Merge branch 'master' into drop-py26

6 files changed, 688 insertions, 67 deletions

diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py
index d8000b00..497448de 100644
--- a/pkg_resources/__init__.py
+++ b/pkg_resources/__init__.py
@@ -34,9 +34,11 @@ import platform
 import collections
 import plistlib
 import email.parser
+import errno
 import tempfile
 import textwrap
 import itertools
+import inspect
 from pkgutil import get_importer
 
 try:
@@ -67,6 +69,7 @@ try:
 except ImportError:
     importlib_machinery = None
 
+from . import py31compat
 from pkg_resources.extern import appdirs
 from pkg_resources.extern import packaging
 __import__('pkg_resources.extern.packaging.version')
@@ -74,9 +77,15 @@ __import__('pkg_resources.extern.packaging.specifiers')
 __import__('pkg_resources.extern.packaging.requirements')
 __import__('pkg_resources.extern.packaging.markers')
 
+
 if (3, 0) < sys.version_info < (3, 3):
     raise RuntimeError("Python 3.3 or later is required")
 
+if six.PY2:
+    # Those builtin exceptions are only defined in Python 3
+    PermissionError = None
+    NotADirectoryError = None
+
 # declare some globals that will be defined later to
 # satisfy the linters.
 require = None
@@ -786,7 +795,7 @@ class WorkingSet(object):
         self._added_new(dist)
 
     def resolve(self, requirements, env=None, installer=None,
-            replace_conflicting=False):
+                replace_conflicting=False, extras=None):
         """List all distributions needed to (recursively) meet `requirements`
 
         `requirements` must be a sequence of ``Requirement`` objects.  `env`,
@@ -802,6 +811,12 @@ class WorkingSet(object):
         the wrong version.  Otherwise, if an `installer` is supplied it will be
         invoked to obtain the correct version of the requirement and activate
         it.
+
+        `extras` is a list of the extras to be used with these requirements.
+        This is important because extra requirements may look like `my_req;
+        extra = "my_extra"`, which would otherwise be interpreted as a purely
+        optional requirement.  Instead, we want to be able to assert that these
+        requirements are truly required.
         """
 
         # set up the stack
@@ -825,7 +840,7 @@ class WorkingSet(object):
                 # Ignore cyclic or redundant dependencies
                 continue
 
-            if not req_extras.markers_pass(req):
+            if not req_extras.markers_pass(req, extras):
                 continue
 
             dist = best.get(req.key)
@@ -843,7 +858,10 @@ class WorkingSet(object):
                             # distribution
                             env = Environment([])
                             ws = WorkingSet([])
-                    dist = best[req.key] = env.best_match(req, ws, installer)
+                    dist = best[req.key] = env.best_match(
+                        req, ws, installer,
+                        replace_conflicting=replace_conflicting
+                    )
                     if dist is None:
                         requirers = required_by.get(req, None)
                         raise DistributionNotFound(req, requirers)
@@ -1004,7 +1022,7 @@ class _ReqExtras(dict):
     Map each requirement to the extras that demanded it.
     """
 
-    def markers_pass(self, req):
+    def markers_pass(self, req, extras=None):
         """
         Evaluate markers for req against each extra that
         demanded it.
@@ -1014,7 +1032,7 @@ class _ReqExtras(dict):
         """
         extra_evals = (
             req.marker.evaluate({'extra': extra})
-            for extra in self.get(req, ()) + (None,)
+            for extra in self.get(req, ()) + (extras or (None,))
         )
         return not req.marker or any(extra_evals)
 
@@ -1095,7 +1113,7 @@ class Environment(object):
                 dists.append(dist)
                 dists.sort(key=operator.attrgetter('hashcmp'), reverse=True)
 
-    def best_match(self, req, working_set, installer=None):
+    def best_match(self, req, working_set, installer=None, replace_conflicting=False):
         """Find distribution best matching `req` and usable on `working_set`
 
