Config with pure python template (#19)

* Drop support for Python 2.7, 3.5, 3.6.
* Add support for Python 3.11.

30 files changed, 267 insertions, 543 deletions

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 927d9f3..2ca497a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -17,32 +17,30 @@ jobs:
       fail-fast: false
       matrix:
         os:
-        - ubuntu
+        - ["ubuntu", "ubuntu-20.04"]
         config:
         # [Python version, tox env]
         - ["3.9",   "lint"]
-        - ["2.7",   "py27"]
-        - ["3.5",   "py35"]
-        - ["3.6",   "py36"]
         - ["3.7",   "py37"]
         - ["3.8",   "py38"]
         - ["3.9",   "py39"]
         - ["3.10",  "py310"]
-        - ["pypy-2.7", "pypy"]
+        - ["3.11",  "py311"]
         - ["pypy-3.7", "pypy3"]
         - ["3.9",   "docs"]
         - ["3.9",   "coverage"]
 
-    runs-on: ${{ matrix.os }}-latest
+    runs-on: ${{ matrix.os[1] }}
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
     name: ${{ matrix.config[1] }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.config[0] }}
     - name: Pip cache
-      uses: actions/cache@v2
+      uses: actions/cache@v3
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ matrix.config[0] }}-${{ hashFiles('setup.*', 'tox.ini') }}
@@ -58,7 +56,7 @@ jobs:
     - name: Coverage
       if: matrix.config[1] == 'coverage'
       run: |
-        pip install coveralls coverage-python-version
+        pip install coveralls
         coveralls --service=github
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/.gitignore b/.gitignore
index c724a76..1f321f5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,4 +28,5 @@ lib64
 log/
 parts/
 pyvenv.cfg
+testing.log
 var/
diff --git a/.meta.toml b/.meta.toml
index 0a00784..9c7cd6c 100644
--- a/.meta.toml
+++ b/.meta.toml
@@ -2,29 +2,21 @@
 # https://github.com/zopefoundation/meta/tree/master/config/pure-python
 [meta]
 template = "pure-python"
-commit-id = "3b712f305ca8207e971c5bf81f2bdb5872489f2f"
+commit-id = "d03ad585"
 
 [python]
 with-pypy = true
-with-legacy-python = true
 with-docs = true
 with-sphinx-doctests = false
 with-windows = false
 with-future-python = false
+with-macos = false
 
 [tox]
 use-flake8 = true
 
 [coverage]
-fail-under = 81
-
-[flake8]
-additional-config = [
-    "# E741 ambiguous variable name",
-    "# F821 undefined name",
-    "per-file-ignores =",
-    "    src/zope/tal/talgettext.py: E741 F821",
-    ]
+fail-under = 84
 
 [manifest]
 additional-rules = [
diff --git a/CHANGES.rst b/CHANGES.rst
index c5f118d..2b44681 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -2,14 +2,23 @@
  Changes
 =========
 
-4.6 (unreleased)
+5.0 (unreleased)
 ================
 
+- Add support for Python 3.11.
+
+- Drop support for Python 2.7, 3.5, 3.6.
+
 - Add support for Python 3.10.
 
 - Add ``nav`` to the list of HTML block level elements.
   (`#18 <https://github.com/zopefoundation/zope.tal/pull/18>`_)
 
+- Remove ``.talgettext.UpdatePOEngine`` and the ability to call
+  ``zope/tal/talgettext.py`` (main function). The code was broken and unused.
+
+- Remove support to run the tests using deprecated ``python setup.py test``.
+
 
 4.5 (2021-05-28)
 ================
diff --git a/setup.cfg b/setup.cfg
index f32b31d..ebb8516 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,17 +1,24 @@
 # Generated from:
 # https://github.com/zopefoundation/meta/tree/master/config/pure-python
 [bdist_wheel]
-universal = 1
+universal = 0
 
 [flake8]
 doctests = 1
-# E741 ambiguous variable name
-# F821 undefined name
-per-file-ignores =
-    src/zope/tal/talgettext.py: E741 F821
 
 [check-manifest]
 ignore =
     .editorconfig
     .meta.toml
     docs/_build/html/_sources/*
+
+[isort]
+force_single_line = True
+combine_as_imports = True
+sections = FUTURE,STDLIB,THIRDPARTY,ZOPE,FIRSTPARTY,LOCALFOLDER
+known_third_party = six, docutils, pkg_resources
+known_zope =
+known_first_party =
+default_section = ZOPE
+line_length = 79
+lines_after_imports = 2
diff --git a/setup.py b/setup.py
index c4cf96f..7441d23 100644
--- a/setup.py
+++ b/setup.py
@@ -19,8 +19,10 @@
 """Setup for zope.tal package
 """
 import os
-import sys
-from setuptools import setup, find_packages
+
+from setuptools import find_packages
+from setuptools import setup
+
 
 here = os.path.dirname(__file__)
 
@@ -30,28 +32,13 @@ def read(*rnames):
         return f.read()
 
 
-def alltests():
-    # use the zope.testrunner machinery to find all the
-    # test suites we've put under ourselves
-    from zope.testrunner.options import get_options
-    from zope.testrunner.find import find_suites
-    from unittest import TestSuite
-    here = os.path.abspath(os.path.dirname(sys.argv[0]))
-    args = sys.argv[:]
-    src = os.path.join(here, 'src')
-    defaults = ['--test-path', src]
-    options = get_options(args, defaults)
-    suites = list(find_suites(options))
-    return TestSuite(suites)
-
-
 TESTS_REQUIRE = [
     'zope.testing',
     'zope.testrunner',
 ]
 
 setup(name='zope.tal',
-      version='4.6.dev0',
+      version='5.0.dev0',
       author='Zope Foundation and Contributors',
       author_email='zope-dev@zope.org',
       description='Zope Template Application Language (TAL)',
@@ -67,15 +54,12 @@ setup(name='zope.tal',
           'Intended Audience :: Developers',
           'License :: OSI Approved :: Zope Public License',
           'Programming Language :: Python',
-          'Programming Language :: Python :: 2',
-          'Programming Language :: Python :: 2.7',
           'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.5',
-          'Programming Language :: Python :: 3.6',
           'Programming Language :: Python :: 3.7',
           'Programming Language :: Python :: 3.8',
           'Programming Language :: Python :: 3.9',
           'Programming Language :: Python :: 3.10',
+          'Programming Language :: Python :: 3.11',
           'Programming Language :: Python :: Implementation :: CPython',
           'Programming Language :: Python :: Implementation :: PyPy',
           'Natural Language :: English',
@@ -95,8 +79,6 @@ setup(name='zope.tal',
               'repoze.sphinx.autointerface',
           ],
       },
-      test_suite="__main__.alltests",  # to support "setup.py test"
-      tests_require=TESTS_REQUIRE,
       install_requires=[
           'setuptools',
           'zope.i18nmessageid',
diff --git a/src/zope/tal/driver.py b/src/zope/tal/driver.py
index c64c602..2abadea 100644
--- a/src/zope/tal/driver.py
+++ b/src/zope/tal/driver.py
@@ -16,10 +16,9 @@
 interprets a file, prints results to stdout.
 """
 
