
     A checker that will perform verbose logging. This will be set
@@ -657,7 +681,8 @@ class WatchingCombinedChecker(CombinedChecker, WatchingChecker):
     """
     verbosity = WATCH_CHECKERS
 
-if WATCH_CHECKERS: # pragma: no cover
+
+if WATCH_CHECKERS:  # pragma: no cover
     # When we make these the default, we also need to be sure
     # to update the _defaultChecker's type (if it's not the C
     # extension) so that selectCheckerPy can properly recognize
@@ -669,9 +694,11 @@ if WATCH_CHECKERS: # pragma: no cover
     if not _c_available:
         _defaultChecker.__class__ = Checker
 
+
 def _instanceChecker(inst):
     return _checkers.get(inst.__class__, _defaultChecker)
 
+
 def moduleChecker(module):
     """
     Return the :class:`zope.security.interfaces.IChecker` defined for the
@@ -713,11 +740,13 @@ _setChecker = NamesChecker([
     '__le__', '__ge__',
 ])
 
+
 class _BasicTypes(dict):
     """Basic Types Dictionary
 
     Make sure that checkers are really updated, when a new type is added.
     """
+
     def __setitem__(self, name, value):
         dict.__setitem__(self, name, value)
         _checkers[name] = value
@@ -734,6 +763,7 @@ class _BasicTypes(dict):
         dict.update(self, d)
         _checkers.update(d)
 
+
 _basic_types = {
     object: NoProxy,
     int: NoProxy,
@@ -742,7 +772,7 @@ _basic_types = {
     type(None): NoProxy,
     str: NoProxy,
     bytes: NoProxy,
-    Message: NoProxy, # Messages are immutable, so it's okay
+    Message: NoProxy,  # Messages are immutable, so it's okay
     bool: NoProxy,
     datetime.timedelta: NoProxy,
     datetime.datetime: NoProxy,
@@ -750,10 +780,10 @@ _basic_types = {
     datetime.time: NoProxy,
     datetime.tzinfo: NoProxy,
 }
-if PYTHON2:
-    _basic_types[long] = NoProxy
-    _basic_types[unicode] = NoProxy
-else: # pragma: no cover
+if PYTHON2:  # pragma: no cover
+    _basic_types[long] = NoProxy  # noqa: F821 undefined name 'long'
+    _basic_types[unicode] = NoProxy  # noqa: F821 undefined name 'unicode'
+else:
     _basic_types[type({}.values())] = NoProxy
     _basic_types[type({}.keys())] = NoProxy
     _basic_types[type({}.items())] = NoProxy
@@ -784,26 +814,29 @@ BasicTypes_examples = {
     Message: Message('message', domain='hello')
 }
 
-if PYTHON2:
-    BasicTypes_examples[unicode] = u'uabc'
-    BasicTypes_examples[long] = long(65536)
+if PYTHON2:  # pragma: no cover
+    BasicTypes_examples[unicode] = u'uabc'  # noqa: F821 undefined name
+    BasicTypes_examples[long] = long(65536)  # noqa: F821 undefined name
 
 
 class _Sequence(object):
     def __len__(self):
         raise NotImplementedError()
+
     def __getitem__(self, i):
         raise NotImplementedError()
 
+
 _Declaration_checker = InterfaceChecker(
     IDeclaration,
     _implied=CheckerPublic,
     subscribe=CheckerPublic,
     unsubscribe=CheckerPublic,
     __call__=CheckerPublic,
-    )
+)
+
 
-def f(): # pragma: no cover
+def f():  # pragma: no cover
     yield f
 
 
@@ -837,7 +870,7 @@ _default_checkers = {
                                    'max', 'min', 'normalize',
                                    'quantize', 'remainder_near',
                                    'same_quantum', 'sqrt',
-                                   'to_eng_string', 'to_integral' ]),
+                                   'to_eng_string', 'to_integral']),
 
     # YAGNI: () a rock
     tuple: NamesChecker(['__getitem__', '__getslice__', '__add__', '__radd__',
@@ -851,8 +884,8 @@ _default_checkers = {
     types.BuiltinMethodType: _callableChecker,
     type: _typeChecker,
     types.ModuleType: lambda module: _checkers.get(module, _namedChecker),
-    type(iter([])): _iteratorChecker, # Same types in Python 2.2.1,
-    type(iter(())): _iteratorChecker, # different in Python 2.3.
+    type(iter([])): _iteratorChecker,  # Same types in Python 2.2.1,
+    type(iter(())): _iteratorChecker,  # different in Python 2.3.
     type(iter({})): _iteratorChecker,
     type(iter(set())): _iteratorChecker,
     type(iter(_Sequence())): _iteratorChecker,
@@ -875,7 +908,7 @@ _default_checkers = {
     zope.interface.declarations.Declaration: _Declaration_checker,
     abc.ABCMeta: _typeChecker,
 }
-if PYTHON2:
+if PYTHON2:  # pragma: no cover
     _default_checkers[types.ClassType] = _typeChecker
     _default_checkers[types.InstanceType] = _instanceChecker
     # slot description
@@ -884,6 +917,7 @@ if PYTHON2:
     _default_checkers[type({}.iterkeys())] = _iteratorChecker
     _default_checkers[type({}.itervalues())] = _iteratorChecker
 
+
 def _fixup_dictlike(dict_type):
     empty_dict = dict_type()
     populated_dict = dict_type({1: 2})
@@ -898,20 +932,24 @@ def _fixup_dictlike(dict_type):
             if iter_type not in _default_checkers:
                 _default_checkers[iter_type] = _iteratorChecker
 
+
 def _fixup_odict():
     # OrderedDicts have three different implementations: Python 2 (pure
     # python, returns generators and lists), Python <=3.4 (pure Python,
     # uses view classes) and CPython 3.5+ (implemented in C). These should
     # all be iterable.
     from collections import OrderedDict
-    _fixup_dictlike(OrderedDict)
+    # The `_fixup_dictlike` is detected as undefined because it is deleted
+    # later on but this function is called beforehand:
+    _fixup_dictlike(OrderedDict)  # noqa: F821 undefined name '_fixup_dictlike'
+
 
 _fixup_odict()
 del _fixup_odict
 
 try:
-    import BTrees
-except ImportError: # pragma: no cover
+    import BTrees  # noqa: F401 'BTrees' imported but unused
+except ImportError:  # pragma: no cover
     pass
 else:
     # The C implementation of BTree.items() is its own iterator
@@ -934,13 +972,16 @@ else:
             for family_name in ('family32', 'family64'):
                 family = getattr(BTrees, family_name)
                 btree = getattr(family, name).BTree
-                _fixup_dictlike(btree)
+                # The `_fixup_dictlike` is detected as undefined because it is
+                # deleted later on but this function is called beforehand:
+                _fixup_dictlike(btree)  # noqa: F821 undefined name
 
     _fixup_btrees()
     del _fixup_btrees
 
 del _fixup_dictlike
 
+
 def _fixup_zope_interface():
     # Make sure the provided and implementedBy objects
     # can be iterated.
@@ -948,7 +989,8 @@ def _fixup_zope_interface():
     # we use NoProxy to be sure that the results (of iteration or not) are not
     # proxied. On Python 2, these objects are builtin and don't go through the
     # checking process at all, much like BTrees, so NoProxy is necessary for
-    # compatibility. On Python 3, prior to this, iteration was simply not allowed.
+    # compatibility. On Python 3, prior to this, iteration was simply not
+    # allowed.
     from zope.interface import providedBy
     from zope.interface import alsoProvides
 
@@ -959,11 +1001,10 @@ def _fixup_zope_interface():
         pass
 
     @implementer(I1)
-    class O(object):
+    class Obj(object):
         pass
 
-    o = O()
-
+    o = Obj()
 
     # This will be athe zope.interface.implementedBy from the class
     # a zope.interface.declarations.Implements
@@ -973,6 +1014,7 @@ def _fixup_zope_interface():
     # This will be the zope.interface.Provides from the instance
     _default_checkers[type(providedBy(o))] = NoProxy
 
+
 _fixup_zope_interface()
 del _fixup_zope_interface
 
@@ -998,8 +1040,10 @@ def _fixup_itertools():
         _default_checkers[type_grouper] = _iteratorChecker
 
     # There are also many other custom types in itertools that need the
-    # same treatment. See a similar list in test_checker.py:test_itertools_checkers
-    pred = lambda x: x
+    # same treatment. See a similar list in
+    # test_checker.py:test_itertools_checkers
+    def pred(x):
+        return x
     iterable = (1, 2, 3)
     pred_iterable = (pred, iterable)
     missing_in_py3 = {'ifilter', 'ifilterfalse', 'imap',
@@ -1034,7 +1078,8 @@ def _fixup_itertools():
             func = getattr(itertools, func)
         except AttributeError:
             assert func in missing, "Expected %s but not found" % (func,)
-            continue # pragma: no cover This is hit on Python 2, but it doesn't always show
+            # The following line is hit on PY2, but it doesn't always show:
+            continue  # pragma: no cover
 
         result = func(*args)
         if func == itertools.tee:
@@ -1043,19 +1088,22 @@ def _fixup_itertools():
         if tresult not in _default_checkers:
             _default_checkers[tresult] = _iteratorChecker
 
+
 _fixup_itertools()
 del _fixup_itertools
 
+
 def _clear():
     _checkers.clear()
     _checkers.update(_default_checkers)
     _checkers.update(BasicTypes)
 
+
 _clear()
 
 try:
     from zope.testing.cleanup import addCleanUp
-except ImportError: # pragma: no cover
+except ImportError:  # pragma: no cover
     pass
 else:
     addCleanUp(_clear)
diff --git a/src/zope/security/decorator.py b/src/zope/security/decorator.py
index 82ae6e2..dfd6fc7 100644
--- a/src/zope/security/decorator.py
+++ b/src/zope/security/decorator.py
@@ -30,6 +30,7 @@ from zope.security.proxy import getChecker
 class DecoratedSecurityCheckerDescriptor(object):
     """Descriptor for a Decorator that provides a decorated security checker.
     """
+
     def __get__(self, inst, cls=None):
         if inst is None:
             return self
@@ -58,7 +59,7 @@ class DecoratedSecurityCheckerDescriptor(object):
 
 
 class SecurityCheckerDecoratorBase(ProxyBase):
-    """Base class for a proxy that provides additional security declarations."""
+    """Base class for proxy that provides additional security declarations."""
 
     __Security_checker__ = DecoratedSecurityCheckerDescriptor()
 
diff --git a/src/zope/security/examples/sandbox.py b/src/zope/security/examples/sandbox.py
index 8a17984..eb6499f 100644
--- a/src/zope/security/examples/sandbox.py
+++ b/src/zope/security/examples/sandbox.py
@@ -13,13 +13,15 @@
 ##############################################################################
 """A small sandbox application.
 """
-import time, random
+import time
+import random
 
 from zope.interface import Interface, implementer
 
+
 class IAgent(Interface):
     """A player/agent in the world.
-    
+
     The agent represents an autonomous unit, that lives in various
     homes/sandboxes and accesses services present at the sandboxes. Agents are
     imbued with a sense of wanderlust and attempt to find new homes after a
@@ -40,7 +42,7 @@ class IAgent(Interface):
 
 class IService(Interface):
     """Marker to designate some form of functionality.
-    
+
     Services are available from sandboxes, examples include time service,
     agent discovery, and sandbox discovery.
     """
@@ -63,20 +65,21 @@ class ISandbox(Interface):
 
 
 class SandboxError(Exception):
-    """A sandbox error is thrown, if any action could not be performed.""" 
+    """A sandbox error is thrown, if any action could not be performed."""
     pass
 
 
 class Identity(object):
     """Mixin for pretty printing and identity method"""
+
     def __init__(self, id, *args, **kw):
         self.id = id
 
     def getId(self):
         return self.id
 
-    def __str__ (self):
-        return "<%s> %s"%(str(self.__class__.__name__), str(self.id))
+    def __str__(self):
+        return "<%s> %s" % (str(self.__class__.__name__), str(self.id))
 
     __repr__ = __str__
 
@@ -124,92 +127,109 @@ class Sandbox(Identity):
 
     def getAgentIds(self):
         return self._agents.keys()
+
     def getAgents(self):
         return self._agents.values()
+
     def getServiceIds(self):
         return self._services.keys()
+
     def getService(self, sid):
         return self._services.get(sid)
+
     def getHome(self):
         return self
 
-
     def addAgent(self, agent):
-        if not self._agents.has_key(agent.getId()) \
-           and IAgent.providedBy(agent):
-            self._agents[agent.getId()]=agent
+        if agent.getId() not in self._agents \
+                and IAgent.providedBy(agent):
+            self._agents[agent.getId()] = agent
             agent.setHome(self)
         else:
-            raise SandboxError("couldn't add agent %s"%agent)
+            raise SandboxError("couldn't add agent %s" % agent)
 
     def addService(self, service):
 
-        if not self._services.has_key(service.getId()) \
-           and IService.providedBy(service):
-            self._services[service.getId()]=service
+        if not service.getId() in self._services \
+                and IService.providedBy(service):
+            self._services[service.getId()] = service
             service.setHome(self)
         else:
-            raise SandboxError("couldn't add service %s"%service)
+            raise SandboxError("couldn't add service %s" % service)
 
     def transportAgent(self, agent, destination):
-        if self._agents.has_key(agent.getId()) \
-            and destination is not self \
-            and ISandbox.providedBy(destination):
+        if agent.getId() in self._agents \
+                and destination is not self \
+                and ISandbox.providedBy(destination):
             destination.addAgent(agent)
             del self._agents[agent.getId()]
         else:
-            raise SandboxError("couldn't transport agent %s to %s"%(
+            raise SandboxError("couldn't transport agent %s to %s" % (
                 agent, destination)
-                               )
+            )
+
 
 @implementer(IService)
 class Service(object):
     def getId(self):
         return self.__class__.__name__
+
     def setHome(self, home):
         self._home = home
+
     def getHome(self):
         return getattr(self, '_home')
 
+
 class HomeDiscoveryService(Service):
     """
     returns the ids of available agent homes
     """
+
     def getAvailableHomes(self):
         return _homes.keys()
 
+
 class AgentDiscoveryService(Service):
     """
     returns the agents available at a given home
     """
+
     def getLocalAgents(self, home):
         return home.getAgents()
 
+
 class TimeService(Service):
     """
     returns the local time
     """
+
     def getTime(self):
         return time.time()
 
+
 default_service_factories = (
     HomeDiscoveryService,
     AgentDiscoveryService,
     TimeService
-    )
+)
+
 
 def action_find_homes(agent, home):
     home_service = home.getService('HomeDiscoveryService')
     return home_service.getAvailableHomes()
 
+
 def action_find_neighbors(agent, home):
     agent_service = home.getService('AgentDiscoveryService')
     return agent_service.getLocalAgents(home)
 
+
 def action_find_time(agent, home):
     time_service = home.getService('TimeService')
     return time_service.getTime()
 
+
 class TimeGenerator(object):
     """Represents the passage of time in the agent simulation.
 
@@ -238,7 +258,7 @@ class TimeGenerator(object):
                 except Exception as e:
                     print('-- Exception --')
                     print('"%s" in "%s" not allow to "%s"'
-                            % (a, h, a._action.__name__))
+                          % (a, h, a._action.__name__))
                     print(e)
                     print()
                 self.teardownAgent(a)
@@ -253,7 +273,8 @@ class TimeGenerator(object):
                     home.transportAgent(a, new_home)
                 except Exception as e:
                     print('-- Exception --')
-                    print('moving "%s" from "%s" to "%s"' %(a, h, repr(new_home)))
+                    print('moving "%s" from "%s" to "%s"' %
+                          (a, h, repr(new_home)))
                     print(e)
                     print()
                 self.teardownAgent(a)
@@ -264,6 +285,7 @@ def WanderLust(agent):
     if int(random.random()*100) <= 30:
         return 1
 
+
 def GreenerPastures(agent):
     """ where do they want to go today """
     global _homes
@@ -286,7 +308,7 @@ all_homes = (
 origin = all_homes[1]
 
 for h in all_homes:
-    _homes[h.getId()]=h
+    _homes[h.getId()] = h
 
 
 agents = [
@@ -296,7 +318,7 @@ agents = [
     Agent('thucydides', None, 'greek men', action_find_time),
     Agent('archimedes', None, 'greek men', action_find_neighbors),
     Agent('prometheus', None, 'greek men', action_find_homes),
-    ]
+]
 
 for a in agents:
     origin.addAgent(a)
@@ -312,5 +334,6 @@ def main():
     for h in _homes.values():
         print(h.getId(), h.getAgentIds())
 
+
 if __name__ == '__main__':
     main()
diff --git a/src/zope/security/examples/sandbox_security.py b/src/zope/security/examples/sandbox_security.py
index d0bfe15..5115ca7 100644
--- a/src/zope/security/examples/sandbox_security.py
+++ b/src/zope/security/examples/sandbox_security.py
@@ -17,13 +17,13 @@ This module is responsible of securing the sandbox application and run it in a
 secure mode. There are several steps that are taken to set up the security
 
   1. map permissions to actions
-  
+
   2. map authentication tokens/principals onto permissions
-  
+
   3. implement checker and security policies that affect 1,2
-  
+
   4. bind checkers to classes/instances
-  
+
   5. proxy wrap as necessary
 """
 import sandbox
@@ -32,7 +32,7 @@ from zope.security import checker, management, simplepolicies
 from zope.interface import implementer
 
 
-# Define all permissions that will be available 
+# Define all permissions that will be available
 NotAllowed = 'Not Allowed'
 Public = checker.CheckerPublic
 TransportAgent = 'Transport Agent'
@@ -43,9 +43,10 @@ AccessAgentService = 'Access Agent Service'
 AccessHomeService = 'Access Home Service'
 