         This calls the ``find(req)`` method of the `working_set` to see if a
@@ -1108,7 +1126,12 @@ class Environment(object):
         calling the environment's ``obtain(req, installer)`` method will be
         returned.
         """
-        dist = working_set.find(req)
+        try:
+            dist = working_set.find(req)
+        except VersionConflict:
+            if not replace_conflicting:
+                raise
+            dist = None
         if dist is not None:
             return dist
         for dist in self[req.key]:
@@ -1544,7 +1567,7 @@ class EggProvider(NullProvider):
         path = self.module_path
         old = None
         while path != old:
-            if _is_unpacked_egg(path):
+            if _is_egg_path(path):
                 self.egg_name = os.path.basename(path)
                 self.egg_info = os.path.join(path, 'EGG-INFO')
                 self.egg_root = path
@@ -1927,10 +1950,16 @@ def find_eggs_in_zip(importer, path_item, only=False):
         # don't yield nested distros
         return
     for subitem in metadata.resource_listdir('/'):
-        if _is_unpacked_egg(subitem):
+        if _is_egg_path(subitem):
             subpath = os.path.join(path_item, subitem)
             for dist in find_eggs_in_zip(zipimport.zipimporter(subpath), subpath):
                 yield dist
+        elif subitem.lower().endswith('.dist-info'):
+            subpath = os.path.join(path_item, subitem)
+            submeta = EggMetadata(zipimport.zipimporter(subpath))
+            submeta.egg_info = subpath
+            yield Distribution.from_location(path_item, subitem, submeta)
+
 
 
 register_finder(zipimport.zipimporter, find_eggs_in_zip)
@@ -1973,46 +2002,57 @@ def find_on_path(importer, path_item, only=False):
     """Yield distributions accessible on a sys.path directory"""
     path_item = _normalize_cached(path_item)
 
-    if os.path.isdir(path_item) and os.access(path_item, os.R_OK):
-        if _is_unpacked_egg(path_item):
-            yield Distribution.from_filename(
-                path_item, metadata=PathMetadata(
-                    path_item, os.path.join(path_item, 'EGG-INFO')
-                )
+    if _is_unpacked_egg(path_item):
+        yield Distribution.from_filename(
+            path_item, metadata=PathMetadata(
+                path_item, os.path.join(path_item, 'EGG-INFO')
             )
-        else:
-            # scan for .egg and .egg-info in directory
-            path_item_entries = _by_version_descending(os.listdir(path_item))
-            for entry in path_item_entries:
-                lower = entry.lower()
-                if lower.endswith('.egg-info') or lower.endswith('.dist-info'):
-                    fullpath = os.path.join(path_item, entry)
-                    if os.path.isdir(fullpath):
-                        # egg-info directory, allow getting metadata
-                        if len(os.listdir(fullpath)) == 0:
-                            # Empty egg directory, skip.
-                            continue
-                        metadata = PathMetadata(path_item, fullpath)
-                    else:
-                        metadata = FileMetadata(fullpath)
-                    yield Distribution.from_location(
-                        path_item, entry, metadata, precedence=DEVELOP_DIST
-                    )
-                elif not only and _is_unpacked_egg(entry):
-                    dists = find_distributions(os.path.join(path_item, entry))
-                    for dist in dists:
-                        yield dist
-                elif not only and lower.endswith('.egg-link'):
-                    with open(os.path.join(path_item, entry)) as entry_file:
-                        entry_lines = entry_file.readlines()
-                    for line in entry_lines:
-                        if not line.strip():
-                            continue
-                        path = os.path.join(path_item, line.rstrip())
-                        dists = find_distributions(path)
-                        for item in dists:
-                            yield item
-                        break
+        )
+    else:
+        try:
+            entries = os.listdir(path_item)
+        except (PermissionError, NotADirectoryError):
+            return
+        except OSError as e:
+            # Ignore the directory if does not exist, not a directory or we
+            # don't have permissions
+            if (e.errno in (errno.ENOTDIR, errno.EACCES, errno.ENOENT)
+                # Python 2 on Windows needs to be handled this way :(
+               or hasattr(e, "winerror") and e.winerror == 267):
+                return
+            raise
+        # scan for .egg and .egg-info in directory
+        path_item_entries = _by_version_descending(entries)
+        for entry in path_item_entries:
+            lower = entry.lower()
+            if lower.endswith('.egg-info') or lower.endswith('.dist-info'):
+                fullpath = os.path.join(path_item, entry)
+                if os.path.isdir(fullpath):
+                    # egg-info directory, allow getting metadata
+                    if len(os.listdir(fullpath)) == 0:
+                        # Empty egg directory, skip.
+                        continue
+                    metadata = PathMetadata(path_item, fullpath)
+                else:
+                    metadata = FileMetadata(fullpath)
+                yield Distribution.from_location(
+                    path_item, entry, metadata, precedence=DEVELOP_DIST
+                )
+            elif not only and _is_egg_path(entry):
+                dists = find_distributions(os.path.join(path_item, entry))
+                for dist in dists:
+                    yield dist
+            elif not only and lower.endswith('.egg-link'):
+                with open(os.path.join(path_item, entry)) as entry_file:
+                    entry_lines = entry_file.readlines()
+                for line in entry_lines:
+                    if not line.strip():
+                        continue
+                    path = os.path.join(path_item, line.rstrip())
+                    dists = find_distributions(path)
+                    for item in dists:
+                        yield item
+                    break
 