-from __future__ import print_function
 
-import os
 import optparse
+import os
 import sys
 
 # Import local classes
diff --git a/src/zope/tal/dummyengine.py b/src/zope/tal/dummyengine.py
index cfc71ea..237ea84 100644
--- a/src/zope/tal/dummyengine.py
+++ b/src/zope/tal/dummyengine.py
@@ -14,24 +14,16 @@
 """Dummy TAL expression engine so that I can test out the TAL implementation.
 """
 import re
+from io import StringIO
 
-try:
-    # Python 2.x
-    from StringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
-
-from zope.interface import implementer
-from zope.tal.taldefs import NAME_RE, TALExpressionError, ErrorInfo
-from zope.tal.interfaces import ITALExpressionCompiler, ITALExpressionEngine
 from zope.i18nmessageid import Message
+from zope.interface import implementer
 
-
-try:
-    unicode
-except NameError:
-    unicode = str  # Python 3.x
+from zope.tal.interfaces import ITALExpressionCompiler
+from zope.tal.interfaces import ITALExpressionEngine
+from zope.tal.taldefs import NAME_RE
+from zope.tal.taldefs import ErrorInfo
+from zope.tal.taldefs import TALExpressionError
 
 
 Default = object()
@@ -44,7 +36,7 @@ class CompilerError(Exception):
 
 
 @implementer(ITALExpressionCompiler, ITALExpressionEngine)
-class DummyEngine(object):
+class DummyEngine:
 
     position = None
     source_file = None
@@ -128,7 +120,7 @@ class DummyEngine(object):
                 lineno, offset = self.position
             else:
                 lineno, offset = None, None
-            return '%s (%s,%s)' % (self.source_file, lineno, offset)
+            return '{} ({},{})'.format(self.source_file, lineno, offset)
         raise TALExpressionError(
             "unrecognized expression: " +
             repr(expression))
@@ -151,7 +143,7 @@ class DummyEngine(object):
 
     def evaluateText(self, expr):
         text = self.evaluate(expr)
-        if isinstance(text, (str, unicode, Message)):
+        if isinstance(text, (str, Message)):
             return text
         if text is not None and text is not Default:
             text = str(text)
@@ -256,7 +248,7 @@ class DummyEngine(object):
         return result.getvalue()
 
 
-class Iterator(object):
+class Iterator:
 
     def __init__(self, name, seq, engine):
         self.name = name
@@ -273,10 +265,9 @@ class Iterator(object):
         self.nextIndex = i + 1
         self.engine.setLocal(self.name, item)
         return 1
-    next = __next__  # Python 2 compatibility
 
 
-class DummyTranslationDomain(object):
+class DummyTranslationDomain:
 
     domain = ''
 
@@ -327,7 +318,7 @@ class DummyTranslationDomain(object):
         self.appendMsgid(domain, (msgid, mapping))
 
         def repl(m):
-            return unicode(mapping[m.group(m.lastindex).lower()])
+            return str(mapping[m.group(m.lastindex).lower()])
         cre = re.compile(r'\$(?:([_A-Za-z][-\w]*)|\{([_A-Za-z][-\w]*)\})')
         return cre.sub(repl, text)
 
diff --git a/src/zope/tal/htmltalparser.py b/src/zope/tal/htmltalparser.py
index 2c65acd..0920072 100644
--- a/src/zope/tal/htmltalparser.py
+++ b/src/zope/tal/htmltalparser.py
@@ -15,40 +15,37 @@
 Parse HTML and compile to :class:`~.TALInterpreter` intermediate code, using
 a :class:`~.TALGenerator`.
 """
-
-# When Python 3 becomes mainstream please swap the try and except parts.
-try:
-    # Python 2.x
-    from HTMLParser import HTMLParser, HTMLParseError
-except ImportError:
-    # Python 3.x
-    from html.parser import HTMLParser
-    try:
-        from html.parser import HTMLParseError
-    except ImportError:
-        # Python 3.5 removed it, but we need it as a base class
-        # so here's a copy taken from Python 3.4:
-        class HTMLParseError(Exception):
-            def __init__(self, msg, position=(None, None)):
-                Exception.__init__(self)
-                assert msg
-                self.msg = msg
-                self.lineno = position[0]
-                self.offset = position[1]
-
-            def __str__(self):
-                result = self.msg
-                if self.lineno is not None:
-                    result = result + ", at line %d" % self.lineno
-                if self.offset is not None:
-                    result = result + ", column %d" % (self.offset + 1)
-                return result
-
-from zope.tal.taldefs import (ZOPE_METAL_NS, ZOPE_TAL_NS, ZOPE_I18N_NS,
-                              METALError, TALError, I18NError)
+from html.parser import HTMLParser
+
+from zope.tal.taldefs import ZOPE_I18N_NS
+from zope.tal.taldefs import ZOPE_METAL_NS
+from zope.tal.taldefs import ZOPE_TAL_NS
+from zope.tal.taldefs import I18NError
+from zope.tal.taldefs import METALError
+from zope.tal.taldefs import TALError
 from zope.tal.talgenerator import TALGenerator
 
 
+class HTMLParseError(Exception):
+    # Python 3.5 removed this class, but we need it as a base class
+    # so here's a copy taken from Python 3.4
+
+    def __init__(self, msg, position=(None, None)):
+        Exception.__init__(self)
+        assert msg
+        self.msg = msg
+        self.lineno = position[0]
+        self.offset = position[1]
+
+    def __str__(self):
+        result = self.msg
+        if self.lineno is not None:
+            result = result + ", at line %d" % self.lineno
+        if self.offset is not None:
+            result = result + ", column %d" % (self.offset + 1)
+        return result
+
+
 _html_parser_extras = {}
 if 'convert_charrefs' in HTMLParser.__init__.__code__.co_names:
     _html_parser_extras['convert_charrefs'] = False  # pragma: NO COVER py34
@@ -129,7 +126,7 @@ class OpenTagError(NestingError):
 
     def __init__(self, tagstack, tag, position=(None, None)):
         self.tag = tag
-        msg = 'Tag <%s> is not allowed in <%s>' % (tag, tagstack[-1])
+        msg = 'Tag <{}> is not allowed in <{}>'.format(tag, tagstack[-1])
         HTMLParseError.__init__(self, msg, position)
 
 
diff --git a/src/zope/tal/interfaces.py b/src/zope/tal/interfaces.py
index bd6286a..311bc76 100644
--- a/src/zope/tal/interfaces.py
+++ b/src/zope/tal/interfaces.py
@@ -22,7 +22,8 @@ most commonly used are :class:`zope.tales.tales.ExpressionEngine`,
 :class:`zope.tales.tales.Context`, and
 :class:`zope.tales.tales.Iterator`, respectively.
 """
-from zope.interface import Attribute, Interface
+from zope.interface import Attribute
+from zope.interface import Interface
 
 
 class ITALExpressionCompiler(Interface):
diff --git a/src/zope/tal/runtest.py b/src/zope/tal/runtest.py
index df9d1c7..57feef9 100644
--- a/src/zope/tal/runtest.py
+++ b/src/zope/tal/runtest.py
@@ -17,22 +17,15 @@ compares interpeted test files with expected output files in a sibling
 directory.
 """
 