 AddAgent = 'Add Agent'
-ALL='All'
+ALL = 'All'
+
 
-NoSetAttr = lambda name: NotAllowed
+def NoSetAttr(name): return NotAllowed
 
 
 class SimulationSecurityDatabase(object):
@@ -55,20 +56,20 @@ class SimulationSecurityDatabase(object):
     permissions.
     """
     origin = {
-        'any' : [ALL]
-        }
+        'any': [ALL]
+    }
 
     jail = {
-        'norse legend' : [TransportAgent, AccessServices, AccessAgentService,
-                          AccessHomeService, TransportAgent, AccessAgents],
-        'any' : [AccessTimeService, AddAgent]
-        }
+        'norse legend': [TransportAgent, AccessServices, AccessAgentService,
+                         AccessHomeService, TransportAgent, AccessAgents],
+        'any': [AccessTimeService, AddAgent]
+    }
 
     valhalla = {
-        'norse legend' : [AddAgent],
-        'any' : [AccessServices, AccessTimeService, AccessAgentService,
-                 AccessHomeService, TransportAgent, AccessAgents]
-        }
+        'norse legend': [AddAgent],
+        'any': [AccessServices, AccessTimeService, AccessAgentService,
+                AccessHomeService, TransportAgent, AccessAgents]
+    }
 
 
 class SimulationSecurityPolicy(simplepolicies.ParanoidSecurityPolicy):
@@ -108,7 +109,6 @@ class AgentParticipation(object):
     A very simple participation that is specific to the simulations.
     """
 
-
     def __init__(self, agent):
         self.principal = agent
         self.interaction = None
@@ -130,27 +130,27 @@ def PermissionMapChecker(permissions_map=None, set_permissions=None):
 #################################
 # sandbox security settings
 sandbox_security = {
-    AccessServices : ['getService', 'addService', 'getServiceIds'],
-    AccessAgents : ['getAgentsIds', 'getAgents'],
-    AddAgent : ['addAgent'],
-    TransportAgent : ['transportAgent'],
-    Public : ['getId','getHome']
-    }
+    AccessServices: ['getService', 'addService', 'getServiceIds'],
+    AccessAgents: ['getAgentsIds', 'getAgents'],
+    AddAgent: ['addAgent'],
+    TransportAgent: ['transportAgent'],
+    Public: ['getId', 'getHome']
+}
 sandbox_checker = PermissionMapChecker(sandbox_security)
 
 #################################
 # service security settings
 
 # time service
-tservice_security = { AccessTimeService:['getTime'] }
+tservice_security = {AccessTimeService: ['getTime']}
 time_service_checker = PermissionMapChecker(tservice_security)
 
 # home service
-hservice_security = { AccessHomeService:['getAvailableHomes'] }
+hservice_security = {AccessHomeService: ['getAvailableHomes']}
 home_service_checker = PermissionMapChecker(hservice_security)
 
 # agent service
-aservice_security = { AccessAgentService:['getLocalAgents'] }
+aservice_security = {AccessAgentService: ['getLocalAgents']}
 agent_service_checker = PermissionMapChecker(aservice_security)
 
 
@@ -164,14 +164,14 @@ def wire_security():
     checker.defineChecker(sandbox.HomeDiscoveryService, home_service_checker)
 
     def addAgent(self, agent):
-        if not self._agents.has_key(agent.getId()) \
-           and sandbox.IAgent.providedBy(agent):
-            self._agents[agent.getId()]=agent
+        if (agent.getId() not in self._agents
+                and sandbox.IAgent.providedBy(agent)):
+            self._agents[agent.getId()] = agent
             agentChecker = checker.selectChecker(self)
             wrapped_home = agentChecker.proxy(self)
             agent.setHome(wrapped_home)
         else:
-            raise sandbox.SandboxError("couldn't add agent %s" %agent)
+            raise sandbox.SandboxError("couldn't add agent %s" % agent)
 
     sandbox.Sandbox.addAgent = addAgent
 
@@ -191,7 +191,7 @@ def wire_security():
         _homes = sandbox._homes
         possible_homes = _homes.keys()
         possible_homes.remove(agent.getHome().getId())
-        new_home =  _homes.get(random.choice(possible_homes))
+        new_home = _homes.get(random.choice(possible_homes))
         return checker.selectChecker(new_home).proxy(new_home)
 
     sandbox.GreenerPastures = GreenerPastures
diff --git a/src/zope/security/interfaces.py b/src/zope/security/interfaces.py
index 74cd385..890e6fc 100644
--- a/src/zope/security/interfaces.py
+++ b/src/zope/security/interfaces.py
@@ -62,6 +62,7 @@ from zope.security.i18n import ZopeMessageFactory as _
 #: .. versionadded:: 4.2.0
 PUBLIC_PERMISSION_NAME = 'zope.Public'
 
+
 class IUnauthorized(IException):
     """
     The action is not authorized.
@@ -69,6 +70,7 @@ class IUnauthorized(IException):
     Implemented in :class:`Unauthorized`.
     """
 
+
 @implementer(IUnauthorized)
 class Unauthorized(Exception):
     """
@@ -77,6 +79,7 @@ class Unauthorized(Exception):
     Default implementation of :class:`IUnauthorized`.
     """
 
+
 class IForbidden(IException):
     """
     A resource cannot be accessed under any circumstances
@@ -84,6 +87,7 @@ class IForbidden(IException):
     Implemented in :class:`Forbidden`.
     """
 
+
 @implementer(IForbidden)
 class Forbidden(Exception):
     """
@@ -92,6 +96,7 @@ class Forbidden(Exception):
     Default implementation if :class:`IForbidden`.
     """
 
+
 class IForbiddenAttribute(IForbidden, IAttributeError):
     """
     An attribute is unavailable because it is forbidden (private).
@@ -99,6 +104,7 @@ class IForbiddenAttribute(IForbidden, IAttributeError):
     Implemented in :class:`ForbiddenAttribute`.
     """
 
+
 @implementer(IForbiddenAttribute)
 class ForbiddenAttribute(Forbidden, AttributeError):
     """
@@ -137,9 +143,9 @@ class ISecurityChecking(Interface):
 
         :param str permission: The permission name.
         :param object: The object being accessed according to the permission.
-        :keyword interaction: An :class:`IInteraction`, providing access to information
-            such as authenticated principals.  If it is None, the current
-            interaction is used.
+        :keyword interaction: An :class:`IInteraction`, providing access to
+            information such as authenticated principals.  If it is None, the
+            current interaction is used.
         """
 
 
@@ -257,7 +263,8 @@ class INameBasedChecker(IChecker):
         """
         Return the permission used to check attribute access on *name*.
 
-        This permission is used by both :meth:`check` and :meth:`check_getattr`.
+        This permission is used by both :meth:`check` and
+        :meth:`check_getattr`.
         """
 
     def setattr_permission_id(name):
@@ -322,6 +329,7 @@ class NoInteraction(Exception):
     """No interaction started
     """
 
+
 class IInteractionManagement(Interface):
     """
     Interaction management API.
@@ -362,6 +370,7 @@ class IInteractionManagement(Interface):
         Does nothing if there is no interaction.
         """
 
+
 class IPrincipal(Interface):
     """
     Principals are security artifacts that execute actions in a
@@ -417,7 +426,9 @@ class IGroupAwarePrincipal(IPrincipal):
     """
 
     groups = Attribute(
-        'An iterable of :class:`IGroup` objects to which the principal directly belongs')
+        'An iterable of :class:`IGroup` objects to which the principal'
+        ' directly belongs')
+
 
 class IGroupClosureAwarePrincipal(IGroupAwarePrincipal):
     """
@@ -428,11 +439,13 @@ class IGroupClosureAwarePrincipal(IGroupAwarePrincipal):
     allGroups = Attribute(
         "An iterable of the full closure of the principal's groups.")
 
+
 class IGroup(IPrincipal):
     """
     Group of principals
     """
 
+
 class IMemberGetterGroup(IGroup):
     """
     A group that can get its members.
@@ -441,6 +454,7 @@ class IMemberGetterGroup(IGroup):
     def getMembers():
         """Return an iterable of the members of the group"""
 
+
 class IMemberAwareGroup(IMemberGetterGroup):
     """
     A group that can both set and get its members.
@@ -452,6 +466,7 @@ class IMemberAwareGroup(IMemberGetterGroup):
         *value*.
         """
 
+
 class IPermission(Interface):
     """A permission object.
 
diff --git a/src/zope/security/management.py b/src/zope/security/management.py
index 1acc3d3..2daf0ce 100644
--- a/src/zope/security/management.py
+++ b/src/zope/security/management.py
@@ -52,10 +52,12 @@ moduleProvides(
 #   ISecurityManagement implementation
 #
 
+
 def getSecurityPolicy():
     """Get the system default security policy."""
     return _defaultPolicy
 
+
 def setSecurityPolicy(aSecurityPolicy):
     """Set the system default security policy, and return the previous
     value.
@@ -78,6 +80,7 @@ def queryInteraction():
     """Return a current interaction, if there is one."""
     return getattr(thread_local, 'interaction', None)
 
+
 def getInteraction():
     """Get the current interaction."""
     try:
@@ -85,14 +88,16 @@ def getInteraction():
     except AttributeError:
         raise NoInteraction
 
+
 class ExistingInteraction(ValueError,
-                          AssertionError, #BBB
-                         ):
+                          AssertionError,  # BBB
+                          ):
     """
     The exception that :func:`newInteraction` will raise if called
     during an existing interaction.
     """
 
+
 def newInteraction(*participations):
     """Start a new interaction."""
     if queryInteraction() is not None:
@@ -100,6 +105,7 @@ def newInteraction(*participations):
                                   " while another interaction is active.")
     thread_local.interaction = getSecurityPolicy()(*participations)
 
+
 def endInteraction():
     """End the current interaction."""
 
@@ -116,6 +122,7 @@ def endInteraction():
     else:
         del thread_local.interaction
 
+
 def restoreInteraction():
     try:
         previous = thread_local.previous_interaction
@@ -127,6 +134,7 @@ def restoreInteraction():
     else:
         thread_local.interaction = previous
 
+
 def checkPermission(permission, object, interaction=None):
     """Return whether security policy allows permission on object.
 
@@ -155,9 +163,10 @@ def _clear():
     global _defaultPolicy
     _defaultPolicy = ParanoidSecurityPolicy
 
+
 try:
     from zope.testing.cleanup import addCleanUp
-except ImportError: # pragma: no cover
+except ImportError:  # pragma: no cover
     pass
 else:
     addCleanUp(_clear)
diff --git a/src/zope/security/metaconfigure.py b/src/zope/security/metaconfigure.py
index a9ac6ed..ee437da 100644
--- a/src/zope/security/metaconfigure.py
+++ b/src/zope/security/metaconfigure.py
@@ -40,16 +40,18 @@ def dottedName(klass):
         return 'None'
     return klass.__module__ + '.' + klass.__name__
 
+
 class ProtectionDeclarationException(Exception):
     """Security-protection-specific exceptions."""
     pass
 
+
 class ClassDirective(object):
 
     def __init__(self, _context, class_):
-        self.__id = dottedName(class_) # this would barf on a module, anyway
+        self.__id = dottedName(class_)  # this would barf on a module, anyway
         self.__class = class_
-        if isinstance(self.__class, ModuleType): #pragma NO COVER
+        if isinstance(self.__class, ModuleType):  # pragma: no cover
             raise ConfigurationError('Content class attribute must be a class')
         self.__context = _context
 
@@ -198,12 +200,12 @@ def protectModule(module, name, permission):
 def _names(attributes, interfaces):
     seen = {}
     for name in attributes:
-        if not name in seen:
+        if name not in seen:
             seen[name] = 1
             yield name
     for interface in interfaces:
         for name in interface:
-            if not name in seen:
+            if name not in seen:
                 seen[name] = 1
                 yield name
 
diff --git a/src/zope/security/metadirectives.py b/src/zope/security/metadirectives.py
index c0830d6..3e85cfd 100644
--- a/src/zope/security/metadirectives.py
+++ b/src/zope/security/metadirectives.py
@@ -26,13 +26,15 @@ import zope.security.zcml
 from zope.security.i18n import ZopeMessageFactory as _
 from zope.security.zcml import Permission
 
+
 class IClassDirective(zope.interface.Interface):
     """Make statements about a class"""
 
     class_ = zope.configuration.fields.GlobalObject(
         title=_("Class"),
         required=True
-        )
+    )
+
 
 class IImplementsSubdirective(zope.interface.Interface):
     """Declare that the class given by the content directive's class
@@ -43,7 +45,8 @@ class IImplementsSubdirective(zope.interface.Interface):
         title=_("One or more interfaces"),
         required=True,
         value_type=zope.configuration.fields.GlobalInterface()
-        )
+    )
+
 
 class IRequireSubdirective(zope.interface.Interface):
     """Indicate that the a specified list of names or the names in a
@@ -56,7 +59,7 @@ class IRequireSubdirective(zope.interface.Interface):
         Specifies the permission by id that will be required to
         access or mutate the attributes and methods specified."""),
         required=False,
-        )
+    )
 
     attributes = zope.configuration.fields.Tokens(
         title=_("Attributes and methods"),
@@ -64,7 +67,7 @@ class IRequireSubdirective(zope.interface.Interface):
                       " that can be accessed."),
         required=False,
         value_type=zope.configuration.fields.PythonIdentifier(),
-        )
+    )
 
     set_attributes = zope.configuration.fields.Tokens(
         title=_("Attributes that can be set"),
@@ -72,7 +75,7 @@ class IRequireSubdirective(zope.interface.Interface):
                       " modified/mutated."),
         required=False,
         value_type=zope.configuration.fields.PythonIdentifier(),
-        )
+    )
 
     interface = zope.configuration.fields.Tokens(
         title=_("Interfaces"),
@@ -80,7 +83,7 @@ class IRequireSubdirective(zope.interface.Interface):
                       " can be accessed."),
         required=False,
         value_type=zope.configuration.fields.GlobalInterface(),
-        )
+    )
 
     set_schema = zope.configuration.fields.Tokens(
         title=_("The attributes specified by the schema can be set"),
@@ -88,7 +91,7 @@ class IRequireSubdirective(zope.interface.Interface):
                       " modified/mutated."),
         required=False,
         value_type=zope.configuration.fields.GlobalInterface(),
-        )
+    )
 
     like_class = zope.configuration.fields.GlobalObject(
         title=_("Configure like this class"),
@@ -97,7 +100,8 @@ class IRequireSubdirective(zope.interface.Interface):
         same way the specified class' security is. If this argument is
         specified, no other argument can be used."""),
         required=False,
-        )
+    )
+
 
 class IAllowSubdirective(zope.interface.Interface):
     """
@@ -110,13 +114,14 @@ class IAllowSubdirective(zope.interface.Interface):
         title=_("Attributes"),
         required=False,
         value_type=zope.configuration.fields.PythonIdentifier(),
-        )
+    )
 
     interface = zope.configuration.fields.Tokens(
         title=_("Interface"),
         required=False,
         value_type=zope.configuration.fields.GlobalInterface(),
-        )
+    )
+
 
 class IFactorySubdirective(zope.interface.Interface):
     """Specify the factory used to create this content object"""
@@ -128,21 +133,22 @@ class IFactorySubdirective(zope.interface.Interface):
         identification scheme.  If not given, defaults to the literal
         string given as the content directive's 'class' attribute."""),
         required=False,
-        )
+    )
 
     title = zope.configuration.fields.MessageID(
         title=_("Title"),
         description=_("Text suitable for use in the 'add content' menu"
                       " of a management interface"),
         required=False,
-        )
+    )
 
     description = zope.configuration.fields.MessageID(
         title=_("Description"),
         description=_("Longer narrative description of what this"
                       " factory does"),
         required=False,
-        )
+    )
+
 
 class IModule(Interface):
     """Group security declarations about a module"""
diff --git a/src/zope/security/permission.py b/src/zope/security/permission.py
index 88ba978..da0dd40 100644
--- a/src/zope/security/permission.py
+++ b/src/zope/security/permission.py
@@ -29,6 +29,7 @@ from zope.security.checker import CheckerPublic
 from zope.security.interfaces import IPermission
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 @implementer(IPermission)
 class Permission(object):
     """
@@ -40,6 +41,7 @@ class Permission(object):
         self.title = title
         self.description = description
 
+
 def checkPermission(context, permission_id):
     """
     Check whether a given permission object exists in the provided
@@ -50,6 +52,7 @@ def checkPermission(context, permission_id):
     if not queryUtility(IPermission, permission_id, context=context):
         raise ValueError("Undefined permission ID", permission_id)
 
+
 def allPermissions(context=None):
     """
     Get the IDs of all defined permission object utilities.
@@ -58,6 +61,7 @@ def allPermissions(context=None):
         if name != zope_Public:
             yield name
 
+
 def PermissionsVocabulary(context=None):
     """
     A vocabulary of permission IDs.
@@ -69,8 +73,10 @@ def PermissionsVocabulary(context=None):
         terms.append(SimpleTerm(permission, name))
     return SimpleVocabulary(terms)
 
+
 directlyProvides(PermissionsVocabulary, IVocabularyFactory)
 
+
 def PermissionIdsVocabulary(context=None):
     """
     A vocabulary of permission IDs.
@@ -100,4 +106,5 @@ def PermissionIdsVocabulary(context=None):
         terms.insert(0, SimpleTerm(CheckerPublic, zope_Public, u'Public'))
     return SimpleVocabulary(terms)
 
+
 directlyProvides(PermissionIdsVocabulary, IVocabularyFactory)
diff --git a/src/zope/security/protectclass.py b/src/zope/security/protectclass.py
index 1b93994..ee897cd 100644
--- a/src/zope/security/protectclass.py
+++ b/src/zope/security/protectclass.py
@@ -37,6 +37,7 @@ def protectName(class_, name, permission):
     protections = checker.get_permissions
     protections[name] = permission
 
+
 def protectSetAttribute(class_, name, permission):
     """Set a permission on a particular name."""
     checker = getCheckerForInstancesOf(class_)
@@ -58,6 +59,7 @@ def protectSetAttribute(class_, name, permission):
     protections = checker.set_permissions
     protections[name] = permission
 
+
 def protectLikeUnto(class_, like_unto):
     """Use the protections from like_unto for the given class."""
 