 
 register_finder(pkgutil.ImpImporter, find_on_path)
@@ -2093,6 +2133,10 @@ def _rebuild_mod_path(orig_path, package_name, module):
         parts = path_parts[:-module_parts]
         return safe_sys_path_index(_normalize_cached(os.sep.join(parts)))
 
+    if not isinstance(orig_path, list):
+        # Is this behavior useful when module.__path__ is not a list?
+        return
+
     orig_path.sort(key=position_in_sys_path)
     module.__path__[:] = [_normalize_cached(p) for p in orig_path]
 
@@ -2182,12 +2226,22 @@ def _normalize_cached(filename, _cache={}):
         return result
 
 
+def _is_egg_path(path):
+    """
+    Determine if given path appears to be an egg.
+    """
+    return (
+        path.lower().endswith('.egg')
+    )
+
+
 def _is_unpacked_egg(path):
     """
     Determine if given path appears to be an unpacked egg.
     """
     return (
-        path.lower().endswith('.egg')
+        _is_egg_path(path) and
+        os.path.isfile(os.path.join(path, 'EGG-INFO', 'PKG-INFO'))
     )
 
 
@@ -2279,8 +2333,14 @@ class EntryPoint(object):
     def require(self, env=None, installer=None):
         if self.extras and not self.dist:
             raise UnknownExtra("Can't require() without a distribution", self)
+
+        # Get the requirements for this entry point with all its extras and
+        # then resolve them. We have to pass `extras` along when resolving so
+        # that the working set knows what extras we want. Otherwise, for
+        # dist-info distributions, the working set will assume that the
+        # requirements for that extra are purely optional and skip over them.
         reqs = self.dist.requires(self.extras)
-        items = working_set.resolve(reqs, env, installer)
+        items = working_set.resolve(reqs, env, installer, extras=self.extras)
         list(map(working_set.add, items))
 
     pattern = re.compile(
@@ -2895,20 +2955,20 @@ class Requirement(packaging.requirements.Requirement):
         return req
 
 
-def _get_mro(cls):
-    """Get an mro for a type or classic class"""
-    if not isinstance(cls, type):
-
-        class cls(cls, object):
-            pass
-
-        return cls.__mro__[1:]
-    return cls.__mro__
+def _always_object(classes):
+    """
+    Ensure object appears in the mro even
+    for old-style classes.
+    """
+    if object not in classes:
+        return classes + (object,)
+    return classes
 
 
 def _find_adapter(registry, ob):
     """Return an adapter factory for `ob` from `registry`"""
-    for t in _get_mro(getattr(ob, '__class__', type(ob))):
+    types = _always_object(inspect.getmro(getattr(ob, '__class__', type(ob))))
+    for t in types:
         if t in registry:
             return registry[t]
 