-from __future__ import print_function
 
+import copy
+import difflib
 import glob
+import optparse
 import os
 import sys
 import traceback
-import difflib
-import copy
-import optparse
-
-try:
-    # Python 2.x
-    from cStringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
+from io import StringIO
 
 import zope.tal.driver
 import zope.tal.tests.utils
@@ -121,7 +114,7 @@ def main(argv=None, out=sys.stdout):
             tail)
         try:
             f = open(outfile)
-        except IOError:
+        except OSError:
             expected = None
             print("(missing file %s)" % outfile, end=' ', file=out)
         else:
@@ -135,7 +128,7 @@ def main(argv=None, out=sys.stdout):
         if opts.normalize_newlines or "_sa" in arg or arg.endswith('.xml'):
             # EOL normalization makes the tests pass:
             # - XML files, on Windows, have \r\n line endings.  Because
-            #   expat insists on byte streams on Python 3, we end up with
+            #   expat insists on byte streams, we end up with
             #   those \r\n's going through the entire TAL engine and
             #   showing up in the actual output.  Expected output, on the
             #   other hand, has just \n's, since we read the file as text.
diff --git a/src/zope/tal/taldefs.py b/src/zope/tal/taldefs.py
index 61d20d1..1a7331d 100644
--- a/src/zope/tal/taldefs.py
+++ b/src/zope/tal/taldefs.py
@@ -14,9 +14,12 @@
 """Common definitions used by TAL and METAL compilation and transformation.
 """
 import re
-from zope.tal.interfaces import ITALExpressionErrorInfo
+
 from zope.interface import implementer
 
+from zope.tal.interfaces import ITALExpressionErrorInfo
+
+
 #: Version of the specification we implement.
 TAL_VERSION = "1.6"
 
@@ -114,7 +117,7 @@ class I18NError(TALError):
 
 
 @implementer(ITALExpressionErrorInfo)
-class ErrorInfo(object):
+class ErrorInfo:
     """
     Default implementation of
     :class:`zope.tal.interfaces.ITALExpressionErrorInfo`.
diff --git a/src/zope/tal/talgenerator.py b/src/zope/tal/talgenerator.py
index a7adf3d..03e0a77 100644
--- a/src/zope/tal/talgenerator.py
+++ b/src/zope/tal/talgenerator.py
@@ -15,30 +15,23 @@
 Code generator for :class:`~.TALInterpreter` intermediate code.
 """
 import re
-
-try:
-    # Python 3.x
-    from html import escape
-except ImportError:
-    # Python 2.x
-    from cgi import escape
+from html import escape
 
 from zope.tal import taldefs
-from zope.tal.taldefs import NAME_RE, TAL_VERSION
-from zope.tal.taldefs import I18NError, METALError, TALError
+from zope.tal.taldefs import NAME_RE
+from zope.tal.taldefs import TAL_VERSION
+from zope.tal.taldefs import I18NError
+from zope.tal.taldefs import METALError
+from zope.tal.taldefs import TALError
 from zope.tal.taldefs import parseSubstitution
-from zope.tal.translationcontext import TranslationContext, DEFAULT_DOMAIN
-
-try:
-    xrange
-except NameError:
-    xrange = range  # Python 3.x
+from zope.tal.translationcontext import DEFAULT_DOMAIN
+from zope.tal.translationcontext import TranslationContext
 
 
 _name_rx = re.compile(NAME_RE)
 
 
-class TALGenerator(object):
+class TALGenerator:
     """
     Generate intermediate code.
     """
@@ -90,7 +83,7 @@ class TALGenerator(object):
         output = []
         collect = []
         cursor = 0
-        for cursor in xrange(len(program) + 1):
+        for cursor in range(len(program) + 1):
             try:
                 item = program[cursor]
             except IndexError:
@@ -163,7 +156,7 @@ class TALGenerator(object):
     def optimizeStartTag(self, collect, name, attrlist, end):
         # return true if the tag can be converted to plain text
         if not attrlist:
-            collect.append("<%s%s" % (name, end))
+            collect.append("<{}{}".format(name, end))
             return 1
         opt = 1
         new = ["<" + name]
@@ -177,7 +170,7 @@ class TALGenerator(object):
                 if item[1] is None:
                     s = item[0]
                 else:
-                    s = '%s="%s"' % (item[0], taldefs.attrEscape(item[1]))
+                    s = '{}="{}"'.format(item[0], taldefs.attrEscape(item[1]))
                 attrlist[i] = item[0], s
                 new.append(" " + s)
         # if no non-optimizable attributes were found, convert to plain text
@@ -219,8 +212,11 @@ class TALGenerator(object):
         try:
             return self.expressionCompiler.compile(expr)
         except self.CompilerError as err:
-            raise TALError('%s in expression %s' % (err.args[0], repr(expr)),
-                           self.position)
+            raise TALError(
+                '{} in expression {}'.format(
+                    err.args[0],
+                    repr(expr)),
+                self.position)
 
     def pushProgram(self):
         self.stack.append(self.program)
diff --git a/src/zope/tal/talgettext.py b/src/zope/tal/talgettext.py
index bc90439..08f621b 100644
--- a/src/zope/tal/talgettext.py
+++ b/src/zope/tal/talgettext.py
@@ -12,44 +12,22 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
-"""Program to extract internationalization markup from Page Templates.
+"""Extract internationalization markup from Page Templates.
 
 Once you have marked up a Page Template file with i18n: namespace tags, use
-this program to extract GNU gettext .po file entries.
-
-Usage: talgettext.py [options] files
-Options:
-    -h / --help
-        Print this message and exit.
-    -o / --output <file>
-        Output the translation .po file to <file>.
-    -u / --update <file>
-        Update the existing translation <file> with any new translation strings
-        found.
+this code to extract GNU gettext .po file entries.
 """
 
-# XXX this module seems to be unused, it has NameErrors and is not Python 3
-#     compatible.
-
-from __future__ import print_function
-
-import sys
-import time
-import getopt
-import traceback
 import warnings
 
+from zope.i18nmessageid import Message
 from zope.interface import implementer
-from zope.tal.htmltalparser import HTMLTALParser
-from zope.tal.talinterpreter import TALInterpreter, normalize
+
 from zope.tal.dummyengine import DummyEngine
 from zope.tal.interfaces import ITALExpressionEngine
-from zope.tal.taldefs import TALExpressionError
-from zope.i18nmessageid import Message
+from zope.tal.talinterpreter import TALInterpreter
+from zope.tal.talinterpreter import normalize
 
-PY3 = sys.version_info > (3,)
-if PY3:
-    unicode = str
 
 pot_header = '''\
 # SOME DESCRIPTIVE TITLE.
@@ -72,18 +50,10 @@ msgstr ""
 NLSTR = '"\n"'
 