diff --git a/src/zope/security/proxy.py b/src/zope/security/proxy.py
index b64fd0a..1f4281c 100644
--- a/src/zope/security/proxy.py
+++ b/src/zope/security/proxy.py
@@ -22,10 +22,11 @@ import sys
 from zope.proxy import PyProxyBase
 from zope.security._compat import PURE_PYTHON
 from zope.security._compat import _BUILTINS
-from zope.security.interfaces import ForbiddenAttribute
+
 
 def _check_name(meth, wrap_result=True):
     name = meth.__name__
+
     def _wrapper(self, *args, **kw):
         wrapped = super(PyProxyBase, self).__getattribute__('_wrapped')
         checker = super(PyProxyBase, self).__getattribute__('_checker')
@@ -36,8 +37,10 @@ def _check_name(meth, wrap_result=True):
         return checker.proxy(res)
     return functools.update_wrapper(_wrapper, meth)
 
+
 def _check_name_inplace(meth):
     name = meth.__name__
+
     def _wrapper(self, *args, **kw):
         wrapped = super(PyProxyBase, self).__getattribute__('_wrapped')
         checker = super(PyProxyBase, self).__getattribute__('_checker')
@@ -47,19 +50,20 @@ def _check_name_inplace(meth):
             # The proxy object cannot change; we are modifying in place.
             self._wrapped = w_meth(*args, **kw)
             return self
-        x_name = '__%s__' %  name[3:-2]
+        x_name = '__%s__' % name[3:-2]
         return ProxyPy(getattr(wrapped, x_name)(*args, **kw), checker)
     return functools.update_wrapper(_wrapper, meth)
 
+
 def _fmt_address(obj):
     # Try to replicate PyString_FromString("%p", obj), which actually uses
     # the platform sprintf(buf, "%p", obj), which we cannot access from Python
     # directly (and ctypes seems like overkill).
     if sys.platform != 'win32':
         return '0x%0x' % id(obj)
-    if sys.maxsize < 2**32: # pragma: no cover
+    if sys.maxsize < 2**32:  # pragma: no cover
         return '0x%08X' % id(obj)
-    return '0x%016X' % id(obj) # pragma: no cover
+    return '0x%016X' % id(obj)  # pragma: no cover
 
 
 class ProxyPy(PyProxyBase):
@@ -114,15 +118,16 @@ class ProxyPy(PyProxyBase):
             # of this object just like the Python language spec states, letting
             # them have precedence over things found in the instance. This
             # normally makes us a better proxy implementation. However, the
-            # C version of this code in _proxy doesn't take that same care and instead
-            # uses the generic object attribute access methods directly on
-            # the wrapped object. This is a behaviour difference; so far, it's
-            # only been noticed for the __module__ attribute, which checker:Global
-            # wants to override but couldn't because this object's type's __module__ would
-            # get in the way. That broke pickling, and checker:Global can't return
-            # anything more sophisticated than a str (a tuple) because it gets proxied
-            # and breaks pickling again. Our solution is to match the C version for this
-            # one attribute.
+            # C version of this code in _proxy doesn't take that same care and
+            # instead uses the generic object attribute access methods directly
+            # on the wrapped object. This is a behaviour difference; so far,
+            # it's only been noticed for the __module__ attribute, which
+            # checker:Global wants to override but couldn't because this
+            # object's type's __module__ would get in the way. That broke
+            # pickling, and checker:Global can't return anything more
+            # sophisticated than a str (a tuple) because it gets proxied and
+            # breaks pickling again. Our solution is to match the C version for
+            # this one attribute.
             val = getattr(wrapped, name)
         else:
             val = super(ProxyPy, self).__getattribute__(name)
@@ -146,8 +151,8 @@ class ProxyPy(PyProxyBase):
         # explicitly do the same. The consequence is that we lose a
         # good stack trace if the object implemented its own methods
         # but we're consistent. We would provide a better error
-        # message or even subclass of AttributeError, but that's liable to break
-        # (doc)tests.
+        # message or even subclass of AttributeError, but that's liable to
+        # break (doc)tests.
         wrapped = super(ProxyPy, self).__getattribute__('_wrapped')
         checker = super(ProxyPy, self).__getattribute__('_checker')
         checker.check_getattr(wrapped, name)
@@ -170,7 +175,7 @@ class ProxyPy(PyProxyBase):
         delattr(wrapped, name)
 
     @_check_name
-    def __getslice__(self, start, end):
+    def __getslice__(self, start, end):  # pragma: no cover PY2
         wrapped = object.__getattribute__(self, '_wrapped')
         try:
             getslice = wrapped.__getslice__
@@ -179,7 +184,7 @@ class ProxyPy(PyProxyBase):
         return getslice(start, end)
 
     @_check_name
-    def __setslice__(self, start, end, value):
+    def __setslice__(self, start, end, value):  # pragma: no cover PY2
         wrapped = object.__getattribute__(self, '_wrapped')
         try:
             setslice = wrapped.__setslice__
@@ -187,10 +192,10 @@ class ProxyPy(PyProxyBase):
             return wrapped.__setitem__(slice(start, end), value)
         return setslice(start, end, value)
 
-    def __cmp__(self, other):
+    def __cmp__(self, other):  # pragma: no cover PY2
         # no check
         wrapped = super(ProxyPy, self).__getattribute__('_wrapped')
-        return cmp(wrapped, other)
+        return cmp(wrapped, other)  # noqa: F821 undefined name 'cmp'
 
     def __lt__(self, other):
         # no check
@@ -243,7 +248,7 @@ class ProxyPy(PyProxyBase):
         else:
             return hint()
 
-    def __coerce__(self, other):
+    def __coerce__(self, other):  # pragma: no cover PY2
         # For some reason _check_name does not work for coerce()
         wrapped = super(ProxyPy, self).__getattribute__('_wrapped')
         checker = super(ProxyPy, self).__getattribute__('_checker')
@@ -258,10 +263,10 @@ class ProxyPy(PyProxyBase):
         # the wrong type of object.
         except TypeError:
             raise
-        except:
+        except:  # noqa: E722 do not use bare 'except'
             # The C implementation catches all exceptions.
             wrapped = super(ProxyPy, self).__getattribute__('_wrapped')
-            return '<security proxied %s.%s instance at %s>' %(
+            return '<security proxied %s.%s instance at %s>' % (
                 wrapped.__class__.__module__, wrapped.__class__.__name__,
                 _fmt_address(wrapped))
 
@@ -273,28 +278,29 @@ class ProxyPy(PyProxyBase):
         # the wrong type of object.
         except TypeError:
             raise
-        except:
+        except:  # noqa: E722 do not use bare 'except'
             wrapped = super(ProxyPy, self).__getattribute__('_wrapped')
-            return '<security proxied %s.%s instance at %s>' %(
+            return '<security proxied %s.%s instance at %s>' % (
                 wrapped.__class__.__module__, wrapped.__class__.__name__,
                 _fmt_address(wrapped))
 
+
 for name in ['__call__',
-             #'__repr__',
-             #'__str__',
-             #'__unicode__', # Unchecked in C proxy
+             # '__repr__',
+             # '__str__',
+             # '__unicode__', # Unchecked in C proxy
              '__reduce__',
              '__reduce_ex__',
-             #'__lt__',      # Unchecked in C proxy (rich coparison)
-             #'__le__',      # Unchecked in C proxy (rich coparison)
-             #'__eq__',      # Unchecked in C proxy (rich coparison)
-             #'__ne__',      # Unchecked in C proxy (rich coparison)
-             #'__ge__',      # Unchecked in C proxy (rich coparison)
-             #'__gt__',      # Unchecked in C proxy (rich coparison)
-             #'__nonzero__', # Unchecked in C proxy (rich coparison)
-             #'__bool__',    # Unchecked in C proxy (rich coparison)
-             #'__hash__',    # Unchecked in C proxy (rich coparison)
-             #'__cmp__',     # Unchecked in C proxy
+             # '__lt__',      # Unchecked in C proxy (rich coparison)
+             # '__le__',      # Unchecked in C proxy (rich coparison)
+             # '__eq__',      # Unchecked in C proxy (rich coparison)
+             # '__ne__',      # Unchecked in C proxy (rich coparison)
+             # '__ge__',      # Unchecked in C proxy (rich coparison)
+             # '__gt__',      # Unchecked in C proxy (rich coparison)
+             # '__nonzero__', # Unchecked in C proxy (rich coparison)
+             # '__bool__',    # Unchecked in C proxy (rich coparison)
+             # '__hash__',    # Unchecked in C proxy (rich coparison)
+             # '__cmp__',     # Unchecked in C proxy
              '__getitem__',
              '__setitem__',
              '__delitem__',
@@ -341,7 +347,7 @@ for name in ['__call__',
              '__rand__',
              '__rxor__',
              '__ror__',
-            ]:
+             ]:
     meth = getattr(PyProxyBase, name)
     setattr(ProxyPy, name, _check_name(meth))
 
@@ -364,16 +370,18 @@ for name in ['__iadd__',
              '__ixor__',
              '__ior__',
              '__ipow__',
-            ]:
+             ]:
     meth = getattr(PyProxyBase, name)
     setattr(ProxyPy, name, _check_name_inplace(meth))
 
+
 def getCheckerPy(proxy):
     return super(ProxyPy, proxy).__getattribute__('_checker')
 
 
 _builtin_isinstance = sys.modules[_BUILTINS].isinstance
 
+
 def getObjectPy(proxy):
     if not _builtin_isinstance(proxy, ProxyPy):
         return proxy
@@ -381,10 +389,10 @@ def getObjectPy(proxy):
 
 
 _c_available = not PURE_PYTHON
-if _c_available:
+if _c_available:  # pragma: no cover
     try:
         from zope.security._proxy import _Proxy
-    except (ImportError, AttributeError): # pragma: no cover PyPy / PURE_PYTHON
+    except (ImportError, AttributeError):
         _c_available = False
 
 
@@ -392,13 +400,14 @@ getChecker = getCheckerPy
 getObject = getObjectPy
 Proxy = ProxyPy
 
-if _c_available:
+if _c_available:  # pragma: no cover
     from zope.security._proxy import getChecker
     from zope.security._proxy import getObject
     Proxy = _Proxy
 
 removeSecurityProxy = getObject
 
+
 def getTestProxyItems(proxy):
     """Return a sorted sequence of checker names and permissions for testing
     """
diff --git a/src/zope/security/testing.py b/src/zope/security/testing.py
index bd4b889..792813f 100644
--- a/src/zope/security/testing.py
+++ b/src/zope/security/testing.py
@@ -37,6 +37,7 @@ rules = [
 ]
 output_checker = renormalizing.RENormalizing(rules)
 
+
 @interface.implementer(interfaces.IPrincipal)
 class Principal(object):
     """
@@ -55,8 +56,10 @@ class Principal(object):
 @interface.implementer(interfaces.IParticipation)
 class Participation(object):
     """
-    A trivial implementation of :class:`zope.security.interfaces.IParticipation`.
+    A trivial implementation of
+    :class:`zope.security.interfaces.IParticipation`.
     """
+
     def __init__(self, principal):
         self.principal = principal
         self.interaction = None
@@ -82,6 +85,7 @@ def addCheckerPublic():
 
     return perm
 
+
 def create_interaction(principal_id, **kw):
     """
     Create a new interaction for the given principal ID, make it the
diff --git a/src/zope/security/tests/__init__.py b/src/zope/security/tests/__init__.py
index cab4c90..e8db221 100644
--- a/src/zope/security/tests/__init__.py
+++ b/src/zope/security/tests/__init__.py
@@ -9,7 +9,8 @@ class QuietWatchingChecker(object):
     def setUp(self):
         from zope.security import checker
         self.__old_file = checker.CheckerLoggingMixin._file
-        checker.CheckerLoggingMixin._file = io.StringIO() if bytes is not str else io.BytesIO()
+        checker.CheckerLoggingMixin._file = (
+            io.StringIO() if bytes is not str else io.BytesIO())
 
     def tearDown(self):
         from zope.security import checker
diff --git a/src/zope/security/tests/exampleclass.py b/src/zope/security/tests/exampleclass.py
index 1d73b4b..385dda0 100644
--- a/src/zope/security/tests/exampleclass.py
+++ b/src/zope/security/tests/exampleclass.py
@@ -15,14 +15,18 @@
 """
 from zope.interface import Interface
 
+
 class ExampleClass(object):
     pass
 
+
 class IExample(Interface):
     pass
 
+
 class IExample2(Interface):
     pass
 
+
 class IExampleContainer(Interface):
     pass
diff --git a/src/zope/security/tests/module.py b/src/zope/security/tests/module.py
index 5b26ff5..a4f9e73 100644
--- a/src/zope/security/tests/module.py
+++ b/src/zope/security/tests/module.py
@@ -21,23 +21,28 @@ modules, themselves.
 from zope.interface import Interface
 from zope.schema import Text
 
-class I(Interface):
+
+class I(Interface):  # noqa: E742 ambiguous class definition 'I'
     def m1():
-        "m1"
+        """m1"""
+
     def m2():
-        "m2"
+        """m2"""
+
 
 class I2(I):
     def m4():
-        "m4"
+        """m4"""
+
 
 class I3(Interface):
     def m3():
-        "m3"
+        """m3"""
+
 
 class I4(Interface):
     def m2():
-        "m2"
+        """m2"""
 
 
 class S(Interface):
@@ -45,6 +50,7 @@ class S(Interface):
     bar = Text()
     baro = Text(readonly=True)
 
+
 class S2(Interface):
     foo2 = Text()
     bar2 = Text()
diff --git a/src/zope/security/tests/test_adapter.py b/src/zope/security/tests/test_adapter.py
index a3dd541..2d68b0e 100644
--- a/src/zope/security/tests/test_adapter.py
+++ b/src/zope/security/tests/test_adapter.py
@@ -21,6 +21,7 @@ from zope.proxy import getProxiedObject
 
 # pylint:disable=attribute-defined-outside-init,protected-access
 
+
 class Test_assertLocation(unittest.TestCase):
 
     def _callFUT(self, adapter, parent):
@@ -49,6 +50,7 @@ class Test_assertLocation(unittest.TestCase):
 
     def test_w_ILocation_w_parent(self):
         parent = object()
+
         @implementer(ILocation)
         class _Adapter(object):
             __parent__ = parent
@@ -73,6 +75,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
             __name__ = 'testing'
             __module__ = 'zope.security.tests.test_adapter'
             _called_with = ()
+
             def __call__(self, *args):
                 self._called_with = args
                 return self
@@ -88,6 +91,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
     def test__call__w_non_ILocation_non_spacesuit(self):
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -97,11 +101,12 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in returned.__dict__.items()
                  if k != '_called_with'}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_non_spacesuit_multiple_args(self):
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -112,13 +117,14 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in returned.__dict__.items()
                  if k != '_called_with'}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_existing_parent_non_spacesuit(self):
         factory = self._makeFactory()
         parent = factory.__parent__ = object()
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -131,6 +137,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = None
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -143,6 +150,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -157,13 +165,14 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_w_spacesuit_multiple_args(self):
         from zope.security.proxy import ProxyFactory
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -179,15 +188,17 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_multiple_args_extra_spacesuit(self):
         from zope.security.proxy import ProxyFactory
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
+
         class _Extra(object):
             pass
         adapter = _NotAdapter()
@@ -203,7 +214,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_spacesuit(self):
         from zope.security.proxy import getObject
@@ -213,6 +224,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = factory.__name__ = None
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _Adapter(object):
             pass
         adapter = _Adapter()
@@ -229,7 +241,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
                  if k not in ('_called_with', '__parent__')}
         self.assertEqual(factory._called_with, (adapter,))
         self.assertIs(factory.__parent__, adapter)
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_spacesuit_w_existing_parent(self):
         from zope.security.proxy import getObject
@@ -240,6 +252,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = parent = object()
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _Adapter(object):
             pass
         adapter = _Adapter()
@@ -255,7 +268,7 @@ class LocatingTrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with', '__parent__')}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
 
 class TrustedAdapterFactoryTests(unittest.TestCase):
@@ -271,6 +284,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         class _Factory(object):
             __name__ = 'testing'
             __module__ = 'zope.security.tests.test_adapter'
+
             def __call__(self, *args):
                 self._called_with = args
                 return self
@@ -281,6 +295,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -294,13 +309,14 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_w_spacesuit_multiple_args(self):
         from zope.security.proxy import ProxyFactory
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -315,15 +331,17 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_multiple_args_extra_spacesuit(self):
         from zope.security.proxy import ProxyFactory
         from zope.security.proxy import removeSecurityProxy
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
+
         class _Extra(object):
             pass
         adapter = _NotAdapter()
@@ -338,7 +356,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with',)}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_spacesuit(self):
         from zope.security.proxy import ProxyFactory
@@ -347,6 +365,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = factory.__name__ = None
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _Adapter(object):
             pass
         adapter = _Adapter()
@@ -361,7 +380,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with', '__parent__')}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_spacesuit_w_existing_parent(self):
         from zope.security.proxy import ProxyFactory
@@ -371,6 +390,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = parent = object()
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _Adapter(object):
             pass
         adapter = _Adapter()
@@ -385,7 +405,7 @@ class TrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in unwrapped.__dict__.items()
                  if k not in ('_called_with', '__parent__')}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
 
 class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
@@ -402,6 +422,7 @@ class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
             __name__ = 'testing'
             __module__ = 'zope.security.tests.test_adapter'
             _called_with = ()
+
             def __call__(self, *args):
                 self._called_with = args
                 return self
@@ -417,6 +438,7 @@ class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
     def test__call__w_non_ILocation(self):
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -428,11 +450,12 @@ class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in returned.__dict__.items()
                  if k != '_called_with'}
         self.assertEqual(factory._called_with, (adapter,))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_non_ILocation_multiple_args(self):
         factory = self._makeFactory()
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -445,13 +468,14 @@ class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
         after = {k: v for k, v in returned.__dict__.items()
                  if k != '_called_with'}
         self.assertEqual(factory._called_with, (adapter, extra))
-        self.assertEqual(after, before) # no added attrs
+        self.assertEqual(after, before)  # no added attrs
 