@@ -2916,8 +2976,7 @@ def _find_adapter(registry, ob):
 def ensure_directory(path):
     """Ensure that the parent directory of `path` exists"""
     dirname = os.path.dirname(path)
-    if not os.path.isdir(dirname):
-        os.makedirs(dirname)
+    py31compat.makedirs(dirname, exist_ok=True)
 
 
 def _bypass_ensure_directory(path):
diff --git a/pkg_resources/py31compat.py b/pkg_resources/py31compat.py
new file mode 100644
index 00000000..331a51bb
--- /dev/null
+++ b/pkg_resources/py31compat.py
@@ -0,0 +1,22 @@
+import os
+import errno
+import sys
+
+
+def _makedirs_31(path, exist_ok=False):
+    try:
+        os.makedirs(path)
+    except OSError as exc:
+        if not exist_ok or exc.errno != errno.EEXIST:
+            raise
+
+
+# rely on compatibility behavior until mode considerations
+#  and exists_ok considerations are disentangled.
+# See https://github.com/pypa/setuptools/pull/1083#issuecomment-315168663
+needs_makedirs = (
+    sys.version_info < (3, 2, 5) or
+    (3, 3) <= sys.version_info < (3, 3, 6) or
+    (3, 4) <= sys.version_info < (3, 4, 1)
+)
+makedirs = _makedirs_31 if needs_makedirs else os.makedirs
diff --git a/pkg_resources/tests/test_find_distributions.py b/pkg_resources/tests/test_find_distributions.py
new file mode 100644
index 00000000..97999b33
--- /dev/null
+++ b/pkg_resources/tests/test_find_distributions.py
@@ -0,0 +1,65 @@
+import subprocess
+import sys
+
+import pytest
+import pkg_resources
+
+SETUP_TEMPLATE = """
+import setuptools
+setuptools.setup(
+    name="my-test-package",
+    version="1.0",
+    zip_safe=True,
+)
+""".lstrip()
+
+class TestFindDistributions:
+
+    @pytest.fixture
+    def target_dir(self, tmpdir):
+        target_dir = tmpdir.mkdir('target')
+        # place a .egg named directory in the target that is not an egg:
+        target_dir.mkdir('not.an.egg')
+        return str(target_dir)
+
+    @pytest.fixture
+    def project_dir(self, tmpdir):
+        project_dir = tmpdir.mkdir('my-test-package')
+        (project_dir / "setup.py").write(SETUP_TEMPLATE)
+        return str(project_dir)
+
+    def test_non_egg_dir_named_egg(self, target_dir):
+        dists = pkg_resources.find_distributions(target_dir)
+        assert not list(dists)
+
+    def test_standalone_egg_directory(self, project_dir, target_dir):
+        # install this distro as an unpacked egg:
+        args = [
+            sys.executable,
+            '-c', 'from setuptools.command.easy_install import main; main()',
+            '-mNx',
+            '-d', target_dir,
+            '--always-unzip',
+            project_dir,
+        ]
+        subprocess.check_call(args)
+        dists = pkg_resources.find_distributions(target_dir)
+        assert [dist.project_name for dist in dists] == ['my-test-package']
+        dists = pkg_resources.find_distributions(target_dir, only=True)
+        assert not list(dists)
+
+    def test_zipped_egg(self, project_dir, target_dir):
+        # install this distro as an unpacked egg:
+        args = [
+            sys.executable,
+            '-c', 'from setuptools.command.easy_install import main; main()',
+            '-mNx',
+            '-d', target_dir,
+            '--zip-ok',
+            project_dir,
+        ]
+        subprocess.check_call(args)
+        dists = pkg_resources.find_distributions(target_dir)
+        assert [dist.project_name for dist in dists] == ['my-test-package']
+        dists = pkg_resources.find_distributions(target_dir, only=True)
+        assert not list(dists)
diff --git a/pkg_resources/tests/test_markers.py b/pkg_resources/tests/test_markers.py
index 78810b6e..15a3b499 100644
--- a/pkg_resources/tests/test_markers.py
+++ b/pkg_resources/tests/test_markers.py
@@ -1,7 +1,4 @@
-try:
-    import unittest.mock as mock
-except ImportError:
-    import mock
+import mock
 