 
-def usage(code, msg=''):
-    # Python 2.1 required
-    print(__doc__, file=sys.stderr)
-    if msg:
-        print(msg, file=sys.stderr)
-    sys.exit(code)
-
-
 class POTALInterpreter(TALInterpreter):
     def translate(self, msgid, default=None, i18ndict=None, obj=None):
         if default is None:
-            default = getattr(msgid, 'default', unicode(msgid))
+            default = getattr(msgid, 'default', str(msgid))
         # If no i18n dict exists yet, create one.
         if i18ndict is None:
             i18ndict = {}
@@ -145,200 +115,16 @@ class POEngine(DummyEngine):
                 references = '\n'.join([location[0] + ':' + str(location[1])
                                         for location in domain[msgid]])
                 # Note: a lot of encode calls here are needed so
-                # Python 3 does not break.
+                # it does not break.
                 warnings.warn(
                     "Warning: msgid '%s' in %s already exists "
                     "with a different default (bad: %s, should be: %s)\n"
                     "The references for the existent value are:\n%s\n" %
                     (msgid.encode('utf-8'),
-                     self.file.encode('utf-8') + ':'.encode('utf-8')
+                     self.file.encode('utf-8') + b':'
                      + str(position).encode('utf-8'),
                      msgid.default.encode('utf-8'),
                      existing_msgid.default.encode('utf-8'),
                      references.encode('utf-8')))
         domain[msgid].append((self.file, position))
         return 'x'
-
-
-class UpdatePOEngine(POEngine):
-    """A slightly-less braindead POEngine which supports loading an existing
-    .po file first."""
-
-    def __init__(self, macros=None, filename=None):
-        POEngine.__init__(self, macros)
-
-        self._filename = filename
-        self._loadFile()
-        self.base = self.catalog
-        self.catalog = {}
-
-    def __add(self, id, s, fuzzy):
-        "Add a non-fuzzy translation to the dictionary."
-        if not fuzzy and str:
-            # check for multi-line values and munge them appropriately
-            if '\n' in s:
-                lines = s.rstrip().split('\n')
-                s = NLSTR.join(lines)
-            self.catalog[id] = s
-
-    def _loadFile(self):
-        # shamelessly cribbed from Python's Tools/i18n/msgfmt.py
-        # 25-Mar-2003 Nathan R. Yergler (nathan@zope.org)
-        # 14-Apr-2003 Hacked by Barry Warsaw (barry@zope.com)
-
-        ID = 1
-        STR = 2
-
-        try:
-            lines = open(self._filename).readlines()
-        except IOError as msg:
-            print(msg, file=sys.stderr)
-            sys.exit(1)
-
-        section = None
-        fuzzy = False
-
-        # Parse the catalog
-        lno = 0
-        for l in lines:
-            lno += True
-            # If we get a comment line after a msgstr, this is a new entry
-            if l[0] == '#' and section == STR:
-                self.__add(msgid, msgstr, fuzzy)
-                section = None
-                fuzzy = False
-            # Record a fuzzy mark
-            if l[:2] == '#,' and l.find('fuzzy'):
-                fuzzy = True
-            # Skip comments
-            if l[0] == '#':
-                continue
-            # Now we are in a msgid section, output previous section
-            if l.startswith('msgid'):
-                if section == STR:
-                    self.__add(msgid, msgstr, fuzzy)
-                section = ID
-                l = l[5:]
-                msgid = msgstr = ''
-            # Now we are in a msgstr section
-            elif l.startswith('msgstr'):
-                section = STR
-                l = l[6:]
-            # Skip empty lines
-            if not l.strip():
-                continue
-            # TODO: Does this always follow Python escape semantics?
-            l = eval(l)
-            if section == ID:
-                msgid += l
-            elif section == STR:
-                msgstr += '%s\n' % l
-            else:
-                print('Syntax error on %s:%d' % (infile, lno),
-                      'before:', file=sys.stderr)
-                print(l, file=sys.stderr)
-                sys.exit(1)
-        # Add last entry
-        if section == STR:
-            self.__add(msgid, msgstr, fuzzy)
-
-    def evaluate(self, expression):
-        try:
-            return POEngine.evaluate(self, expression)
-        except TALExpressionError:
-            pass
-
-    def evaluatePathOrVar(self, expr):
-        return 'who cares'
-
-    def translate(self, msgid, domain=None, mapping=None, default=None,
-                  position=None):
-        if msgid not in self.base:
-            POEngine.translate(self, msgid, domain, mapping, default, position)
-        return 'x'
-
-
-def main():
-    try:
-        opts, args = getopt.getopt(
-            sys.argv[1:],
-            'ho:u:',
-            ['help', 'output=', 'update='])
-    except getopt.error as msg:
-        usage(1, msg)
-
-    outfile = None
-    engine = None
-    update_mode = False
-    for opt, arg in opts:
-        if opt in ('-h', '--help'):
-            usage(0)
-        elif opt in ('-o', '--output'):
-            outfile = arg
-        elif opt in ('-u', '--update'):
-            update_mode = True
-            if outfile is None:
-                outfile = arg
-            engine = UpdatePOEngine(filename=arg)
-
-    if not args:
-        print('nothing to do')
-        return
-
-    # We don't care about the rendered output of the .pt file
-    class Devnull(object):
-        def write(self, s):
-            pass
-
-    # check if we've already instantiated an engine;
-    # if not, use the stupidest one available
-    if not engine:
-        engine = POEngine()
-
-    # process each file specified
-    for filename in args:
-        try:
-            engine.file = filename
-            p = HTMLTALParser()
-            p.parseFile(filename)
-            program, macros = p.getCode()
-            POTALInterpreter(program, macros, engine, stream=Devnull(),
-                             metal=False)()
-        except BaseException:  # Hee hee, I love bare excepts!
-            print('There was an error processing', filename)
-            traceback.print_exc()
-
-    # Now output the keys in the engine.  Write them to a file if --output or
-    # --update was specified; otherwise use standard out.
-    if (outfile is None):
-        outfile = sys.stdout
-    else:
-        outfile = file(outfile, update_mode and "a" or "w")
-
-    catalog = {}
-    for domain in engine.catalog:
-        catalog.update(engine.catalog[domain])
-
-    messages = catalog.copy()
-    try:
-        messages.update(engine.base)
-    except AttributeError:
-        pass
-    if '' not in messages:
-        print(pot_header % {'time': time.ctime(), 'version': __version__},
-              file=outfile)
-
-    # TODO: You should not sort by msgid, but by filename and position. (SR)
-    msgids = sorted(catalog)
-    for msgid in msgids:
-        positions = engine.catalog[msgid]
-        for filename, position in positions:
-            outfile.write('#: %s:%s\n' % (filename, position[0]))
-
-        outfile.write('msgid "%s"\n' % msgid)
-        outfile.write('msgstr ""\n')
-        outfile.write('\n')
-
-
-if __name__ == '__main__':
-    main()
diff --git a/src/zope/tal/talinterpreter.py b/src/zope/tal/talinterpreter.py
index 7e442d3..1070b94 100644
--- a/src/zope/tal/talinterpreter.py
+++ b/src/zope/tal/talinterpreter.py
@@ -13,28 +13,24 @@
 ##############################################################################
 """Interpreter for a pre-compiled TAL program.
 """
-import cgi
-import operator
+import html
 import sys
 
 from zope.i18nmessageid import Message
-from zope.tal.taldefs import quote, TAL_VERSION, METALError
+
+from zope.tal.taldefs import TAL_VERSION
+from zope.tal.taldefs import METALError
+from zope.tal.taldefs import getProgramMode
+from zope.tal.taldefs import getProgramVersion
 from zope.tal.taldefs import isCurrentVersion
-from zope.tal.taldefs import getProgramVersion, getProgramMode
+from zope.tal.taldefs import quote
 from zope.tal.talgenerator import TALGenerator
 from zope.tal.translationcontext import TranslationContext
 