     def test__call__w_ILocation_w_existing_parent(self):
         factory = self._makeFactory()
         parent = factory.__parent__ = object()
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
@@ -464,6 +488,7 @@ class LocatingUntrustedAdapterFactoryTests(unittest.TestCase):
         factory.__parent__ = None
         directlyProvides(factory, ILocation)
         ltaf = self._makeOne(factory)
+
         class _NotAdapter(object):
             pass
         adapter = _NotAdapter()
diff --git a/src/zope/security/tests/test_checker.py b/src/zope/security/tests/test_checker.py
index 3473886..a8b3990 100644
--- a/src/zope/security/tests/test_checker.py
+++ b/src/zope/security/tests/test_checker.py
@@ -33,6 +33,7 @@ class Test_ProxyFactory(unittest.TestCase):
     def test_w_already_proxied_no_checker(self):
         from zope.security.proxy import Proxy, getChecker
         obj = object()
+
         def _check(*x):
             raise AssertionError("Never called")
         proxy = Proxy(obj, _check)
@@ -43,6 +44,7 @@ class Test_ProxyFactory(unittest.TestCase):
     def test_w_already_proxied_same_checker(self):
         from zope.security.proxy import Proxy, getChecker
         obj = object()
+
         def _check(*x):
             raise AssertionError("Never called")
         proxy = Proxy(obj, _check)
@@ -53,9 +55,11 @@ class Test_ProxyFactory(unittest.TestCase):
     def test_w_already_proxied_different_checker(self):
         from zope.security.proxy import Proxy
         obj = object()
+
         def _check(*x):
             raise AssertionError("Never called")
         proxy = Proxy(obj, _check)
+
         def _sneaky(*x):
             raise AssertionError("Never called")
         self.assertRaises(TypeError, self._callFUT, proxy, _sneaky)
@@ -63,6 +67,7 @@ class Test_ProxyFactory(unittest.TestCase):
     def test_w_explicit_checker(self):
         from zope.security.proxy import getChecker
         obj = object()
+
         def _check(*x):
             raise AssertionError("Never called")
         returned = self._callFUT(obj, _check)
@@ -76,7 +81,8 @@ class Test_ProxyFactory(unittest.TestCase):
 
     def test_no_checker_w_dunder(self):
         from zope.security.proxy import getChecker, getObject
-        _check = object() # don't use a func, due to bound method
+        _check = object()  # don't use a func, due to bound method
+
         class _WithChecker(object):
             __Security_checker__ = _check
         obj = _WithChecker()
@@ -90,10 +96,12 @@ class Test_ProxyFactory(unittest.TestCase):
         from zope.security.checker import _checkers
         from zope.security.checker import _clear
         from zope.security.proxy import getChecker, getObject
+
         class _Obj(object):
             pass
         obj = _Obj()
         _checker = Checker({})
+
         def _check(*args):
             return _checker
         _checkers[_Obj] = _check
@@ -117,6 +125,7 @@ class Test_canWrite(unittest.TestCase):
             def check_getattr(self, obj, name):
                 if ch_get is not None:
                     raise ch_get()
+
             def check_setattr(self, obj, name):
                 if ch_set is not None:
                     raise ch_set()
@@ -196,6 +205,7 @@ class Test_canAccess(unittest.TestCase):
 
 _marker = object()
 
+
 class CheckerTestsBase(QuietWatchingChecker):
     # pylint:disable=no-member
 
@@ -267,6 +277,7 @@ class CheckerTestsBase(QuietWatchingChecker):
 
     def test_check_setattr_w_interaction_allows(self):
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return True
@@ -281,6 +292,7 @@ class CheckerTestsBase(QuietWatchingChecker):
     def test_check_setattr_w_interaction_denies(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
@@ -313,6 +325,7 @@ class CheckerTestsBase(QuietWatchingChecker):
 
     def test_check_non_public_w_interaction_allows(self):
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return True
@@ -327,6 +340,7 @@ class CheckerTestsBase(QuietWatchingChecker):
     def test_check_non_public_w_interaction_denies(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
@@ -342,6 +356,7 @@ class CheckerTestsBase(QuietWatchingChecker):
     def test_proxy_already_proxied(self):
         from zope.security.proxy import Proxy, getChecker
         obj = object()
+
         def _check(*x):
             raise AssertionError("Never called")
         proxy = Proxy(obj, _check)
@@ -358,7 +373,8 @@ class CheckerTestsBase(QuietWatchingChecker):
 
     def test_proxy_no_checker_w_dunder(self):
         from zope.security.proxy import getChecker, getObject
-        _check = object() # don't use a func, due to bound method
+        _check = object()  # don't use a func, due to bound method
+
         class _WithChecker(object):
             __Security_checker__ = _check
         obj = _WithChecker()
@@ -373,10 +389,12 @@ class CheckerTestsBase(QuietWatchingChecker):
         from zope.security.checker import _checkers
         from zope.security.checker import _clear
         from zope.security.proxy import getChecker, getObject
+
         class _Obj(object):
             pass
         obj = _Obj()
         _checker = Checker({})
+
         def _check(*args):
             return _checker
         _checkers[_Obj] = _check
@@ -420,8 +438,8 @@ class CheckerTestsBase(QuietWatchingChecker):
         self.assertEqual(proxy // Decimal('1'), Decimal('1'))
         self.assertEqual(float(proxy), 1.1)
         self.assertEqual(int(proxy), 1)
-        if PY2:
-            self.assertEqual(long(proxy), 1)
+        if PY2:  # pragma: no cover PY2
+            self.assertEqual(long(proxy), 1)  # noqa: F821 undefined name
         self.assertEqual(proxy ** 2, Decimal('1.21'))
         self.assertEqual(1 ** proxy, Decimal('1'))
         self.assertEqual(proxy.adjusted(), 0)
@@ -451,7 +469,6 @@ class CheckerTestsBase(QuietWatchingChecker):
         self.assertEqual([1], list(proxy))
         self.assertEqual([2], list(proxy.values()))
 
-
     def test_iteration_of_btree_items_keys_values(self):
         # iteration of BTree.items() is allowed by default.
         import BTrees
@@ -486,10 +503,10 @@ class CheckerTestsBase(QuietWatchingChecker):
             pass
 
         @implementer(I1)
-        class O(object):
+        class Obj(object):
             pass
 
-        o = O()
+        o = Obj()
 
         checker = Checker({})
 
@@ -497,9 +514,9 @@ class CheckerTestsBase(QuietWatchingChecker):
 
         # Since the object itself doesn't have any interfaces,
         # the providedBy will return the implementedBy of the class
-        l = list(providedBy(proxy))
+        provided_by = list(providedBy(proxy))
 
-        self.assertEqual(l, [I1])
+        self.assertEqual(provided_by, [I1])
 
     def test_iteration_of_interface_providesBy(self):
         # Iteration of zope.interface.Provides is allowed by default
@@ -519,10 +536,10 @@ class CheckerTestsBase(QuietWatchingChecker):
             pass
 
         @implementer(I1)
-        class O(object):
+        class Obj(object):
             pass
 
-        o = O()
+        o = Obj()
         alsoProvides(o, I2)
 
         checker = Checker({})
@@ -531,9 +548,9 @@ class CheckerTestsBase(QuietWatchingChecker):
 
         # Since the object has its own interfaces, provided
         # by will return a zope.interface.Provides object
-        l = list(providedBy(proxy))
+        provided_by = list(providedBy(proxy))
 
-        self.assertEqual(l, [I2, I1])
+        self.assertEqual(provided_by, [I2, I1])
 
     def test_iteration_with_length_hint(self):
         # PEP 424 implemented officially in Python 3.4 and
@@ -577,19 +594,16 @@ class CheckerTestsBase(QuietWatchingChecker):
         # The hint is called when we proxy the root object
         i = Iter()
         proxy = Proxy(i, _iteratorChecker)
-        l = list(proxy)
-        self.assertEqual(l, [0, 1, 2])
+        self.assertEqual(list(proxy), [0, 1, 2])
         self.assertTrue(i.hint_called, "__length_hint__ should be called")
 
         # The hint is called when we proxy its iterator
         i = Iter()
         it = iter(i)
         proxy = Proxy(it, _iteratorChecker)
-        l = list(proxy)
-        self.assertEqual(l, [0, 1, 2])
+        self.assertEqual(list(proxy), [0, 1, 2])
         self.assertTrue(i.hint_called, "__length_hint__ should be called")
 
-
     def test_iteration_of_itertools_groupby(self):
         # itertools.groupby is a custom iterator type.
         # The groups it returns are also custom.
@@ -630,6 +644,7 @@ class TestChecker(CheckerTestsBase, unittest.TestCase):
     def _getTargetClass(self):
         return sec_checker.Checker
 
+
 @unittest.skipIf(sec_checker.Checker is sec_checker.WatchingChecker,
                  "WatchingChecker is the default")
 class TestWatchingChecker(TestChecker):
@@ -637,6 +652,7 @@ class TestWatchingChecker(TestChecker):
     def _getTargetClass(self):
         return sec_checker.WatchingChecker
 
+
 class TestTracebackSupplement(unittest.TestCase):
 
     def _getTargetClass(self):
@@ -654,12 +670,12 @@ class TestTracebackSupplement(unittest.TestCase):
                          ((), 'tuple'),
                          ([], 'list'),
                          ({}, 'dict'),
-                        ]:
+                         ]:
             tbs = self._makeOne(val)
             self.assertEqual(tbs.getInfo().splitlines(),
                              ['   - class: %s.%s' % (_BUILTINS, typ),
                               '   - type: %s.%s' % (_BUILTINS, typ),
-                             ])
+                              ])
 
     def test_getInfo_newstyle_instance(self):
         class C(object):
@@ -668,7 +684,7 @@ class TestTracebackSupplement(unittest.TestCase):
         self.assertEqual(tbs.getInfo().splitlines(),
                          ['   - class: %s.C' % self.__class__.__module__,
                           '   - type: %s.C' % self.__class__.__module__,
-                         ])
+                          ])
 
     def test_getInfo_classic_instance(self):
         class C:
@@ -678,7 +694,9 @@ class TestTracebackSupplement(unittest.TestCase):
         lines = tbs.getInfo().splitlines()
         self.assertEqual(lines[0],
                          '   - class: %s.C' % self.__class__.__module__)
-        kind = '__builtin__.instance' if PY2 else '%s.C' % self.__class__.__module__
+        kind = ('__builtin__.instance'
+                if PY2
+                else '%s.C' % self.__class__.__module__)
         self.assertEqual(lines[1],
                          '   - type: ' + kind)
 
@@ -763,6 +781,7 @@ class Test_InterfaceChecker(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.checker import CheckerPublic
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         checker = self._callFUT(IFoo)
@@ -772,6 +791,7 @@ class Test_InterfaceChecker(unittest.TestCase):
     def test_simple_iface_w_explicit_permission(self):
         from zope.interface import Attribute
         from zope.interface import Interface
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         other_perm = object()
@@ -782,6 +802,7 @@ class Test_InterfaceChecker(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.checker import CheckerPublic
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         other_perm = object()
@@ -794,8 +815,10 @@ class Test_InterfaceChecker(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.checker import CheckerPublic
+
         class IFoo(Interface):
             bar = Attribute('Bar')
+
         class IBar(IFoo):
             baz = Attribute('Baz')
         checker = self._callFUT(IBar)
@@ -807,6 +830,7 @@ class Test_InterfaceChecker(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.checker import DuplicationError
+
         class IFoo(Interface):
             bar = Attribute('Bar')
             bam = Attribute('Bam')
@@ -839,6 +863,7 @@ class Test_MultiChecker(unittest.TestCase):
     def test_w_spec_as_iface(self):
         from zope.interface import Attribute
         from zope.interface import Interface
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         other_perm = object()
@@ -850,6 +875,7 @@ class Test_MultiChecker(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.checker import CheckerPublic
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         other_perm = object()
@@ -865,6 +891,7 @@ class Test_MultiChecker(unittest.TestCase):
         from zope.interface import Interface
         from zope.security.checker import CheckerPublic
         from zope.security.checker import DuplicationError
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         other_perm = object()
@@ -877,7 +904,7 @@ class Test_MultiChecker(unittest.TestCase):
         other_perm = object()
         spec = {'foo': CheckerPublic,
                 'bar': other_perm,
-               }
+                }
         checker = self._callFUT([spec])
         self.assertIs(checker.permission_id('foo'), CheckerPublic)
         self.assertIs(checker.permission_id('bar'), other_perm)
@@ -895,7 +922,6 @@ class Test_MultiChecker(unittest.TestCase):
                           [(('foo', 'bar'), CheckerPublic), spec])
 
 
-
 class _SelectCheckerBase(object):
     # pylint:disable=no-member
 
@@ -927,12 +953,13 @@ class _SelectCheckerBase(object):
                     datetime.date.today(),
                     datetime.datetime.now().time(),
                     datetime.tzinfo(),
-                   ]:
+                    ]:
             self.assertIsNone(self._callFUT(obj))
 
     def test_w_checker_inst(self):
         from zope.security.checker import Checker
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = _checkers[Foo] = Checker({})
@@ -941,9 +968,11 @@ class _SelectCheckerBase(object):
     def test_w_factory_returning_checker(self):
         from zope.security.checker import Checker
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = Checker({})
+
         def _factory(obj):
             return checker
         _checkers[Foo] = _factory
@@ -952,8 +981,10 @@ class _SelectCheckerBase(object):
     def test_w_factory_returning_NoProxy(self):
         from zope.security.checker import NoProxy
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
+
         def _factory(obj):
             return NoProxy
         _checkers[Foo] = _factory
@@ -961,8 +992,10 @@ class _SelectCheckerBase(object):
 
     def test_w_factory_returning_None(self):
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
+
         def _factory(obj):
             pass
         _checkers[Foo] = _factory
@@ -971,11 +1004,14 @@ class _SelectCheckerBase(object):
     def test_w_factory_factory(self):
         from zope.security.checker import Checker
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = Checker({})
+
         def _factory(obj):
             return checker
+
         def _factory_factory(obj):
             return _factory
         _checkers[Foo] = _factory_factory
@@ -983,16 +1019,17 @@ class _SelectCheckerBase(object):
 
     def test_itertools_checkers(self):
         from zope.security.checker import _iteratorChecker
-        import sys
         import itertools
-        pred = lambda x: x
+
+        def pred(x):
+            return x
         iterable = (1, 2, 3)
         pred_iterable = (pred, iterable)
         missing_in_py3 = {'ifilter', 'ifilterfalse', 'imap',
                           'izip', 'izip_longest'}
         missing_in_py2 = {'zip_longest', 'accumulate', 'compress',
                           'combinations', 'combinations_with_replacement'}
-        missing = missing_in_py3 if sys.version_info[0] >= 3 else missing_in_py2
+        missing = missing_in_py3 if PY3 else missing_in_py2
         for func, args in (
                 ('count', ()),
                 ('cycle', ((),)),
@@ -1037,12 +1074,11 @@ class Test_selectCheckerPy(_SelectCheckerBase, unittest.TestCase):
         return selectCheckerPy(obj)
 
 
-
 @unittest.skipIf(sec_checker.selectChecker is sec_checker.selectCheckerPy,
                  "Pure Python")
 class Test_selectChecker(_SelectCheckerBase, unittest.TestCase):
 
-    def _callFUT(self, obj):
+    def _callFUT(self, obj):  # pragma: no cover
         from zope.security.checker import selectChecker
         return selectChecker(obj)
 
@@ -1068,6 +1104,7 @@ class Test_getCheckerForInstancesOf(unittest.TestCase):
 
     def test_hit(self):
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = _checkers[Foo] = object()
@@ -1097,12 +1134,13 @@ class Test_defineChecker(unittest.TestCase):
                     u'text',
                     b'binary',
                     True,
-                   ]:
+                    ]:
             self.assertRaises(TypeError, self._callFUT, obj, checker)
 
     def test_w_duplicate(self):
         from zope.exceptions import DuplicationError
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker1, checker2 = object(), object()
@@ -1112,6 +1150,7 @@ class Test_defineChecker(unittest.TestCase):
     def test_w_newstyle_class(self):
         from zope.security.checker import _checkers
         checker = object()
+
         class Foo(object):
             pass
         self._callFUT(Foo, checker)
@@ -1127,6 +1166,7 @@ class Test_defineChecker(unittest.TestCase):
     def test_w_oldstyle_class(self):
         from zope.security.checker import _checkers
         checker = object()
+
         class Foo:
             pass
         self._callFUT(Foo, checker)
@@ -1154,6 +1194,7 @@ class Test_undefineChecker(unittest.TestCase):
 
     def test_hit(self):
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         _checkers[Foo] = object()
@@ -1196,40 +1237,43 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_lhs_ok_rhs_not_called(self):
         from zope.security.checker import CheckerPublic
         from zope.security.checker import Checker
+
         class _NeverCalled(Checker):
-            def check(self, object, name): # pylint:disable=redefined-builtin
+            def check(self, object, name):  # pylint:disable=redefined-builtin
                 raise AssertionError("Never called")
 
         lhs = self._makeOther({'name': CheckerPublic})
         rhs = _NeverCalled({})
         combined = self._makeOne(lhs, rhs)
-        combined.check(object(), 'name') # no raise
+        combined.check(object(), 'name')  # no raise
 
     def test_check_lhs_unauth_rhs_ok(self):
         from zope.security.checker import CheckerPublic
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther({'name': 'view'}) # unauth
+        lhs = self._makeOther({'name': 'view'})  # unauth
         rhs = self._makeOther({'name': CheckerPublic})
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
-            combined.check(object(), 'name') #no raise
+            combined.check(object(), 'name')  # no raise
         finally:
             del thread_local.interaction
 
     def test_check_lhs_unauth_rhs_forbidden(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther({'name': 'view'}) # unauth
-        rhs = self._makeOther() # forbidden
+        lhs = self._makeOther({'name': 'view'})  # unauth
+        rhs = self._makeOther()  # forbidden
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
@@ -1241,11 +1285,12 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_lhs_unauth_rhs_unauth(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther({'name': 'view'}) # unauth
+        lhs = self._makeOther({'name': 'view'})  # unauth
         rhs = self._makeOther({'name': 'inspect'})
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
@@ -1258,16 +1303,16 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_lhs_forbidden_rhs_ok(self):
         from zope.security.checker import CheckerPublic
 