 from pkg_resources import evaluate_marker
 
diff --git a/pkg_resources/tests/test_resources.py b/pkg_resources/tests/test_resources.py
index 8223963c..dcd2f42c 100644
--- a/pkg_resources/tests/test_resources.py
+++ b/pkg_resources/tests/test_resources.py
@@ -585,7 +585,7 @@ class TestParsing:
             [Requirement('Twis-Ted>=1.2-1')]
         )
         assert (
-            list(parse_requirements('Twisted >=1.2, \ # more\n<2.0'))
+            list(parse_requirements('Twisted >=1.2, \\ # more\n<2.0'))
             ==
             [Requirement('Twisted>=1.2,<2.0')]
         )
diff --git a/pkg_resources/tests/test_working_set.py b/pkg_resources/tests/test_working_set.py
new file mode 100644
index 00000000..422a7283
--- /dev/null
+++ b/pkg_resources/tests/test_working_set.py
@@ -0,0 +1,478 @@
+import inspect
+import re
+import textwrap
+
+import pytest
+
+import pkg_resources
+
+from .test_resources import Metadata
+
+
+def strip_comments(s):
+    return '\n'.join(
+        l for l in s.split('\n')
+        if l.strip() and not l.strip().startswith('#')
+    )
+
+def parse_distributions(s):
+    '''
+    Parse a series of distribution specs of the form:
+    {project_name}-{version}
+       [optional, indented requirements specification]
+
+    Example:
+
+        foo-0.2
+        bar-1.0
+          foo>=3.0
+          [feature]
+          baz
+
+    yield 2 distributions:
+        - project_name=foo, version=0.2
+        - project_name=bar, version=1.0, requires=['foo>=3.0', 'baz; extra=="feature"']
+    '''
+    s = s.strip()
+    for spec in re.split('\n(?=[^\s])', s):
+        if not spec:
+            continue
+        fields = spec.split('\n', 1)
+        assert 1 <= len(fields) <= 2
+        name, version = fields.pop(0).split('-')
+        if fields:
+            requires = textwrap.dedent(fields.pop(0))
+            metadata=Metadata(('requires.txt', requires))
+        else:
+            metadata = None
+        dist = pkg_resources.Distribution(project_name=name,
+                                          version=version,
+                                          metadata=metadata)
+        yield dist
+
+
+class FakeInstaller(object):
+
+    def __init__(self, installable_dists):
+        self._installable_dists = installable_dists
+
+    def __call__(self, req):
+        return next(iter(filter(lambda dist: dist in req,
+                                self._installable_dists)), None)
+
+
+def parametrize_test_working_set_resolve(*test_list):
+    idlist = []
+    argvalues = []
+    for test in test_list:
+        (
+            name,
+            installed_dists,
+            installable_dists,
+            requirements,
+            expected1, expected2
+        ) = [
+            strip_comments(s.lstrip()) for s in
+            textwrap.dedent(test).lstrip().split('\n\n', 5)
+        ]
+        installed_dists = list(parse_distributions(installed_dists))
+        installable_dists = list(parse_distributions(installable_dists))
+        requirements = list(pkg_resources.parse_requirements(requirements))
+        for id_, replace_conflicting, expected in (
+            (name, False, expected1),
+            (name + '_replace_conflicting', True, expected2),
+        ):
+            idlist.append(id_)
+            expected = strip_comments(expected.strip())
+            if re.match('\w+$', expected):
+                expected = getattr(pkg_resources, expected)
+                assert issubclass(expected, Exception)
+            else:
+                expected = list(parse_distributions(expected))
+            argvalues.append(pytest.param(installed_dists, installable_dists,
+                                          requirements, replace_conflicting,
+                                          expected))
+    return pytest.mark.parametrize('installed_dists,installable_dists,'
+                                   'requirements,replace_conflicting,'
+                                   'resolved_dists_or_exception',