-try:
-    unicode
-except NameError:
-    unicode = str  # Python 3.x
-_BLANK = u''
-
 
 # Avoid constructing this tuple over and over
 I18nMessageTypes = (Message,)
-
-TypesToTranslate = I18nMessageTypes + (str, unicode)
+TypesToTranslate = I18nMessageTypes + (str, )
 
 BOOLEAN_HTML_ATTRS = frozenset([
     # List of Boolean attributes in HTML that should be rendered in
@@ -92,7 +88,7 @@ class AltTALGenerator(TALGenerator):
 
 
 class MacroStackItem(list):
-    # This is a `list` subclass for backward compability.
+    # This is a `list` subclass for backward compatibility.
     """Stack entry for the TALInterpreter.macroStack.
 
     This offers convenience attributes for more readable access.
@@ -100,19 +96,36 @@ class MacroStackItem(list):
     """
     __slots__ = ()
 
-    # These would be nicer using @syntax, but that would require
-    # Python 2.4.x; this will do for now.
+    @property
+    def macroName(self):
+        return self[0]
+
+    @property
+    def slots(self):
+        return self[1]
+
+    @property
+    def definingName(self):
+        return self[2]
+
+    @property
+    def extending(self):
+        return self[3]
+
+    @property
+    def entering(self):
+        return self[4]
+
+    @entering.setter
+    def entering(self, value):
+        self[4] = value
 
-    macroName = property(lambda self: self[0])
-    slots = property(lambda self: self[1])
-    definingName = property(lambda self: self[2])
-    extending = property(lambda self: self[3])
-    entering = property(lambda self: self[4],
-                        lambda self, value: operator.setitem(self, 4, value))
-    i18nContext = property(lambda self: self[5])
+    @property
+    def i18nContext(self):
+        return self[5]
 
 
-class TALInterpreter(object):
+class TALInterpreter:
     """TAL interpreter.
 
     Some notes on source annotations.  They are HTML/XML comments added to the
@@ -219,7 +232,7 @@ class TALInterpreter(object):
         self.sourceAnnotations = sourceAnnotations
 
     def StringIO(self):
-        # Third-party products wishing to provide a full Unicode-aware
+        # Third-party products wishing to provide a full text-aware
         # StringIO can do so by monkey-patching this method.
         return FasterStringIO()
 
@@ -313,9 +326,9 @@ class TALInterpreter(object):
         if lineno is None:
             location = self.sourceFile
         else:
-            location = '%s (line %s)' % (self.sourceFile, lineno)
+            location = '{} (line {})'.format(self.sourceFile, lineno)
         sep = '=' * 78
-        return '<!--\n%s\n%s\n%s\n-->' % (sep, location, sep)
+        return '<!--\n{}\n{}\n{}\n-->'.format(sep, location, sep)
 
     def stream_write(self, s,
                      len=len):
@@ -335,8 +348,8 @@ class TALInterpreter(object):
         try:
             if self.debug:
                 for (opcode, args) in program:
-                    s = "%sdo_%s(%s)\n" % ("    " * self.level, opcode,
-                                           repr(args))
+                    s = "{}do_{}({})\n".format("    " * self.level, opcode,
+                                               repr(args))
                     if len(s) > 80:
                         s = s[:76] + "...\n"
                     sys.stderr.write(s)
@@ -451,9 +464,10 @@ class TALInterpreter(object):
                 defName = macs[0].definingName
                 res = []
                 if defName:
-                    res.append('%sdefine-macro=%s' % (prefix, quote(defName)))
+                    res.append(
+                        '{}define-macro={}'.format(prefix, quote(defName)))
                 if useName:
-                    res.append('%suse-macro=%s' % (prefix, quote(useName)))
+                    res.append('{}use-macro={}'.format(prefix, quote(useName)))
                 return res
             elif suffix == "define-slot":
                 name = prefix + "fill-slot"
@@ -465,7 +479,7 @@ class TALInterpreter(object):
         if value is None:
             value = name
         else:
-            value = "%s=%s" % (name, quote(value))
+            value = "{}={}".format(name, quote(value))
         return [value]
 
     def attrAction_tal(self, item):
@@ -502,7 +516,7 @@ class TALInterpreter(object):
                     value = translated
             if value is None:
                 value = name
-            return ["%s=%s" % (name, quote(value))]
+            return ["{}={}".format(name, quote(value))]
         else:
             return ()
     bytecode_handlers["<attrAction>"] = attrAction
@@ -682,7 +696,7 @@ class TALInterpreter(object):
                 value = self.translate(value)
 
             if not structure:
-                value = cgi.escape(unicode(value))
+                value = html.escape(str(value))
 
         # Either the i18n:name tag is nested inside an i18n:translate in which
         # case the last item on the stack has the i18n dictionary and string
@@ -731,7 +745,7 @@ class TALInterpreter(object):
         if len(stuff) > 2:
             obj = self.engine.evaluate(stuff[2])
         xlated_msgid = self.translate(msgid, default, i18ndict, obj)
-        # TODO: I can't decide whether we want to cgi escape the translated
+        # TODO: I can't decide whether we want to html.escape the translated
         # string or not.  OTOH not doing this could introduce a cross-site
         # scripting vector by allowing translators to sneak JavaScript into
         # translations.  OTOH, for implicit interpolation values, we don't
@@ -756,7 +770,7 @@ class TALInterpreter(object):
         if isinstance(structure, I18nMessageTypes):
             text = self.translate(structure)
         else:
-            text = unicode(structure)
+            text = str(structure)
         if not (repldict or self.strictinsert):
             # Take a shortcut, no error checking
             self.stream_write(text)
@@ -775,7 +789,7 @@ class TALInterpreter(object):
                 self.interpret(block)
             else:
                 if not isinstance(structure, TypesToTranslate):
-                    structure = unicode(structure)
+                    structure = str(structure)
                 text = self.translate(structure)
                 if not (repldict or self.strictinsert):
                     # Take a shortcut, no error checking
@@ -835,7 +849,7 @@ class TALInterpreter(object):
     def translate(self, msgid, default=None, i18ndict=None,
                   obj=None, domain=None):
         if default is None:
-            default = getattr(msgid, 'default', unicode(msgid))
+            default = getattr(msgid, 'default', str(msgid))
         if i18ndict is None:
             i18ndict = {}
         if domain is None:
@@ -997,7 +1011,7 @@ class TALInterpreter(object):
                 error = engine.createErrorInfo(exc, self.position)
             finally:
                 # Avoid traceback reference cycle due to the __traceback__
-                # attribute on Python 3.
+                # attribute.
                 del exc
             engine.setLocal('error', error)
             try:
@@ -1025,7 +1039,7 @@ class TALInterpreter(object):
 