-        lhs = self._makeOther() # forbidden
+        lhs = self._makeOther()  # forbidden
         rhs = self._makeOther({'name': CheckerPublic})
         combined = self._makeOne(lhs, rhs)
-        combined.check(object(), 'name') # no raise
+        combined.check(object(), 'name')  # no raise
 
     def test_check_lhs_forbidden_rhs_forbidden(self):
         from zope.security.interfaces import Forbidden
 
-        lhs = self._makeOther() # forbidden
-        rhs = self._makeOther() # forbidden
+        lhs = self._makeOther()  # forbidden
+        rhs = self._makeOther()  # forbidden
         combined = self._makeOne(lhs, rhs)
         self.assertRaises(Forbidden,
                           combined.check, object(), 'name')
@@ -1275,11 +1320,12 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_lhs_forbidden_rhs_unauth(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther() # Forbidden
+        lhs = self._makeOther()  # Forbidden
         rhs = self._makeOther({'name': 'inspect'})
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
@@ -1292,40 +1338,43 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_setattr_lhs_ok_rhs_not_called(self):
         from zope.security.checker import CheckerPublic
         from zope.security.checker import Checker
+
         class _NeverCalled(Checker):
-            def check_setattr(self, object, name): # pylint:disable=redefined-builtin
+            def check_setattr(self, object, name):
                 raise AssertionError("Never called")
 
         lhs = self._makeOther(set_permissions={'name': CheckerPublic})
         rhs = _NeverCalled({})
         combined = self._makeOne(lhs, rhs)
-        combined.check_setattr(object(), 'name') # no raise
+        combined.check_setattr(object(), 'name')  # no raise
 
     def test_check_setattr_lhs_unauth_rhs_ok(self):
         from zope.security.checker import CheckerPublic
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther(set_permissions={'name': 'update'}) # unauth
+        lhs = self._makeOther(set_permissions={'name': 'update'})  # unauth
         rhs = self._makeOther(set_permissions={'name': CheckerPublic})
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
-            combined.check_setattr(object(), 'name') # no raise
+            combined.check_setattr(object(), 'name')  # no raise
         finally:
             del thread_local.interaction
 
     def test_check_setattr_lhs_unauth_rhs_forbidden(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther(set_permissions={'name': 'view'}) # unauth
-        rhs = self._makeOther() # forbidden
+        lhs = self._makeOther(set_permissions={'name': 'view'})  # unauth
+        rhs = self._makeOther()  # forbidden
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
@@ -1337,12 +1386,13 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_setattr_lhs_unauth_rhs_unauth(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther(set_permissions={'name': 'view'}) # unauth
-        rhs = self._makeOther(set_permissions={'name': 'inspect'}) # unauth
+        lhs = self._makeOther(set_permissions={'name': 'view'})  # unauth
+        rhs = self._makeOther(set_permissions={'name': 'inspect'})  # unauth
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
@@ -1354,16 +1404,16 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_setattr_lhs_forbidden_rhs_ok(self):
         from zope.security.checker import CheckerPublic
 
-        lhs = self._makeOther() # forbidden
+        lhs = self._makeOther()  # forbidden
         rhs = self._makeOther(set_permissions={'name': CheckerPublic})
         combined = self._makeOne(lhs, rhs)
-        combined.check_setattr(object(), 'name') # no raise
+        combined.check_setattr(object(), 'name')  # no raise
 
     def test_check_setattr_lhs_forbidden_rhs_forbidden(self):
         from zope.security.interfaces import Forbidden
 
-        lhs = self._makeOther() # forbidden
-        rhs = self._makeOther() # forbidden
+        lhs = self._makeOther()  # forbidden
+        rhs = self._makeOther()  # forbidden
         combined = self._makeOne(lhs, rhs)
         self.assertRaises(Forbidden,
                           combined.check_setattr, object(), 'name')
@@ -1371,12 +1421,13 @@ class TestCombinedChecker(QuietWatchingChecker,
     def test_check_setattr_lhs_forbidden_rhs_unauth(self):
         from zope.security.interfaces import Unauthorized
         from zope.security._definitions import thread_local
+
         class _Interaction(object):
             def checkPermission(self, obj, perm):
                 return False
 
-        lhs = self._makeOther() # forbidden
-        rhs = self._makeOther(set_permissions={'name': 'inspect'}) # unauth
+        lhs = self._makeOther()  # forbidden
+        rhs = self._makeOther(set_permissions={'name': 'inspect'})  # unauth
         combined = self._makeOne(lhs, rhs)
         thread_local.interaction = _Interaction()
         try:
@@ -1385,13 +1436,16 @@ class TestCombinedChecker(QuietWatchingChecker,
         finally:
             del thread_local.interaction
 
-@unittest.skipIf(sec_checker.WatchingCombinedChecker is sec_checker.CombinedChecker,
-                 "WatchingCombinedChecker is the default")
+
+@unittest.skipIf(
+    sec_checker.WatchingCombinedChecker is sec_checker.CombinedChecker,
+    "WatchingCombinedChecker is the default")
 class TestWatchingCombinedChecker(TestCombinedChecker):
 
     def _getTargetClass(self):
         return sec_checker.WatchingCombinedChecker
 
+
 class TestCheckerLoggingMixin(unittest.TestCase):
 
     def _getTargetClass(self):
@@ -1403,10 +1457,12 @@ class TestCheckerLoggingMixin(unittest.TestCase):
             def __init__(self, raising, stream):
                 self._file = stream
                 self._raising = raising
+
             def check(self, obj, name):
                 if self._raising:
                     raise self._raising
             check_getattr = check_setattr = check
+
         class _Derived(self._getTargetClass(), _Checker):
             pass
         return _Derived(raising, self._makeStream())
@@ -1572,12 +1628,14 @@ class Test__instanceChecker(unittest.TestCase):
 
     def test_miss(self):
         from zope.security.checker import _defaultChecker
+
         class Foo(object):
             pass
         self.assertIs(self._callFUT(Foo()), _defaultChecker)
 
     def test_hit(self):
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = _checkers[Foo] = object()
@@ -1609,8 +1667,6 @@ class Test_moduleChecker(unittest.TestCase):
         self.assertIs(self._callFUT(verify), checker)
 
 
-
-
 # Pre-geddon tests start here
 
 class TestSecurityPolicy(QuietWatchingChecker,
@@ -1645,6 +1701,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
     def _makeSecurityPolicy(self):
         from zope.interface import implementer
         from zope.security.interfaces import ISecurityPolicy
+
         @implementer(ISecurityPolicy)
         class SecurityPolicy(object):
             def checkPermission(self, permission, _object):
@@ -1655,6 +1712,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
         from zope.security.checker import defineChecker
         from zope.security.checker import NamesChecker
         old_type = self._get_old_class_type()
+
         class ClassicClass:
             __metaclass__ = old_type
         self.assertIsInstance(ClassicClass, old_type)
@@ -1664,6 +1722,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
     def test_defineChecker_newstyle_class(self):
         from zope.security.checker import defineChecker
         from zope.security.checker import NamesChecker
+
         class NewStyleClass(object):
             pass
         self.assertIsInstance(NewStyleClass, type)
@@ -1684,16 +1743,21 @@ class TestSecurityPolicy(QuietWatchingChecker,
 
     def _makeClasses(self):
         old_type = self._get_old_class_type()
+
         class OldInst:
             a = 1
+
             def b(self):
                 raise AssertionError("Never called")
             c = 2
+
             def gete(self):
                 raise AssertionError("Never called")
             e = property(gete)
+
             def __getitem__(self, x):
                 raise AssertionError("Never called")
+
             def __setitem__(self, x, v):
                 raise AssertionError("Never called")
 
@@ -1704,6 +1768,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
             # __metaclass__ = type
             def gete(self):
                 raise AssertionError("Never called")
+
             def sete(self, v):
                 raise AssertionError("Never called")
             e = property(gete, sete)
@@ -1851,10 +1916,11 @@ class TestSecurityPolicy(QuietWatchingChecker,
             self.assertEqual(next(proxy), 1)
 
     def testLayeredProxies(self):
-        #Test that a Proxy will not be re-proxied.
+        # Test that a Proxy will not be re-proxied.
         from zope.security.proxy import Proxy, getObject
         from zope.security.checker import Checker
         from zope.security.checker import NamesChecker
+
         class Base:
             __Security_checker__ = NamesChecker(['__Security_checker__'])
         base = Base()
@@ -1870,7 +1936,6 @@ class TestSecurityPolicy(QuietWatchingChecker,
         self.assertIs(proxy2, proxy1)
         self.assertIs(getObject(proxy2), base)
 
-
     def testMultiChecker(self):
         from zope.interface import Interface
 
@@ -1925,6 +1990,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
     def testAlwaysAvailable(self):
         from zope.security.checker import NamesChecker
         checker = NamesChecker(())
+
         class C(object):
             pass
         self.assertEqual(checker.check(C, '__hash__'), None)
@@ -1965,6 +2031,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
         from zope.security.checker import ProxyFactory
         from zope.security.proxy import getChecker
         from zope.security.proxy import Proxy
+
         class SomeClass(object):
             pass
         checker = NamesChecker()
@@ -1997,6 +2064,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
         from zope.security.checker import defineChecker
         from zope.security.checker import NamesChecker
         from zope.security.checker import undefineChecker
+
         class SomeClass(object):
             pass
         obj = SomeClass()
@@ -2012,6 +2080,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
     def test_ProxyFactory_using_proxy(self):
         from zope.security.checker import ProxyFactory
         from zope.security.checker import NamesChecker
+
         class SomeClass(object):
             pass
         obj = SomeClass()
@@ -2045,6 +2114,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
         from zope.security.checker import canAccess
         from zope.security.checker import canWrite
         from zope.security.checker import defineChecker
+
         class SomeClass(object):
             pass
         obj = SomeClass()
@@ -2057,24 +2127,24 @@ class TestSecurityPolicy(QuietWatchingChecker,
         # For these tests, the SecurityPolicy defined at the top of this file
         # is in place.  It is a stub.  Normally, the security policy would
         # have knowledge of interactions and participants, and would determine
-        # on the basis of the particpants and the object if a certain permission
-        # were authorized.  This stub simply says that the 'test_allowed'
-        # permission is authorized and nothing else is, for any object you pass
-        # it.
+        # on the basis of the participants and the object if a certain
+        # permission were authorized.  This stub simply says that the
+        # 'test_allowed' permission is authorized and nothing else is, for any
+        # object you pass it.
 
         # Therefore, according to the checker created here, the current
         # 'interaction' (as stubbed out in the security policy) will be allowed
         # to access and write foo, and access bar.  The interaction is
         # unauthorized for accessing baz and writing bar.  Any other access or
-        # write is not merely unauthorized but forbidden--including write access
-        # for baz.
+        # write is not merely unauthorized but forbidden--including write
+        # access for baz.
         checker = Checker(
-            {'foo':'test_allowed', # these are the read settings
-             'bar':'test_allowed',
-             'baz':'you_will_not_have_this_permission'},
-            {'foo':'test_allowed', # these are the write settings
-             'bar':'you_will_not_have_this_permission',
-             'bing':'you_will_not_have_this_permission'})
+            {'foo': 'test_allowed',  # these are the read settings
+             'bar': 'test_allowed',
+             'baz': 'you_will_not_have_this_permission'},
+            {'foo': 'test_allowed',  # these are the write settings
+             'bar': 'you_will_not_have_this_permission',
+             'bing': 'you_will_not_have_this_permission'})
         defineChecker(SomeClass, checker)
 
         # so, our hapless interaction may write and access foo...
@@ -2110,6 +2180,7 @@ class TestSecurityPolicy(QuietWatchingChecker,
         self.assertTrue(not canWrite(obj, 'bing'))
         self.assertRaises(Forbidden, canAccess, obj, 'bing')
 
+
 class TestCheckerPublic(unittest.TestCase):
 
     def test_that_pickling_CheckerPublic_retains_identity(self):
@@ -2154,14 +2225,17 @@ class TestMixinDecoratedChecker(unittest.TestCase):
     def _makeSecurityPolicy(self):
         from zope.interface import implementer
         from zope.security.interfaces import ISecurityPolicy
+
         @implementer(ISecurityPolicy)
         class RecordedSecurityPolicy(object):
             def __init__(self):
                 self._checked = []
                 self.permissions = {}
+
             def checkPermission(self, permission, _obj):
                 self._checked.append(permission)
                 return self.permissions.get(permission, True)
+
             def checkChecked(self, checked):
                 res = self._checked == checked
                 self._checked = []
@@ -2209,6 +2283,7 @@ class TestMixinDecoratedChecker(unittest.TestCase):
         from zope.security.checker import Checker
         return Checker(self.decorationGetMap, self.decorationSetMap)
 
+
 class TestCombinedCheckerMixin(QuietWatchingChecker,
                                TestMixinDecoratedChecker,
                                unittest.TestCase):
@@ -2235,7 +2310,7 @@ class TestCombinedCheckerMixin(QuietWatchingChecker,
         self.assertTrue(
             self.interaction.checkChecked(['dc_get_permission',
                                            'get_permission'])
-            )
+        )
 
         # This should raise Unauthorized instead of ForbiddenAttribute, since
         # access can be granted if you e.g. login with different credentials.
@@ -2263,6 +2338,7 @@ class TestBasicTypes(unittest.TestCase):
     def test___setitem__(self):
         from zope.security.checker import BasicTypes
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = object()
@@ -2273,6 +2349,7 @@ class TestBasicTypes(unittest.TestCase):
     def test___delitem__(self):
         from zope.security.checker import BasicTypes
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = object()
@@ -2288,6 +2365,7 @@ class TestBasicTypes(unittest.TestCase):
     def test_update(self):
         from zope.security.checker import BasicTypes
         from zope.security.checker import _checkers
+
         class Foo(object):
             pass
         checker = object()
@@ -2295,14 +2373,15 @@ class TestBasicTypes(unittest.TestCase):
         self.assertIs(BasicTypes[Foo], checker)
         self.assertIs(_checkers[Foo], checker)
 
-
     def test(self):
         from zope.security.checker import BasicTypes
         from zope.security.checker import NoProxy
         from zope.security.checker import _checkers
         from zope.security.checker import _clear
+
         class MyType(object):
             pass
+
         class MyType2(object):
             pass
 
@@ -2342,10 +2421,10 @@ class TestBasicTypes(unittest.TestCase):
         self.assertIn(str, keys)
         try:
             unicode
-        except NameError: # pragma: no cover Py3k
+        except NameError:
             pass
-        else:             # pragma: no cover Python2
-            self.assertIn(unicode, keys)
+        else:  # pragma: no cover PY2
+            self.assertIn(unicode, keys)  # noqa: F821 undefined name 'unicode'
         self.assertIn(object, keys)
         # ...
 
@@ -2353,5 +2432,6 @@ class TestBasicTypes(unittest.TestCase):
         # unwanted deletions.
         self.assertRaises(NotImplementedError, BasicTypes.clear)
 
+
 def test_suite():
     return unittest.defaultTestLoader.loadTestsFromName(__name__)
diff --git a/src/zope/security/tests/test_decorator.py b/src/zope/security/tests/test_decorator.py
index 650380d..285f7ef 100644
--- a/src/zope/security/tests/test_decorator.py
+++ b/src/zope/security/tests/test_decorator.py
@@ -64,27 +64,27 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
 
         class Foo(object):
             a = 'a'
-        fooChecker = NamesChecker(['a']) # a is public
+        fooChecker = NamesChecker(['a'])  # a is public
         defineChecker(Foo, fooChecker)
         foo = Foo()
-        fooChecker.check(foo, 'a') # no raise
+        fooChecker.check(foo, 'a')  # no raise
         self.assertRaises(ForbiddenAttribute,
                           fooChecker.check, foo, 'b')
 
         class Wrapper(ProxyBase):
             b = 'b'
             __Security_checker__ = self._makeOne()
-        wrapperChecker = NamesChecker(['b']) # b is public
+        wrapperChecker = NamesChecker(['b'])  # b is public
         defineChecker(Wrapper, wrapperChecker)
         wrapper = Wrapper(foo)
         self.assertRaises(ForbiddenAttribute,
                           wrapperChecker.check, foo, 'a')
-        wrapperChecker.check(foo, 'b') # no raise
+        wrapperChecker.check(foo, 'b')  # no raise
 
         checker = wrapper.__Security_checker__
         self.assertTrue(isinstance(checker, CombinedChecker))
-        checker.check(wrapper, 'a') # no raise
-        checker.check(wrapper, 'b') # no raise
+        checker.check(wrapper, 'a')  # no raise
+        checker.check(wrapper, 'b')  # no raise
 
     def test_only_wrapper_has_checker(self):
         from zope.proxy import ProxyBase
@@ -100,7 +100,7 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
         class Wrapper(ProxyBase):
             b = 'b'
             __Security_checker__ = self._makeOne()
-        wrapperChecker = NamesChecker(['b']) # b is public
+        wrapperChecker = NamesChecker(['b'])  # b is public
         defineChecker(Wrapper, wrapperChecker)
         wrapper = Wrapper(foo)
         self.assertTrue(wrapper.__Security_checker__ is wrapperChecker)
@@ -113,7 +113,7 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
 
         class Foo(object):
             a = 'a'
-        fooChecker = NamesChecker(['a']) # a is public
+        fooChecker = NamesChecker(['a'])  # a is public
         defineChecker(Foo, fooChecker)
         foo = Foo()
 
@@ -124,7 +124,6 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
         wrapper = Wrapper(foo)
         self.assertTrue(wrapper.__Security_checker__ is fooChecker)
 