 
 class FasterStringIO(list):
-    # Unicode-aware append-only version of StringIO.
+    # text-aware append-only version of StringIO.
     write = list.append
 
     def __init__(self, value=None):
@@ -1034,7 +1048,7 @@ class FasterStringIO(list):
             self.append(value)
 
     def getvalue(self):
-        return _BLANK.join(self)
+        return ''.join(self)
 
 
 def _write_ValueError(s):
diff --git a/src/zope/tal/talparser.py b/src/zope/tal/talparser.py
index d7d1964..d11fb86 100644
--- a/src/zope/tal/talparser.py
+++ b/src/zope/tal/talparser.py
@@ -15,7 +15,10 @@
 Parse XML and compile to :class:`~.TALInterpreter` intermediate code,
 using a :class:`~.TALGenerator`.
 """
-from zope.tal.taldefs import XML_NS, ZOPE_I18N_NS, ZOPE_METAL_NS, ZOPE_TAL_NS
+from zope.tal.taldefs import XML_NS
+from zope.tal.taldefs import ZOPE_I18N_NS
+from zope.tal.taldefs import ZOPE_METAL_NS
+from zope.tal.taldefs import ZOPE_TAL_NS
 from zope.tal.talgenerator import TALGenerator
 from zope.tal.xmlparser import XMLParser
 
@@ -125,7 +128,7 @@ class TALParser(XMLParser):
             prefix = self.nsDict[uri]
             prefixed = name
             if prefix:
-                prefixed = "%s:%s" % (prefix, name)
+                prefixed = "{}:{}".format(prefix, name)
             ns = self._namespaces.get(uri, "x")
             return (prefixed, name, ns)
         return (name, name, None)
@@ -146,8 +149,8 @@ def test():
         file = sys.argv[1]
     p.parseFile(file)
     program, macros = p.getCode()
-    from zope.tal.talinterpreter import TALInterpreter
     from zope.tal.dummyengine import DummyEngine
+    from zope.tal.talinterpreter import TALInterpreter
     engine = DummyEngine(macros)
     TALInterpreter(program, macros, engine, sys.stdout, wrap=0)()
 
diff --git a/src/zope/tal/tests/markbench.py b/src/zope/tal/tests/markbench.py
index 6dafa74..f3ae0ad 100644
--- a/src/zope/tal/tests/markbench.py
+++ b/src/zope/tal/tests/markbench.py
@@ -15,18 +15,21 @@
 """Run benchmarks of TAL vs. DTML
 """
 
-from __future__ import print_function
-from zope.tal.dummyengine import DummyEngine
-from zope.tal.talinterpreter import TALInterpreter
-from zope.tal.htmltalparser import HTMLTALParser
-from cStringIO import StringIO
+
 import errno
-import time
-import sys
 import getopt
 import os
-
+import sys
+import time
 import warnings
+
+from cStringIO import StringIO
+
+from zope.tal.dummyengine import DummyEngine
+from zope.tal.htmltalparser import HTMLTALParser
+from zope.tal.talinterpreter import TALInterpreter
+
+
 warnings.filterwarnings("ignore", category=DeprecationWarning)
 
 os.environ['NO_SECURITY'] = 'true'
@@ -191,6 +194,6 @@ if __name__ == "__main__":
         p.sort_stats('time', 'calls')
         try:
             p.print_stats(20)
-        except IOError as e:
+        except OSError as e:
             if e.errno != errno.EPIPE:
                 raise
diff --git a/src/zope/tal/tests/run.py b/src/zope/tal/tests/run.py
index 01a52c2..6e64e49 100644
--- a/src/zope/tal/tests/run.py
+++ b/src/zope/tal/tests/run.py
@@ -17,11 +17,12 @@
 import sys
 import unittest
 
-from zope.tal.tests import utils
-from zope.tal.tests import test_htmltalparser
-from zope.tal.tests import test_talinterpreter
 from zope.tal.tests import test_files
+from zope.tal.tests import test_htmltalparser
 from zope.tal.tests import test_sourcepos
+from zope.tal.tests import test_talinterpreter
+from zope.tal.tests import utils
+
 
 # TODO this code isn't picked up by the Zope 3 test framework..
 
diff --git a/src/zope/tal/tests/test_files.py b/src/zope/tal/tests/test_files.py
index 9ecefd1..4393eb1 100644
--- a/src/zope/tal/tests/test_files.py
+++ b/src/zope/tal/tests/test_files.py
@@ -18,18 +18,12 @@ import glob
 import os
 import sys
 import unittest
-
-try:
-    # Python 2.x
-    from cStringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
+from io import StringIO
 
 import zope.tal.runtest
-
 from zope.tal.tests import utils
 
+
 HERE = os.path.abspath(os.path.dirname(__file__))
 PARENTDIR = os.path.dirname(HERE)
 PREFIX = os.path.join(HERE, "input", "test*.")
diff --git a/src/zope/tal/tests/test_htmltalparser.py b/src/zope/tal/tests/test_htmltalparser.py
index ba2770b..db5bd0c 100644
--- a/src/zope/tal/tests/test_htmltalparser.py
+++ b/src/zope/tal/tests/test_htmltalparser.py
@@ -16,7 +16,8 @@
 import pprint
 import unittest
 
-from zope.tal import htmltalparser, taldefs
+from zope.tal import htmltalparser
+from zope.tal import taldefs
 
 
 class TestCaseBase(unittest.TestCase):
@@ -1057,11 +1058,3 @@ translated string</span>
             ('endScope', ()),
             ('rawtextColumn', ('</p>\n', 0))
         ])
-
-
-def test_suite():
-    return unittest.TestSuite((
-        unittest.makeSuite(HTMLTALParserTestCases),
-        unittest.makeSuite(METALGeneratorTestCases),
-        unittest.makeSuite(TALGeneratorTestCases),
-    ))
diff --git a/src/zope/tal/tests/test_sourcepos.py b/src/zope/tal/tests/test_sourcepos.py
index bcbd909..f9a84d5 100644
--- a/src/zope/tal/tests/test_sourcepos.py
+++ b/src/zope/tal/tests/test_sourcepos.py
@@ -14,18 +14,12 @@
 """Tests for TALInterpreter.
 """
 import unittest
+from io import StringIO
 
-try:
-    # Python 2.x
-    from StringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
-
+from zope.tal.dummyengine import DummyEngine
 from zope.tal.htmltalparser import HTMLTALParser
-from zope.tal.talinterpreter import TALInterpreter
 from zope.tal.talgenerator import TALGenerator
-from zope.tal.dummyengine import DummyEngine
+from zope.tal.talinterpreter import TALInterpreter
 
 
 page1 = '''<html metal:use-macro="main"><body>
@@ -89,4 +83,4 @@ class SourcePosTestCase(unittest.TestCase):
 
 
 def test_suite():
-    return unittest.makeSuite(SourcePosTestCase)
+    return unittest.defaultTestLoader.loadTestsFromTestCase(SourcePosTestCase)
diff --git a/src/zope/tal/tests/test_talgettext.py b/src/zope/tal/tests/test_talgettext.py
index 1559e83..fedead8 100644
--- a/src/zope/tal/tests/test_talgettext.py
+++ b/src/zope/tal/tests/test_talgettext.py
@@ -14,22 +14,15 @@
 """Tests for the talgettext utility.
 """
 
-from __future__ import print_function
 
 import tempfile
 import unittest
 import warnings
-
-try:
-    # Python 2.x
-    from StringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
+from io import StringIO
 
 from zope.tal.htmltalparser import HTMLTALParser
-from zope.tal.talgettext import POTALInterpreter
 from zope.tal.talgettext import POEngine
+from zope.tal.talgettext import POTALInterpreter
 
 
 class test_POEngine(unittest.TestCase):
@@ -75,10 +68,10 @@ class test_POEngine(unittest.TestCase):
         engine.file = 'psc_release_listing.pt'
         # position is position in file.
         engine.translate('foo', 'domain',
-                         default=u'Read more\u2026', position=7)
+                         default='Read more\u2026', position=7)
         # Adding the same key with the same default is fine.
         engine.translate('foo', 'domain',
-                         default=u'Read more\u2026', position=13)
+                         default='Read more\u2026', position=13)
         # Adding the same key with a different default is bad and
         # triggers a warning.
         with warnings.catch_warnings(record=True) as log:
diff --git a/src/zope/tal/tests/test_talinterpreter.py b/src/zope/tal/tests/test_talinterpreter.py
index 26c35cf..6252713 100644
--- a/src/zope/tal/tests/test_talinterpreter.py
+++ b/src/zope/tal/tests/test_talinterpreter.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 ##############################################################################
 #
 # Copyright (c) 2001, 2002 Zope Foundation and Contributors.
@@ -15,27 +14,21 @@
 """Tests for TALInterpreter.
 """
 import os
-
-import sys
 import unittest
+from io import StringIO
 
-try:
-    # Python 2.x
-    from StringIO import StringIO
-except ImportError:
-    # Python 3.x
-    from io import StringIO
-
+from zope.i18nmessageid import Message
 
-from zope.tal.taldefs import METALError, I18NError, TAL_VERSION
-from zope.tal.taldefs import TALExpressionError
-from zope.tal.htmltalparser import HTMLTALParser
-from zope.tal.talparser import TALParser
-from zope.tal.talinterpreter import TALInterpreter
-from zope.tal.talgenerator import TALGenerator
 from zope.tal.dummyengine import DummyEngine
 from zope.tal.dummyengine import MultipleDomainsDummyEngine
-from zope.i18nmessageid import Message
+from zope.tal.htmltalparser import HTMLTALParser
+from zope.tal.taldefs import TAL_VERSION
+from zope.tal.taldefs import I18NError
+from zope.tal.taldefs import METALError
+from zope.tal.taldefs import TALExpressionError
+from zope.tal.talgenerator import TALGenerator
+from zope.tal.talinterpreter import TALInterpreter
+from zope.tal.talparser import TALParser
 
 
 class TestCaseBase(unittest.TestCase):
@@ -466,8 +459,7 @@ class I18NCornerTestCaseMessage(TestCaseBase):
         self.interpreter = TALInterpreter(program, {}, self.engine,
                                           stream=result)
         self.interpreter()
-        msgids = self.engine.translationDomain.getMsgids('default')
-        msgids.sort()
+        msgids = sorted(self.engine.translationDomain.getMsgids('default'))
         self.assertEqual(1, len(msgids))
         self.assertEqual('This is text <b> for</b> barvalue.', msgids[0][0])
         self.assertEqual(
@@ -490,7 +482,7 @@ class I18NCornerTestCaseMessage(TestCaseBase):
         self.assertEqual('This is text for ${bar}.', msgids[1][0])
         self.assertEqual({'bar': '<pre> \tBAR\n </pre>'}, msgids[1][1])
         self.assertEqual(
-            (u'<div>THIS IS TEXT FOR <pre> \tBAR\n </pre>.</div>'),
+            ('<div>THIS IS TEXT FOR <pre> \tBAR\n </pre>.</div>'),
             result.getvalue())
 
     def test_for_handling_unicode_vars(self):
@@ -499,7 +491,7 @@ class I18NCornerTestCaseMessage(TestCaseBase):
         program, _macros = self._compile(
             r'''<div i18n:translate='' tal:define='bar python:u"\u00C0"'>'''
             r'''Foo <span tal:replace='bar' i18n:name='bar' /></div>''')
-        self._check(program, (u"<div>FOO \u00C0</div>"))
+        self._check(program, ("<div>FOO \u00C0</div>"))
 
 
 class UnusedExplicitDomainTestCase(I18NCornerTestCaseMessage):
@@ -708,13 +700,13 @@ class OutputPresentationTestCase(TestCaseBase):
         self.compare(INPUT, EXPECTED)
 
     def test_unicode_content(self):
-        INPUT = u"""<p tal:content="python:u'déjà-vu'">para</p>"""
-        EXPECTED = u'<p>d\xe9j\xe0-vu</p>'
+        INPUT = """<p tal:content="python:u'déjà-vu'">para</p>"""
+        EXPECTED = '<p>d\xe9j\xe0-vu</p>'
         self.compare(INPUT, EXPECTED)
 
     def test_unicode_structure(self):
-        INPUT = u"""<p tal:replace="structure python:u'déjà-vu'">para</p>"""
-        EXPECTED = u'd\xe9j\xe0-vu'
+        INPUT = """<p tal:replace="structure python:u'déjà-vu'">para</p>"""
+        EXPECTED = 'd\xe9j\xe0-vu'
         self.compare(INPUT, EXPECTED)
 
     def test_i18n_replace_number(self):
@@ -722,30 +714,16 @@ class OutputPresentationTestCase(TestCaseBase):
         <p i18n:translate="foo ${bar}">
         <span tal:replace="python:123" i18n:name="bar">para</span>
         </p>"""
-        EXPECTED = (u"""
+        EXPECTED = ("""
         <p>FOO 123</p>""")
         self.compare(INPUT, EXPECTED)
 