-
     def test_both_wrapper_and_object_have_checkers_security_proxied(self):
         from zope.proxy import ProxyBase
         from zope.security.checker import CombinedChecker
@@ -134,7 +133,7 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
 
         class Foo(object):
             a = 'a'
-        fooChecker = NamesChecker(['a']) # a is public
+        fooChecker = NamesChecker(['a'])  # a is public
         defineChecker(Foo, fooChecker)
         foo = Foo()
         f_sec = ProxyFactory(foo)
@@ -142,14 +141,14 @@ class DecoratedSecurityCheckerDescriptorTests(QuietWatchingChecker,
         class Wrapper(ProxyBase):
             b = 'b'
             __Security_checker__ = self._makeOne()
-        wrapperChecker = NamesChecker(['b']) # b is public
+        wrapperChecker = NamesChecker(['b'])  # b is public
         defineChecker(Wrapper, wrapperChecker)
         w_sec = Wrapper(f_sec)
 
         checker = w_sec.__Security_checker__
         self.assertTrue(isinstance(checker, CombinedChecker))
-        checker.check(w_sec, 'a') # no raise
-        checker.check(w_sec, 'b') # no raise
+        checker.check(w_sec, 'a')  # no raise
+        checker.check(w_sec, 'b')  # no raise
 
     def test_cannot_overwrite(self):
         from zope.proxy import ProxyBase
diff --git a/src/zope/security/tests/test_location.py b/src/zope/security/tests/test_location.py
index bc5fb03..194fc52 100644
--- a/src/zope/security/tests/test_location.py
+++ b/src/zope/security/tests/test_location.py
@@ -26,6 +26,7 @@ class LocationSecurityProxyTests(QuietWatchingChecker,
         from zope.security.checker import defineChecker
         from zope.security.checker import NamesChecker
         from zope.security.proxy import ProxyFactory
+
         class Unlocated(object):
             a = 'a'
         unlocated = Unlocated()
diff --git a/src/zope/security/tests/test_management.py b/src/zope/security/tests/test_management.py
index 93ce19d..78dd78d 100644
--- a/src/zope/security/tests/test_management.py
+++ b/src/zope/security/tests/test_management.py
@@ -83,7 +83,7 @@ class Test(unittest.TestCase):
         from zope.security.management import newInteraction
         from zope.security.management import queryInteraction
         newInteraction()
-        interaction = queryInteraction()
+        queryInteraction()
         endInteraction()
         self.assertEqual(queryInteraction(), None)
         endInteraction()
@@ -106,7 +106,7 @@ class Test(unittest.TestCase):
         from zope.security.management import restoreInteraction
         newInteraction()
         self.assertTrue(queryInteraction() is not None)
-        restoreInteraction() # restore to no interaction
+        restoreInteraction()  # restore to no interaction
         self.assertTrue(queryInteraction() is None)
 
     def test_restoreInteraction_after_neither(self):
@@ -170,7 +170,6 @@ class Test(unittest.TestCase):
         self.assertEqual(checkPermission(None, obj), True)
         self.assertEqual(checkPermission(CheckerPublic, obj), True)
 
-
     def test_system_user(self):
         from zope.interface.verify import verifyObject
         from zope.security.interfaces import IPrincipal
diff --git a/src/zope/security/tests/test_metaconfigure.py b/src/zope/security/tests/test_metaconfigure.py
index 20477c0..c8631e9 100644
--- a/src/zope/security/tests/test_metaconfigure.py
+++ b/src/zope/security/tests/test_metaconfigure.py
@@ -16,6 +16,7 @@
 import unittest
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 class Test_dottedName(unittest.TestCase):
 
     def _callFUT(self, obj):
@@ -40,7 +41,7 @@ class ClassDirectiveTests(unittest.TestCase):
     def _makeOne(self, _context, class_):
         return self._getTargetClass()(_context, class_)
 
-    #def test_ctor_non_class(self): TODO  needs better guard in __init__
+    # def test_ctor_non_class(self): TODO  needs better guard in __init__
 
     def test_implements_empty(self):
         context = DummyZCMLContext()
@@ -52,6 +53,7 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.component.interface import provideInterface
         from zope.interface import Interface
         from zope.interface import classImplements
+
         class IFoo(Interface):
             pass
         context = DummyZCMLContext()
@@ -59,7 +61,7 @@ class ClassDirectiveTests(unittest.TestCase):
         directive.implements(context, [IFoo])
         self.assertEqual(len(context._actions), 2)
         self.assertEqual(context._actions[0]['discriminator'][:2],
-                         ('ContentDirective', Foo, )) #3rd is object()
+                         ('ContentDirective', Foo, ))  # 3rd is object()
         self.assertTrue(context._actions[0]['callable'] is classImplements)
         self.assertEqual(context._actions[0]['args'], (Foo, IFoo))
         self.assertTrue(context._actions[1]['discriminator'] is None)
@@ -71,8 +73,10 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.component.interface import provideInterface
         from zope.interface import Interface
         from zope.interface import classImplements
+
         class IFoo(Interface):
             pass
+
         class IBar(Interface):
             pass
         context = DummyZCMLContext()
@@ -80,7 +84,7 @@ class ClassDirectiveTests(unittest.TestCase):
         directive.implements(context, [IFoo, IBar])
         self.assertEqual(len(context._actions), 4)
         self.assertEqual(context._actions[0]['discriminator'][:2],
-                         ('ContentDirective', Foo, )) #3rd is object()
+                         ('ContentDirective', Foo, ))  # 3rd is object()
         self.assertTrue(context._actions[0]['callable'] is classImplements)
         self.assertEqual(context._actions[0]['args'], (Foo, IFoo))
         self.assertTrue(context._actions[1]['discriminator'] is None)
@@ -88,7 +92,7 @@ class ClassDirectiveTests(unittest.TestCase):
         self.assertEqual(context._actions[1]['args'],
                          ('zope.security.tests.test_metaconfigure.IFoo', IFoo))
         self.assertEqual(context._actions[2]['discriminator'][:2],
-                         ('ContentDirective', Foo, )) #3rd is object()
+                         ('ContentDirective', Foo, ))  # 3rd is object()
         self.assertTrue(context._actions[2]['callable'] is classImplements)
         self.assertEqual(context._actions[2]['args'], (Foo, IBar))
         self.assertTrue(context._actions[3]['discriminator'] is None)
@@ -98,6 +102,7 @@ class ClassDirectiveTests(unittest.TestCase):
 
     def test_require_only_like_class(self):
         from zope.security.protectclass import protectLikeUnto
+
         class Bar(object):
             pass
         context = DummyZCMLContext()
@@ -105,7 +110,7 @@ class ClassDirectiveTests(unittest.TestCase):
         directive.require(context, like_class=Bar)
         self.assertEqual(len(context._actions), 1)
         self.assertEqual(context._actions[0]['discriminator'][:2],
-                         ('mimic', Foo, )) #3rd is object()
+                         ('mimic', Foo, ))  # 3rd is object()
         self.assertTrue(context._actions[0]['callable'] is protectLikeUnto)
         self.assertEqual(context._actions[0]['args'], (Foo, Bar))
 
@@ -120,14 +125,15 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.configuration.exceptions import ConfigurationError
         context = DummyZCMLContext()
         directive = self._makeOne(context, Foo)
-        self.assertRaises(ConfigurationError,
-                          directive.require, context, attributes=('foo', 'bar'))
+        with self.assertRaises(ConfigurationError):
+            directive.require(context, attributes=('foo', 'bar'))
 
     def test_require_w_single_interface(self):
         from zope.component.interface import provideInterface
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.protectclass import protectName
+
         class IFoo(Interface):
             bar = Attribute("Bar")
             baz = Attribute("Baz")
@@ -153,13 +159,16 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.protectclass import protectName
+
         class IFoo(Interface):
             bar = Attribute("Bar")
+
         class IBar(Interface):
             baz = Attribute("Baz")
         context = DummyZCMLContext()
         directive = self._makeOne(context, Foo)
-        directive.require(context, permission='testing', interface=[IFoo, IBar])
+        directive.require(context, permission='testing',
+                          interface=[IFoo, IBar])
         self.assertEqual(len(context._actions), 4)
         self.assertEqual(context._actions[0]['discriminator'],
                          ('protectName', Foo, 'bar'))
@@ -215,6 +224,7 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.schema import Field
         from zope.interface import Interface
         from zope.security.protectclass import protectSetAttribute
+
         class IFoo(Interface):
             bar = Field(u"Bar")
             baz = Field(u"Baz")
@@ -239,6 +249,7 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.component.interface import provideInterface
         from zope.interface import Attribute
         from zope.interface import Interface
+
         class IFoo(Interface):
             bar = Attribute("Bar")
         context = DummyZCMLContext()
@@ -254,6 +265,7 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.component.interface import provideInterface
         from zope.schema import Field
         from zope.interface import Interface
+
         class IFoo(Interface):
             bar = Field(u"Bar", readonly=True)
         context = DummyZCMLContext()
@@ -276,6 +288,7 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.protectclass import protectName
+
         class IFoo(Interface):
             bar = Attribute("Bar")
             baz = Attribute("Baz")
@@ -303,8 +316,10 @@ class ClassDirectiveTests(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.protectclass import protectName
+
         class IFoo(Interface):
             bar = Attribute("Bar")
+
         class IBar(Interface):
             baz = Attribute("Baz")
         context = DummyZCMLContext()
@@ -489,6 +504,7 @@ class Test_allow(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.metaconfigure import protectModule
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         context = DummyZCMLContext()
@@ -506,6 +522,7 @@ class Test_allow(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.metaconfigure import protectModule
+
         class IFoo(Interface):
             bar = Attribute('Bar')
             baz = Attribute('Baz')
@@ -586,6 +603,7 @@ class Test_requre(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.metaconfigure import protectModule
+
         class IFoo(Interface):
             bar = Attribute('Bar')
         context = DummyZCMLContext()
@@ -604,6 +622,7 @@ class Test_requre(unittest.TestCase):
         from zope.interface import Attribute
         from zope.interface import Interface
         from zope.security.metaconfigure import protectModule
+
         class IFoo(Interface):
             bar = Attribute('Bar')
             baz = Attribute('Baz')
diff --git a/src/zope/security/tests/test_permission.py b/src/zope/security/tests/test_permission.py
index 82ddea2..9e03496 100644
--- a/src/zope/security/tests/test_permission.py
+++ b/src/zope/security/tests/test_permission.py
@@ -17,6 +17,7 @@ import unittest
 from zope.component.testing import PlacelessSetup
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 class PermissionTests(unittest.TestCase):
 
     def _getTargetClass(self):
@@ -62,7 +63,7 @@ class Test_checkPermission(PlacelessSetup, unittest.TestCase):
 
     def test_w_CheckerPublic(self):
         from zope.security.checker import CheckerPublic
-        self._callFUT(None, CheckerPublic) # no raise
+        self._callFUT(None, CheckerPublic)  # no raise
 
     def test_miss(self):
         self.assertRaises(ValueError, self._callFUT, None, 'nonesuch')
@@ -72,7 +73,7 @@ class Test_checkPermission(PlacelessSetup, unittest.TestCase):
         from zope.security.interfaces import IPermission
         permission = object()
         provideUtility(permission, IPermission, 'testing')
-        self._callFUT(None, 'testing') # no raise
+        self._callFUT(None, 'testing')  # no raise
 
 
 class Test_allPermissions(PlacelessSetup, unittest.TestCase):
@@ -143,7 +144,6 @@ class Test_PermissionsVocabulary(PlacelessSetup, unittest.TestCase):
         from zope.security.interfaces import IPermission
         from zope.schema import getValidationErrors
 
-
         xmlconfig.file('configure.zcml', zope.security)
         vocabulary = self._callFUT()
         vocabulary = sorted(vocabulary, key=lambda term: term.token)
@@ -155,6 +155,7 @@ class Test_PermissionsVocabulary(PlacelessSetup, unittest.TestCase):
             verifyObject(IPermission, p)
             self.assertEqual([], getValidationErrors(IPermission, p))
 
+
 class Test_PermissionIdsVocabulary(PlacelessSetup, unittest.TestCase):
 
     def _callFUT(self):
diff --git a/src/zope/security/tests/test_protectclass.py b/src/zope/security/tests/test_protectclass.py
index 759f151..2f8e490 100644
--- a/src/zope/security/tests/test_protectclass.py
+++ b/src/zope/security/tests/test_protectclass.py
@@ -16,6 +16,7 @@
 import unittest
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 class Test_protectName(unittest.TestCase):
 
     def setUp(self):
diff --git a/src/zope/security/tests/test_proxy.py b/src/zope/security/tests/test_proxy.py
index cecac86..ef664ee 100644
--- a/src/zope/security/tests/test_proxy.py
+++ b/src/zope/security/tests/test_proxy.py
@@ -17,18 +17,21 @@ import unittest
 
 from zope.security._compat import PYTHON2, PURE_PYTHON
 
+
 def _skip_if_not_Py2(testfunc):
     return unittest.skipUnless(PYTHON2, "Only on Py2")(testfunc)
 
 # pylint:disable=protected-access,eval-used,too-many-lines,too-many-public-methods
 
-if not PYTHON2: # pragma: no cover (Python 3)
+
+if not PYTHON2:  # pragma: PY3
     def coerce(*args):
         raise NotImplementedError("Not on Python 3")
     cmp = coerce
     long = int
     unicode = str
 
+
 class AbstractProxyTestBase(object):
 
     # pylint:disable=no-member,blacklisted-name
@@ -67,6 +70,7 @@ class AbstractProxyTestBase(object):
 
     def test___getattr___w_checker_unauthorized(self):
         from zope.security.interfaces import Unauthorized
+
         class Foo(object):
             bar = 'Bar'
         target = Foo()
@@ -77,6 +81,7 @@ class AbstractProxyTestBase(object):
 
     def test___getattr___w_checker_forbidden_attribute(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class Foo(object):
             bar = 'Bar'
         target = Foo()
@@ -90,6 +95,7 @@ class AbstractProxyTestBase(object):
     def test__getattr__w_checker_ok_dynamic_attribute_called_once(self):
         class Dynamic(object):
             count = 0
+
             def __getattr__(self, name):
                 self.count += 1
                 if self.count == 1:
@@ -118,6 +124,7 @@ class AbstractProxyTestBase(object):
 
     def test___setattr___w_checker_unauthorized(self):
         from zope.security.interfaces import Unauthorized
+
         class Foo(object):
             bar = 'Bar'
         target = Foo()
@@ -128,6 +135,7 @@ class AbstractProxyTestBase(object):
 
     def test___setattr___w_checker_forbidden_attribute(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class Foo(object):
             bar = 'Bar'
         target = Foo()
@@ -150,6 +158,7 @@ class AbstractProxyTestBase(object):
 
     def test___delattr___w_checker_unauthorized(self):
         from zope.security.interfaces import Unauthorized
+
         class Foo(object):
             def __init__(self):
                 self.bar = 'Bar'
@@ -162,6 +171,7 @@ class AbstractProxyTestBase(object):
 
     def test___delattr___w_checker_forbidden_attribute(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class Foo(object):
             def __init__(self):
                 self.bar = 'Bar'
@@ -192,9 +202,10 @@ class AbstractProxyTestBase(object):
 
     def test___str___fails_return(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class CustomStr(object):
             def __str__(self):
-                "<CustomStr>" # Docstring, not a return
+                "<CustomStr>"  # Docstring, not a return
 
         target = CustomStr()
         checker = DummyChecker(ForbiddenAttribute, allowed=('__str__'))
@@ -224,12 +235,14 @@ class AbstractProxyTestBase(object):
 
     def test___str___falls_through_to_repr_when_both_allowed(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class CustomRepr(object):
             def __repr__(self):
                 return "<CustomRepr>"
 
         target = CustomRepr()
-        checker = DummyChecker(ForbiddenAttribute, allowed=("__str__", '__repr__'))
+        checker = DummyChecker(
+            ForbiddenAttribute, allowed=("__str__", '__repr__'))
         proxy = self._makeOne(target, checker)
         self.assertEqual(repr(proxy), "<CustomRepr>")
         self.assertEqual(str(target), "<CustomRepr>")
@@ -237,6 +250,7 @@ class AbstractProxyTestBase(object):
 
     def test___str___doesnot_fall_through_to_repr_when_str_not_allowed(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class CustomRepr(object):
             def __repr__(self):
                 return "<CustomRepr>"
@@ -250,6 +264,7 @@ class AbstractProxyTestBase(object):
 
     def test___str___doesnot_fall_through_to_repr_when_repr_not_allowed(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class CustomRepr(object):
             def __repr__(self):
                 return "<CustomRepr>"
@@ -263,9 +278,10 @@ class AbstractProxyTestBase(object):
 
     def test___str___falls_through_to_repr_but_repr_fails_return(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class CustomRepr(object):
             def __repr__(self):
-                "<CustomRepr>" # Docstring, not a return
+                "<CustomRepr>"  # Docstring, not a return
 
         target = CustomRepr()
         checker = DummyChecker(ForbiddenAttribute, allowed=('__repr__'))
@@ -276,62 +292,62 @@ class AbstractProxyTestBase(object):
             repr(proxy)
 
     @_skip_if_not_Py2
-    def test___cmp___w_self(self):
+    def test___cmp___w_self(self):  # pragma: no cover
         target = object()
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertEqual(cmp(proxy, proxy), 0)
 
     @_skip_if_not_Py2
-    def test___cmp___w_target(self):
+    def test___cmp___w_target(self):  # pragma: no cover
         target = object()
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertEqual(cmp(proxy, target), 0)
 
     @_skip_if_not_Py2
-    def test___cmp___w_other(self):
+    def test___cmp___w_other(self):  # pragma: no cover
         target = object()
         other = object()
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertNotEqual(cmp(proxy, other), 0)
 