     def test_entities(self):
-        if sys.version_info[:2] <= (3, 2):
-            # HTMLParser.HTMLParser in Python 2.x--3.2 parses "&#45" as "&#45"
-            INPUT = ('<img tal:define="foo nothing" '
-                     'alt="&a; &#1; &#x0a; &a &#45 &; <>" />')
-            EXPECTED = ('<img alt="&a; \x01 \n '
-                        '&amp;a &amp;#45 &amp;; &lt;&gt;" />')
-        elif sys.version_info < (3, 4):
-            # html.parser.HTMLParser in Python 3.3 parses "&#45" as "-"
-            INPUT = ('<img tal:define="foo nothing" '
-                     'alt="&a; &#1; &#x0a; &a &#45 &; <>" />')
-            EXPECTED = ('<img alt="&a; \x01 \n '
-                        '&amp;a - &amp;; &lt;&gt;" />')
-        else:
-            # html.parser.HTMLParser in Python 3.4 parses "&#1" as ""
-            # because '1' is an "invalid codepoint".
-            INPUT = ('<img tal:define="foo nothing" '
-                     'alt="&a; &#1; &#x0a; &a &#45 &; <>" />')
-            EXPECTED = ('<img alt="&a;  \n '
-                        '&amp;a - &amp;; &lt;&gt;" />')
+        # Python parses "&#1" as "" because '1' is an "invalid codepoint".
+        INPUT = ('<img tal:define="foo nothing" '
+                 'alt="&a; &#1; &#x0a; &a &#45 &; <>" />')
+        EXPECTED = ('<img alt="&a;  \n '
+                    '&amp;a - &amp;; &lt;&gt;" />')
         self.compare(INPUT, EXPECTED)
 
     def compare(self, INPUT, EXPECTED):
diff --git a/src/zope/tal/tests/test_talparser.py b/src/zope/tal/tests/test_talparser.py
index 58c8609..35c611b 100644
--- a/src/zope/tal/tests/test_talparser.py
+++ b/src/zope/tal/tests/test_talparser.py
@@ -34,4 +34,4 @@ class TALParserTestCase(unittest.TestCase):
 
 
 def test_suite():
-    return unittest.makeSuite(TALParserTestCase)
+    return unittest.defaultTestLoader.loadTestsFromTestCase(TALParserTestCase)
diff --git a/src/zope/tal/tests/test_xmlparser.py b/src/zope/tal/tests/test_xmlparser.py
index 437d68f..c02d652 100644
--- a/src/zope/tal/tests/test_xmlparser.py
+++ b/src/zope/tal/tests/test_xmlparser.py
@@ -81,7 +81,7 @@ class EventCollectorExtra(EventCollector):
         self.append(("starttag_text", self.get_starttag_text()))
 
 
-class SegmentedFile(object):
+class SegmentedFile:
     def __init__(self, parts):
         self.parts = list(parts)
 
@@ -253,10 +253,10 @@ text
         self._parse_error("<!DOCTYPE foo $ >")
 
     def test_unicode_string(self):
-        output = [('starttag', u'p', []),
-                  ('data', u'\xe4\xf6\xfc\xdf'),
-                  ('endtag', u'p')]
-        self._run_check(u'<p>\xe4\xf6\xfc\xdf</p>', output)
+        output = [('starttag', 'p', []),
+                  ('data', '\xe4\xf6\xfc\xdf'),
+                  ('endtag', 'p')]
+        self._run_check('<p>\xe4\xf6\xfc\xdf</p>', output)
 
 
 # Support for the Zope regression test framework:
diff --git a/src/zope/tal/tests/utils.py b/src/zope/tal/tests/utils.py
index b8d384d..36cf2a8 100644
--- a/src/zope/tal/tests/utils.py
+++ b/src/zope/tal/tests/utils.py
@@ -13,9 +13,10 @@
 ##############################################################################
 """Helper functions for the test suite.
 """
-import unittest
 import os
 import sys
+import unittest
+
 
 mydir = os.path.abspath(os.path.dirname(__file__))
 codedir = os.path.dirname(os.path.dirname(os.path.dirname(mydir)))
diff --git a/src/zope/tal/timer.py b/src/zope/tal/timer.py
index f64654f..1395515 100644
--- a/src/zope/tal/timer.py
+++ b/src/zope/tal/timer.py
@@ -20,7 +20,8 @@ import time
 
 from cStringIO import StringIO
 
-from zope.tal.driver import compilefile, interpretit
+from zope.tal.driver import compilefile
+from zope.tal.driver import interpretit
 
 
 def main():
diff --git a/src/zope/tal/translationcontext.py b/src/zope/tal/translationcontext.py
index e515628..7d12b8f 100644
--- a/src/zope/tal/translationcontext.py
+++ b/src/zope/tal/translationcontext.py
@@ -19,7 +19,7 @@ needed to perform translation of a marked string from a page template.
 DEFAULT_DOMAIN = "default"
 
 
-class TranslationContext(object):
+class TranslationContext:
     """Information about the I18N settings of a TAL processor."""
 
     def __init__(self, parent=None, domain=None, target=None, source=None):
diff --git a/src/zope/tal/xmlparser.py b/src/zope/tal/xmlparser.py
index 7ebee73..f4891f9 100644
--- a/src/zope/tal/xmlparser.py
+++ b/src/zope/tal/xmlparser.py
@@ -16,22 +16,10 @@
 This creates a parser with namespace processing enabled.
 """
 import logging
+from urllib.request import urlopen
 
-try:
-    # Python 2.x
-    from urllib import urlopen
-except ImportError:
-    # Python 3.x
-    from urllib.request import urlopen
 
-
-try:
-    unicode
-except NameError:
-    unicode = str  # Python 3.x
-
-
-class XMLParser(object):
+class XMLParser:
     """
     Parse XML using :mod:`xml.parsers.expat`.
     """
@@ -91,9 +79,9 @@ class XMLParser(object):
 
     def parseString(self, s):
         """Parse the given string."""
-        if isinstance(s, unicode):
-            # Expat cannot deal with unicode strings, only with
-            # encoded ones.  Also, its range of encodings is rather
+        if isinstance(s, str):
+            # Expat cannot deal with str, only with
+            # bytes.  Also, its range of encodings is rather
             # limited, UTF-8 is the safest bet here.
             s = s.encode('utf-8')
         self.parser.Parse(s, 1)
diff --git a/tox.ini b/tox.ini
index 4ef11c7..442ee82 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,14 +4,11 @@
 minversion = 3.18
 envlist =
     lint
-    py27
-    py35
-    py36
     py37
     py38
     py39
     py310
-    pypy
+    py311
     pypy3
     docs
     coverage
@@ -27,15 +24,26 @@ extras =
 [testenv:lint]
 basepython = python3
 skip_install = true
+commands =
+    isort --check-only --diff {toxinidir}/src {toxinidir}/setup.py
+    flake8 src setup.py
+    check-manifest
+    check-python-versions
 deps =
-    flake8
     check-manifest
     check-python-versions >= 0.19.1
     wheel
+    flake8
+    isort
+
+[testenv:isort-apply]
+basepython = python3
+skip_install = true
+commands_pre =
+deps =
+    isort
 commands =
-    flake8 src setup.py
-    check-manifest
-    check-python-versions
+    isort {toxinidir}/src {toxinidir}/setup.py []
 
 [testenv:docs]
 basepython = python3
@@ -52,16 +60,14 @@ allowlist_externals =
     mkdir
 deps =
     coverage
-    coverage-python-version
 commands =
     mkdir -p {toxinidir}/parts/htmlcov
     coverage run -m zope.testrunner --test-path=src {posargs:-vc}
-    coverage html
-    coverage report -m --fail-under=81
+    coverage html --ignore-errors
+    coverage report --ignore-errors --show-missing --fail-under=84
 
 [coverage:run]
 branch = True
-plugins = coverage_python_version
 source = zope.tal
 
 [coverage:report]