     @_skip_if_not_Py2
-    def test___cmp___w_other_proxy(self):
+    def test___cmp___w_other_proxy(self):  # pragma: no cover
         target = object()
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         o_proxy = self._makeOne(target, checker)
         self.assertEqual(cmp(proxy, o_proxy), 0)
 
     def test__le__(self):
         target = 1
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertTrue(proxy <= 1)
 
     def test__ne__(self):
         target = 1
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertFalse(proxy != 1)
 
     def test__ge__(self):
         target = 1
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertTrue(proxy >= 1)
 
     def test__gt__(self):
         target = 1
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertTrue(proxy > 0)
 
     def test___hash___w_self(self):
         target = object()
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         proxy = self._makeOne(target, checker)
         self.assertEqual(hash(proxy), hash(target))
 
@@ -348,6 +364,7 @@ class AbstractProxyTestBase(object):
 
     def test___call___w_checker_unauthorized(self):
         from zope.security.interfaces import Unauthorized
+
         class Foo(object):
             def __call__(self):
                 raise AssertionError("Never called")
@@ -359,6 +376,7 @@ class AbstractProxyTestBase(object):
 
     def test___call___w_checker_forbidden_attribute(self):
         from zope.security.interfaces import ForbiddenAttribute
+
         class Foo(object):
             def __call__(self):
                 raise AssertionError("Never called")
@@ -399,7 +417,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__float__')
 
     @_skip_if_not_Py2
-    def test___long___w_checker_allows(self):
+    def test___long___w_checker_allows(self):  # pragma: no cover
         target = 3.0
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -407,7 +425,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__long__')
 
     @_skip_if_not_Py2
-    def test___long___w_checker_forbids(self):
+    def test___long___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = 3
         checker = DummyChecker(ForbiddenAttribute)
@@ -416,7 +434,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__long__')
 
     @_skip_if_not_Py2
-    def test___oct___w_checker_allows(self):
+    def test___oct___w_checker_allows(self):  # pragma: no cover
         target = 3
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -424,7 +442,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__oct__')
 
     @_skip_if_not_Py2
-    def test___oct___w_checker_forbids(self):
+    def test___oct___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = 3
         checker = DummyChecker(ForbiddenAttribute)
@@ -433,7 +451,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__oct__')
 
     @_skip_if_not_Py2
-    def test___hex___w_checker_allows(self):
+    def test___hex___w_checker_allows(self):  # pragma: no cover
         target = 3
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -441,7 +459,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__hex__')
 
     @_skip_if_not_Py2
-    def test___hex___w_checker_forbids(self):
+    def test___hex___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = 3
         checker = DummyChecker(ForbiddenAttribute)
@@ -599,20 +617,24 @@ class AbstractProxyTestBase(object):
         self.assertRaises(ForbiddenAttribute, lambda: pow(x, proxy))
         self.assertEqual(checker._checked, '__rpow__')
 
-    def test___pow___w_z_proxied_allowed(self):
+    @unittest.expectedFailure
+    def test___pow___w_z_proxied_allowed2(self):
+        # There is no method `__3pow__` - is this test obsolete?
         x, y, z = 3, 4, 7
         checker = DummyChecker()
         proxy = self._makeOne(z, checker)
         self.assertEqual(pow(x, y, proxy), pow(x, y, z))
-        self.assertEqual(checker._checked, '__3pow__')
+        self.assertEqual(checker._checked, '__3pow__')  # pragma: no cover
 
-    def test___pow___w_z_proxied_forbidden(self):
+    @unittest.expectedFailure
+    def test___pow___w_z_proxied_forbidden2(self):
+        # There is no method `__3pow__` - is this test obsolete?
         from zope.security.interfaces import ForbiddenAttribute
         x, y, z = 3, 4, 7
         checker = DummyChecker(ForbiddenAttribute)
         proxy = self._makeOne(z, checker)
         self.assertRaises(ForbiddenAttribute, lambda: pow(x, y, proxy))
-        self.assertEqual(checker._checked, '__3pow__')
+        self.assertEqual(checker._checked, '__3pow__')  # pragma: no cover
 
     def test___neg___w_checker_allows(self):
         target = 3
@@ -756,7 +778,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__or__')
 
     @_skip_if_not_Py2
-    def test___coerce___w_checker_allows(self):
+    def test___coerce___w_checker_allows(self):  # pragma: no cover
         target = 3
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -764,7 +786,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__coerce__')
 
     @_skip_if_not_Py2
-    def test___coerce___w_checker_forbids(self):
+    def test___coerce___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = 3
         checker = DummyChecker(ForbiddenAttribute)
@@ -785,6 +807,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __iadd__(self, rhs):
                 self.value += rhs
                 return self
@@ -818,6 +841,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __isub__(self, rhs):
                 self.value -= rhs
                 return self
@@ -851,6 +875,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __imul__(self, rhs):
                 self.value *= rhs
                 return self
@@ -884,6 +909,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __idiv__(self, rhs):
                 self.value /= rhs
                 return self
@@ -918,6 +944,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __itruediv__(self, rhs):
                 self.value /= rhs
                 return self
@@ -952,6 +979,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __ifloordiv__(self, rhs):
                 self.value //= rhs
                 return self
@@ -985,6 +1013,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __imod__(self, rhs):
                 self.value %= rhs
                 return self
@@ -1018,6 +1047,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __ipow__(self, rhs):
                 self.value **= rhs
                 return self
@@ -1051,6 +1081,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __ilshift__(self, rhs):
                 self.value <<= rhs
                 return self
@@ -1084,6 +1115,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __irshift__(self, rhs):
                 self.value >>= rhs
                 return self
@@ -1117,6 +1149,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __iand__(self, rhs):
                 self.value &= rhs
                 return self
@@ -1150,6 +1183,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __ixor__(self, rhs):
                 self.value ^= rhs
                 return self
@@ -1185,6 +1219,7 @@ class AbstractProxyTestBase(object):
         class Foo(object):
             def __init__(self, value):
                 self.value = value
+
             def __ior__(self, rhs):
                 self.value |= rhs
                 return self
@@ -1290,6 +1325,7 @@ class AbstractProxyTestBase(object):
         target = [0, 1, 2]
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
+
         def _try():
             proxy[4] = 7
         self.assertRaises(IndexError, _try)
@@ -1300,13 +1336,14 @@ class AbstractProxyTestBase(object):
         target = [0, 1, 2]
         checker = DummyChecker(ForbiddenAttribute)
         proxy = self._makeOne(target, checker)
+
         def _try():
             proxy[4] = 7
         self.assertRaises(ForbiddenAttribute, _try)
         self.assertEqual(checker._checked, '__setitem__')
 
     @_skip_if_not_Py2
-    def test___getslice___w_checker_allows(self):
+    def test___getslice___w_checker_allows(self):  # pragma: no cover
         target = [0, 1, 2]
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -1316,11 +1353,13 @@ class AbstractProxyTestBase(object):
     def test___getslice___error_propagates(self):
         class Missing(Exception):
             pass
+
         class Get(object):
             def __getitem__(self, x):
-                raise Missing('__getitem__') # pragma: no cover (only py3)
-            def __getslice__(self, start, stop):
-                raise Missing("__getslice__")
+                raise Missing('__getitem__')
+
+            def __getslice__(self, start, stop):  # PY2
+                raise Missing("__getslice__")  # pragma: no cover
         target = Get()
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -1333,6 +1372,7 @@ class AbstractProxyTestBase(object):
     def test___getslice___dne_uses_getitem(self):
         class Missing(Exception):
             pass
+
         class Get(object):
             def __getitem__(self, x):
                 raise Missing('__getitem__')
@@ -1347,7 +1387,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, self.getslice)
 
     @_skip_if_not_Py2
-    def test___getslice___w_checker_forbids(self):
+    def test___getslice___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = [0, 1, 2]
         checker = DummyChecker(ForbiddenAttribute)
@@ -1356,7 +1396,7 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__getslice__')
 
     @_skip_if_not_Py2
-    def test___setslice___w_checker_allows(self):
+    def test___setslice___w_checker_allows(self):  # pragma: no cover
         target = [0, 1, 2]
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -1365,11 +1405,12 @@ class AbstractProxyTestBase(object):
         self.assertEqual(checker._checked, '__setslice__')
 
     @_skip_if_not_Py2
-    def test___setslice___w_checker_forbids(self):
+    def test___setslice___w_checker_forbids(self):  # pragma: no cover
         from zope.security.interfaces import ForbiddenAttribute
         target = [0, 1, 2]
         checker = DummyChecker(ForbiddenAttribute)
         proxy = self._makeOne(target, checker)
+
         def _try():
             proxy[1:3] = [3, 4]
         self.assertRaises(ForbiddenAttribute, _try)
@@ -1378,11 +1419,13 @@ class AbstractProxyTestBase(object):
     def test___setslice___error_propagates(self):
         class Missing(Exception):
             pass
+
         class Set(object):
             def __setitem__(self, k, v):
-                raise Missing('__setitem__') # pragma: no cover (only py3)
-            def __setslice__(self, start, stop, value):
-                raise Missing("__setslice__")
+                raise Missing('__setitem__')
+
+            def __setslice__(self, start, stop, value):  # PY2
+                raise Missing("__setslice__")  # pragma: no cover
         target = Set()
         checker = DummyChecker()
         proxy = self._makeOne(target, checker)
@@ -1395,6 +1438,7 @@ class AbstractProxyTestBase(object):
     def test___setslice___dne_uses_setitem(self):
         class Missing(Exception):
             pass
+
         class Set(object):
             def __setitem__(self, k, v):
                 raise Missing('__setitem__')
@@ -1443,6 +1487,7 @@ class AbstractProxyTestBase(object):
         target = {'a': 0, 'b': 1, 'c': 2}
         checker = DummyChecker(ForbiddenAttribute)
         proxy = self._makeOne(target, checker)
+
         def _try():
             proxy['a'] = 7
         self.assertRaises(ForbiddenAttribute, _try)
@@ -1451,7 +1496,7 @@ class AbstractProxyTestBase(object):
     binops = [
         "x+y", "x-y", "x*y", "x/y", "divmod(x, y)", "x**y", "x//y",
         "x<<y", "x>>y", "x&y", "x|y", "x^y",
-        ]
+    ]
 
     def test_binops(self):
         from zope.security.proxy import removeSecurityProxy
@@ -1467,28 +1512,27 @@ class AbstractProxyTestBase(object):
                         self.assertEqual(removeSecurityProxy(eval(expr)), z,
                                          "x=%r; y=%r; expr=%r" % (x, y, expr))
 
-
     @_skip_if_not_Py2
-    def test___unicode___allowed_by_default(self):
+    def test___unicode___allowed_by_default(self):  # pragma: no cover
         # https://github.com/zopefoundation/zope.security/issues/10
         class Foo(object):
             def __unicode__(self):
                 return u'I am unicode'
 
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         target = Foo()
         proxy = self._makeOne(target, checker)
         self.assertEqual(unicode(target), u'I am unicode')
         self.assertEqual(unicode(target), unicode(proxy))
 
     @_skip_if_not_Py2
-    def test___unicode___falls_through_to_str_by_default(self):
+    def test___unicode___falls_through_to_str_by_default(self):  # pragma: no cover # noqa: E501 line too long
         # https://github.com/zopefoundation/zope.security/issues/10
         class Foo(object):
             def __str__(self):
                 return 'I am str'
 
-        checker = object() # checker not consulted
+        checker = object()  # checker not consulted
         target = Foo()
         proxy = self._makeOne(target, checker)
         self.assertEqual(unicode(target), u'I am str')
@@ -1497,11 +1541,12 @@ class AbstractProxyTestBase(object):
         self.assertIsInstance(unicode(proxy), unicode)
 
     @_skip_if_not_Py2
-    def test___unicode___falls_through_to_str_even_if_str_not_allowed(self):
+    def test___unicode___falls_through_to_str_even_if_str_not_allowed(self):  # pragma: no cover # noqa: E501 line too long
         # https://github.com/zopefoundation/zope.security/issues/10
         # Note that this is inconsistent with str() and probably not a good
         # idea overall, so this test is strictly a regression test.
         from zope.security.interfaces import ForbiddenAttribute
+
         class Foo(object):
             def __str__(self):
                 return 'I am str'
@@ -1525,7 +1570,7 @@ class AbstractProxyTestBase(object):
 class ProxyCTests(AbstractProxyTestBase,
                   unittest.TestCase):
 
-    def _getTargetClass(self):
+    def _getTargetClass(self):  # pragma: no cover
         from zope.security.proxy import _Proxy
         return _Proxy
 
@@ -1548,6 +1593,7 @@ class ProxyPyTests(AbstractProxyTestBase,
     def test_access_checker_from_subclass(self):
         target = object()
         checker = DummyChecker()
+
         class Sub(self._getTargetClass()):
             def get_checker(self):
                 return self._checker
@@ -1568,6 +1614,7 @@ class ProxyPyTests(AbstractProxyTestBase,
         target = object()
         checker = object()
         proxy = self._makeOne(target, checker)
+
         def test():
             del proxy._wrapped
         self.assertRaises(AttributeError, test)
@@ -1576,6 +1623,7 @@ class ProxyPyTests(AbstractProxyTestBase,
         target = object()
         checker = object()
         proxy = self._makeOne(target, checker)
+
         def test():
             del proxy._checker
         self.assertRaises(AttributeError, test)
@@ -1616,7 +1664,8 @@ class ProxyPyTests(AbstractProxyTestBase,
         orig_builtin_isinstance = zope.security.proxy._builtin_isinstance
         zope.security.proxy._builtin_isinstance = None
         try:
-            self.assertRaises(TypeError, zope.security.proxy.getObjectPy, proxy)
+            self.assertRaises(
+                TypeError, zope.security.proxy.getObjectPy, proxy)
         finally:
             zope.security.proxy._builtin_isinstance = orig_builtin_isinstance
 
@@ -1646,17 +1695,21 @@ class ProxyPyTests(AbstractProxyTestBase,
         proxy = self._makeOne(module, DummyChecker())
         self.assertEqual(WithModule.__module__, proxy.__module__)
 
+
 class DummyChecker(object):
     _proxied = _checked = None
+
     def __init__(self, raising=None, allowed=()):
         self._raising = raising
         self._allowed = allowed
+
     def check(self, target, name):
         self._checked = name
         if name not in self._allowed:
             if self._raising is not None:
                 raise self._raising(name)
     check_getattr = check_setattr = check
+
     def proxy(self, value):
         self._proxied = value
         return value
@@ -1703,6 +1756,7 @@ class Test_isinstance(unittest.TestCase):
     def test_w_proxied_object(self):
         from zope.security.checker import Checker
         from zope.security.proxy import Proxy
+
         class Foo(object):
             pass
         target = Foo()
@@ -1717,7 +1771,7 @@ class Checker(object):
 
     ok = 1
 
-    unproxied_types = {str,}
+    unproxied_types = {str, }
 
     def check_getattr(self, _object, name):
         if name not in ("foo", "next", "__class__", "__name__", "__module__"):
@@ -1741,32 +1795,45 @@ class Checker(object):
 class Something:
     def __init__(self):
         self.foo = [1, 2, 3]
+
     def __getitem__(self, key):
         return self.foo[key]
+
     def __setitem__(self, key, value):
         self.foo[key] = value
+
     def __delitem__(self, key):
         del self.foo[key]
+
     def __call__(self, arg):
         return 42
+
     def __eq__(self, other):
         return self is other
+
     def __hash__(self):
         return 42
+
     def __iter__(self):
         return self
+
     def __next__(self):
-        return 42 # Infinite sequence
+        return 42  # Infinite sequence
     next = __next__
+
     def __len__(self):
         return 42
-    def __nonzero__(self):
-        return 1
-    def __getslice__(self, i, j):
-        return [42]
-    def __setslice__(self, i, j, value):
-        if value != [42]:
+
+    def __nonzero__(self):  # PY2
+        return 1  # pragma: no cover
+
+    def __getslice__(self, i, j):  # PY2
+        return [42]  # pragma: no cover
+
+    def __setslice__(self, i, j, value):  # PY2
+        if value != [42]:  # pragma: no cover
             raise AssertionError("Value should be [42]")
+
     def __contains__(self, x):
         return x == 42
 
@@ -1800,7 +1867,7 @@ class ProxyFactoryTests(unittest.TestCase):
         self.assertTrue(s.startswith(
             "<security proxied %s.%s instance at"
             % (x.__class__.__module__, x.__class__.__name__)),
-                        s)
+            s)
 
     def testRepr(self):
         from zope.security.proxy import ProxyFactory
@@ -1814,7 +1881,7 @@ class ProxyFactoryTests(unittest.TestCase):
         self.assertTrue(s.startswith(
             "<security proxied %s.%s instance at"
             % (x.__class__.__module__, x.__class__.__name__)),
-                        s)
+            s)
 
     def testGetAttrOK(self):
         from zope.security.proxy import removeSecurityProxy
@@ -1867,8 +1934,8 @@ class ProxyFactoryTests(unittest.TestCase):
     def testRichCompareOK(self):
         self.assertTrue(self.p == self.x)
 
-##     def testRichCompareFail(self):
-##         self.shouldFail(lambda: self.p == self.x)
+#    def testRichCompareFail(self):
+#        self.shouldFail(lambda: self.p == self.x)
 
     def testIterOK(self):
         from zope.security.proxy import removeSecurityProxy
@@ -1884,23 +1951,23 @@ class ProxyFactoryTests(unittest.TestCase):
         self.shouldFail(self.p.next)
 
     @_skip_if_not_Py2
-    def testCompareOK(self):
+    def testCompareOK(self):  # pragma: no cover
         self.assertEqual(cmp(self.p, self.x), 0)
 
-##     def testCompareFail(self):
-##         self.shouldFail(cmp, self.p, self.x)
+#    def testCompareFail(self):
+#        self.shouldFail(cmp, self.p, self.x)
 
     def testHashOK(self):
         self.assertEqual(hash(self.p), hash(self.x))
 
-##     def testHashFail(self):
-##         self.shouldFail(hash, self.p)
+#   def testHashFail(self):
+#       self.shouldFail(hash, self.p)
 
     def testNonzeroOK(self):
         self.assertEqual(not self.p, 0)
 
-##     def testNonzeroFail(self):
-##         self.shouldFail(lambda: not self.p)
+#    def testNonzeroFail(self):
+#        self.shouldFail(lambda: not self.p)
 
     def testLenOK(self):
         self.assertEqual(len(self.p), 42)
@@ -1909,7 +1976,7 @@ class ProxyFactoryTests(unittest.TestCase):
         self.shouldFail(len, self.p)
 
     @_skip_if_not_Py2
-    def testSliceOK(self):
+    def testSliceOK(self):  # pragma: no cover
         from zope.security.proxy import removeSecurityProxy
         self.assertEqual(removeSecurityProxy(self.p[:]), [42])
 
@@ -1938,9 +2005,9 @@ class ProxyFactoryTests(unittest.TestCase):
         from zope.security.proxy import getChecker
         self.assertEqual(self.c, getChecker(self.p))
 
-
     def testProxiedClassicClassAsDictKey(self):
         from zope.security.proxy import ProxyFactory
+
         class C(object):
             pass
         d = {C: C()}
@@ -1949,6 +2016,7 @@ class ProxyFactoryTests(unittest.TestCase):
 
     def testProxiedNewClassAsDictKey(self):
         from zope.security.proxy import ProxyFactory
+
         class C(object):
             pass
         d = {C: C()}
@@ -1957,7 +2025,7 @@ class ProxyFactoryTests(unittest.TestCase):
 
     unops = ["-x", "+x", "abs(x)", "~x", "int(x)", "float(x)"]
     if PYTHON2:
-        unops.append("long(x)")
+        unops.append("long(x)")  # pragma: no cover
 
     def _make_eval(self, expr, locs):
         def _eval(*args):
@@ -1973,7 +2041,7 @@ class ProxyFactoryTests(unittest.TestCase):
         from zope.security.proxy import removeSecurityProxy
         self.c.unproxied_types = {str, int, float}
         if PYTHON2:
-            self.c.unproxied_types.add(long)
+            self.c.unproxied_types.add(long)  # pragma: no cover
 
         for expr in self.unops:
             x = 1
@@ -1986,7 +2054,7 @@ class ProxyFactoryTests(unittest.TestCase):
             self.shouldFail(self._make_eval(expr, locals()), x)
 
     @_skip_if_not_Py2
-    def test_odd_unops(self):
+    def test_odd_unops(self):  # pragma: no cover
         # unops that don't return a proxy
         P = self.c.proxy
         for func in (
@@ -1999,7 +2067,7 @@ class ProxyFactoryTests(unittest.TestCase):
     binops = [
         "x+y", "x-y", "x*y", "x/y", "divmod(x, y)", "x**y", "x//y",
         "x<<y", "x>>y", "x&y", "x|y", "x^y",
-        ]
+    ]
 
     def test_binops(self):
         from zope.security.proxy import removeSecurityProxy
@@ -2046,7 +2114,7 @@ class ProxyFactoryTests(unittest.TestCase):
         self.shouldFail(doit2)
 
     @_skip_if_not_Py2
-    def test_coerce(self):
+    def test_coerce(self):  # pragma: no cover
         from zope.security.proxy import removeSecurityProxy
         P = self.c.proxy
 
@@ -2203,8 +2271,8 @@ class LocationProxySecurityCheckerTests(unittest.TestCase):
         import zope.security
         try:
             from importlib import reload as _reload
-        except ImportError:
-            _reload = reload # Python 2
+        except ImportError:  # pragma: PY2
+            _reload = reload  # noqa: F821 undefined name 'reload'
 
         # This attribute is set when zope.security.decorator is imported, to
         # show that it will be set too, if zope.security.proxy is imported
diff --git a/src/zope/security/tests/test_simplepolicies.py b/src/zope/security/tests/test_simplepolicies.py
index ce5c483..fcbc8de 100644
--- a/src/zope/security/tests/test_simplepolicies.py
+++ b/src/zope/security/tests/test_simplepolicies.py
@@ -35,7 +35,7 @@ class ConformsToIInteraction(object):
 
 class ParanoidSecurityPolicyTests(unittest.TestCase,
                                   ConformsToIInteraction,
-                                 ):
+                                  ):
 
     def _getTargetClass(self):
         from zope.security.simplepolicies import ParanoidSecurityPolicy
@@ -87,6 +87,7 @@ class ParanoidSecurityPolicyTests(unittest.TestCase,
 
     def test_checkPermission_w_non_public_only_system_user(self):
         from zope.security._definitions import system_user
+
         class Participation(object):
             interaction = None
             principal = system_user
@@ -111,6 +112,7 @@ class ParanoidSecurityPolicyTests(unittest.TestCase,
         self.assertTrue(policy.checkPermission(None, None))
         self.assertTrue(policy.checkPermission(self, self))
 
+
 class PermissiveSecurityPolicyTests(unittest.TestCase,
                                     ConformsToIInteraction):
 
diff --git a/src/zope/security/tests/test_testing.py b/src/zope/security/tests/test_testing.py
index 42eebd0..cc11037 100644
--- a/src/zope/security/tests/test_testing.py
+++ b/src/zope/security/tests/test_testing.py
@@ -18,6 +18,7 @@ from zope.testing.cleanup import CleanUp
 from zope.security import testing
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 class TestTestingFunctions(CleanUp,
                            unittest.TestCase):
 
@@ -50,6 +51,7 @@ class TestTestingFunctions(CleanUp,
 
     def test_contextmanager_ends_interaction_on_exception(self):
         from zope.security.management import queryInteraction
+
         class MyError(Exception):
             pass
 
@@ -59,7 +61,6 @@ class TestTestingFunctions(CleanUp,
 
         self.assertFalse(queryInteraction())
 
-
     def test_addCheckerPublic(self):
         from zope import component
         from zope.security.interfaces import IPermission
@@ -69,7 +70,5 @@ class TestTestingFunctions(CleanUp,
         self.assertIs(perm, utility)
 
 
-
-
 def test_suite():
     return unittest.defaultTestLoader.loadTestsFromName(__name__)
diff --git a/src/zope/security/tests/test_zcml.py b/src/zope/security/tests/test_zcml.py
index 9fb1cc4..2cdf62a 100644
--- a/src/zope/security/tests/test_zcml.py
+++ b/src/zope/security/tests/test_zcml.py
@@ -14,6 +14,7 @@
 import unittest
 from zope.security.interfaces import PUBLIC_PERMISSION_NAME as zope_Public
 
+
 class ConformsToIFromUnicode(object):
 
     def test_class_conforms_to_IFromUnicode(self):
@@ -29,7 +30,7 @@ class ConformsToIFromUnicode(object):
 
 class PermissionTests(unittest.TestCase,
                       ConformsToIFromUnicode,
-                     ):
+                      ):
 
     def _getTargetClass(self):
         from zope.security.zcml import Permission
@@ -147,38 +148,38 @@ class Test_redefinePermission(unittest.TestCase):
 
     def test_wo_existing_mapping(self):
         z_context = DummyZCMLContext()
+
         class Context(object):
             pass
         context = z_context.context = Context()
         after = object()
         self._callFUT(z_context, 'before.permission', after)
-        self.assertTrue(context.permission_mapping['before.permission']
-                            is after)
+        self.assertIs(context.permission_mapping['before.permission'], after)
 
     def test_w_existing_mapping_wo_existing_key(self):
         z_context = DummyZCMLContext()
+
         class Context(object):
             pass
         context = z_context.context = Context()
         mapping = context.permission_mapping = {}
         after = object()
         self._callFUT(z_context, 'before.permission', after)
-        self.assertTrue(context.permission_mapping is mapping)
-        self.assertTrue(context.permission_mapping['before.permission']
-                            is after)
+        self.assertIs(context.permission_mapping, mapping)
+        self.assertIs(context.permission_mapping['before.permission'], after)
 
     def test_w_existing_mapping_w_existing_key(self):
         z_context = DummyZCMLContext()
+
         class Context(object):
             pass
         context = z_context.context = Context()
         mapping = context.permission_mapping = {}
-        before = mapping['before.permission'] = object()
+        mapping['before.permission'] = object()
         after = object()
         self._callFUT(z_context, 'before.permission', after)
-        self.assertTrue(context.permission_mapping is mapping)
-        self.assertTrue(context.permission_mapping['before.permission']
-                            is after)
+        self.assertIs(context.permission_mapping, mapping)
+        self.assertIs(context.permission_mapping['before.permission'], after)
 
 
 class DummyZCMLContext(object):
diff --git a/src/zope/security/tests/test_zcml_functest.py b/src/zope/security/tests/test_zcml_functest.py
index b669847..2486af6 100644
--- a/src/zope/security/tests/test_zcml_functest.py
+++ b/src/zope/security/tests/test_zcml_functest.py
@@ -52,7 +52,6 @@ class TestClassDirective(unittest.TestCase):
         import zope.security
         XMLConfig('meta.zcml', zope.security)()
 
-
     def testEmptyDirective(self):
         from zope.configuration.xmlconfig import xmlconfig
         self._meta()
@@ -62,7 +61,6 @@ class TestClassDirective(unittest.TestCase):
                        """)
         xmlconfig(f)
 
-
     def testImplements(self):
         from zope.component.interface import queryInterface
         from zope.configuration.xmlconfig import xmlconfig
@@ -83,7 +81,6 @@ class TestClassDirective(unittest.TestCase):
         self.assertEqual(queryInterface(
             "zope.security.tests.exampleclass.IExample"), IExample)
 
-
     def testMulImplements(self):
         from zope.component.interface import queryInterface
         from zope.configuration.xmlconfig import xmlconfig
@@ -112,7 +109,7 @@ class TestClassDirective(unittest.TestCase):
             "zope.security.tests.exampleclass.IExample"), IExample)
         self.assertEqual(queryInterface(
             "zope.security.tests.exampleclass.IExample2"),
-                         IExample2)
+            IExample2)
 
     def testRequire(self):
         from zope.configuration.xmlconfig import xmlconfig
@@ -162,7 +159,6 @@ class TestFactorySubdirective(unittest.TestCase):
         import zope.security
         XMLConfig('meta.zcml', zope.security)()
 
-
     def testFactory(self):
         from zope.component import getUtility
         from zope.component.interfaces import IFactory
@@ -208,7 +204,6 @@ class TestFactorySubdirective(unittest.TestCase):
         self.assertEqual(factory.title, "Example content")
         self.assertEqual(factory.description, "Example description")
 
-
     def testFactoryPublicPermission(self):
         from zope.component import getUtility
         from zope.component.interfaces import IFactory
@@ -251,7 +246,6 @@ class TestFactoryDirective(unittest.TestCase):
         from zope.configuration.xmlconfig import XMLConfig
         XMLConfig('meta.zcml', zope.security)()
 
-
     def testFactory(self):
         from zope.component import createObject
         from zope.configuration.xmlconfig import xmlconfig
@@ -272,11 +266,11 @@ class TestFactoryDirective(unittest.TestCase):
         self.assertTrue(proxy.isinstance(obj, exampleclass.ExampleClass))
 
 
-
 def _pfx(name):
     from zope.security.tests import module
     return module.__name__ + '.' + name
 
+
 def defineDirectives():
     from zope.configuration.xmlconfig import XMLConfig
     from zope.configuration.xmlconfig import xmlconfig
@@ -289,11 +283,13 @@ def defineDirectives():
        <permission id="zope.Paltry" title="paltry" />
     </configure>"""))
 
+
 NOTSET = ()
 
 P1 = "zope.Extravagant"
 P2 = "zope.Paltry"
 
+
 class TestRequireDirective(unittest.TestCase):
 
     def setUp(self):
@@ -306,6 +302,7 @@ class TestRequireDirective(unittest.TestCase):
         class B(object):
             def m1(self):
                 raise AssertionError("Never called")
+
             def m2(self):
                 raise AssertionError("Never called")
 
@@ -313,6 +310,7 @@ class TestRequireDirective(unittest.TestCase):
         class C(B):
             def m3(self):
                 raise AssertionError("Never called")
+
             def m4(self):
                 raise AssertionError("Never called")
 
@@ -328,7 +326,7 @@ class TestRequireDirective(unittest.TestCase):
         tearDown()
 
     def assertState(self, m1P=NOTSET, m2P=NOTSET, m3P=NOTSET):
-        #Verify that class, instance, and methods have expected permissions
+        # Verify that class, instance, and methods have expected permissions
         from zope.security.checker import selectChecker
         from zope.security.tests import module
         checker = selectChecker(module.test_instance)
@@ -399,7 +397,6 @@ class TestRequireDirective(unittest.TestCase):
 
         self.assertEqual(queryInterface(_pfx("S")), module.S)
 
-
         checker = selectChecker(module.test_instance)
         self.assertEqual(checker.setattr_permission_id('m1'), None)
         self.assertEqual(checker.setattr_permission_id('m2'), None)
@@ -426,7 +423,6 @@ class TestRequireDirective(unittest.TestCase):
         self.assertEqual(queryInterface(_pfx("S")), module.S)
         self.assertEqual(queryInterface(_pfx("S2")), module.S2)
 
-
         checker = selectChecker(module.test_instance)
         self.assertEqual(checker.setattr_permission_id('m1'), None)
         self.assertEqual(checker.setattr_permission_id('m2'), None)
@@ -454,7 +450,6 @@ class TestRequireDirective(unittest.TestCase):
         # Make sure we know about the interfaces
         self.assertEqual(queryInterface(_pfx("I")), module.I)
 
-
     def testMultipleInterface(self):
         from zope.component.interface import queryInterface
         from zope.security.tests import module
@@ -478,7 +473,6 @@ class TestRequireDirective(unittest.TestCase):
     # "testComposite*TopPerm" exercises tags with permission in containing tag.
     # "testComposite*ElementPerm" exercises tags w/permission in children.
 
-
     def testCompositeNoPerm(self):
         # Establish rejection of declarations lacking a permission spec.
         from zope.configuration.exceptions import ConfigurationError
@@ -490,7 +484,6 @@ class TestRequireDirective(unittest.TestCase):
         with self.assertRaises(ConfigurationError):
             self.assertDeclaration(declaration)
 
-
     def testCompositeMethodsPluralElementPerm(self):
         declaration = ('''<class class="%s">
                             <require
@@ -501,7 +494,6 @@ class TestRequireDirective(unittest.TestCase):
         self.assertDeclaration(declaration,
                                m1P=P1, m3P=P1)
 
-
     def testCompositeInterfaceTopPerm(self):
         declaration = ('''<class class="%s">
                             <require
@@ -512,7 +504,6 @@ class TestRequireDirective(unittest.TestCase):
         self.assertDeclaration(declaration,
                                m1P=P1, m2P=P1)
 
-
     def testSubInterfaces(self):
         declaration = ('''<class class="%s">
                             <require
@@ -523,7 +514,6 @@ class TestRequireDirective(unittest.TestCase):
         # m1 and m2 are in the interface, so should be set, and m3 should not:
         self.assertDeclaration(declaration, m1P=P1, m2P=P1)
 
-
     def testMimicOnly(self):
         declaration = ('''<class class="%s">
                             <require
@@ -534,12 +524,11 @@ class TestRequireDirective(unittest.TestCase):
                             <require like_class="%s" />
                           </class>
                           ''' % (_pfx("test_base"), P1,
-                _pfx("test_class"), _pfx("test_base")))
+                                 _pfx("test_class"), _pfx("test_base")))
         # m1 and m2 are in the interface, so should be set, and m3 should not:
         self.assertDeclaration(declaration,
                                m1P=P1, m2P=P1)
 
-
     def testMimicAsDefault(self):
         declaration = ('''<class class="%s">
                             <require
@@ -553,7 +542,7 @@ class TestRequireDirective(unittest.TestCase):
                                 attributes="m2 m3"/>
                           </class>
                           ''' % (_pfx("test_base"), P1,
-                _pfx("test_class"), _pfx("test_base"), P2))
+                                 _pfx("test_class"), _pfx("test_base"), P2))
 
         # m1 and m2 are in the interface, so should be set, and m3 should not:
         self.assertDeclaration(declaration,
@@ -564,21 +553,22 @@ def apply_declaration(declaration):
     '''Apply the xmlconfig machinery.'''
     from zope.configuration.xmlconfig import xmlconfig
     if isinstance(declaration, bytes):
-        declaration = declaration.decode("utf-8")
+        declaration = declaration.decode("utf-8")  # pragma: no cover PY2
     return xmlconfig(io.StringIO(declaration))
 
 
-
 def make_dummy():
     from zope.interface import Interface
     import zope.security.zcml
     global IDummy
+
     class IDummy(Interface):
         perm = zope.security.zcml.Permission(title=u'')
 
 
 perms = []
 
+
 def dummy(context_, perm):
     global perms
     perms.append(perm)
diff --git a/src/zope/security/zcml.py b/src/zope/security/zcml.py
index 473c06e..4e3c17c 100644
--- a/src/zope/security/zcml.py
+++ b/src/zope/security/zcml.py
@@ -65,6 +65,7 @@ class ISecurityPolicyDirective(Interface):
         description=u"Pointer to the object that will handle the security.",
         required=True)
 
+
 def securityPolicy(_context, component):
     _context.action(
         discriminator='defaultPolicy',
@@ -72,6 +73,7 @@ def securityPolicy(_context, component):
         args=(component,)
     )
 
+
 class IPermissionDirective(Interface):
     """Define a new security object."""
 
@@ -90,6 +92,7 @@ class IPermissionDirective(Interface):
         description=u"Provides a description for the object.",
         required=False)
 
+
 def permission(_context, id, title, description=u''):
     from zope.security.interfaces import IPermission
     from zope.security.permission import Permission
@@ -97,6 +100,7 @@ def permission(_context, id, title, description=u''):
     permission = Permission(id, title, description)
     utility(_context, IPermission, permission, name=id)
 
+
 class IRedefinePermission(Interface):
     """Define a permission to replace another permission."""
 
@@ -110,6 +114,7 @@ class IRedefinePermission(Interface):
         description=u"Substituted permission ID.",
         required=True)
 
+
 def redefinePermission(_context, from_, to):
     _context = _context.context