+                                   argvalues, ids=idlist)
+
+
+@parametrize_test_working_set_resolve(
+    '''
+    # id
+    noop
+
+    # installed
+
+    # installable
+
+    # wanted
+
+    # resolved
+
+    # resolved [replace conflicting]
+    ''',
+
+    '''
+    # id
+    already_installed
+
+    # installed
+    foo-3.0
+
+    # installable
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    foo-3.0
+
+    # resolved [replace conflicting]
+    foo-3.0
+    ''',
+
+    '''
+    # id
+    installable_not_installed
+
+    # installed
+
+    # installable
+    foo-3.0
+    foo-4.0
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    foo-3.0
+
+    # resolved [replace conflicting]
+    foo-3.0
+    ''',
+
+    '''
+    # id
+    not_installable
+
+    # installed
+
+    # installable
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    DistributionNotFound
+
+    # resolved [replace conflicting]
+    DistributionNotFound
+    ''',
+
+    '''
+    # id
+    no_matching_version
+
+    # installed
+
+    # installable
+    foo-3.1
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    DistributionNotFound
+
+    # resolved [replace conflicting]
+    DistributionNotFound
+    ''',
+
+    '''
+    # id
+    installable_with_installed_conflict
+
+    # installed
+    foo-3.1
+
+    # installable
+    foo-3.5
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    foo-3.5
+    ''',
+
+    '''
+    # id
+    not_installable_with_installed_conflict
+
+    # installed
+    foo-3.1
+
+    # installable
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    DistributionNotFound
+    ''',
+
+    '''
+    # id
+    installed_with_installed_require
+
+    # installed
+    foo-3.9
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # installable
+
+    # wanted
+    baz
+
+    # resolved
+    foo-3.9
+    baz-0.1
+
+    # resolved [replace conflicting]
+    foo-3.9
+    baz-0.1
+    ''',
+
+    '''
+    # id
+    installed_with_conflicting_installed_require
+
+    # installed
+    foo-5
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # installable
+
+    # wanted
+    baz
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    DistributionNotFound
+    ''',
+
+    '''
+    # id
+    installed_with_installable_conflicting_require
+
+    # installed
+    foo-5
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # installable
+    foo-2.9
+
+    # wanted
+    baz
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    baz-0.1
+    foo-2.9
+    ''',
+
+    '''
+    # id
+    installed_with_installable_require
+
+    # installed
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # installable
+    foo-3.9
+
+    # wanted
+    baz
+
+    # resolved
+    foo-3.9
+    baz-0.1
+
+    # resolved [replace conflicting]
+    foo-3.9
+    baz-0.1
+    ''',
+
+    '''
+    # id
+    installable_with_installed_require
+
+    # installed
+    foo-3.9
+
+    # installable
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # wanted
+    baz
+
+    # resolved
+    foo-3.9
+    baz-0.1
+
+    # resolved [replace conflicting]
+    foo-3.9
+    baz-0.1
+    ''',
+
+    '''
+    # id
+    installable_with_installable_require
+
+    # installed
+
+    # installable
+    foo-3.9
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # wanted
+    baz
+
+    # resolved
+    foo-3.9
+    baz-0.1
+
+    # resolved [replace conflicting]
+    foo-3.9
+    baz-0.1
+    ''',
+
+    '''
+    # id
+    installable_with_conflicting_installable_require
+
+    # installed
+    foo-5
+
+    # installable
+    foo-2.9
+    baz-0.1
+        foo>=2.1,!=3.1,<4
+
+    # wanted
+    baz
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    baz-0.1
+    foo-2.9
+    ''',
+
+    '''
+    # id
+    conflicting_installables
+
+    # installed
+
+    # installable
+    foo-2.9
+    foo-5.0
+
+    # wanted
+    foo>=2.1,!=3.1,<4
+    foo>=4
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    VersionConflict
+    ''',
+
+    '''
+    # id
+    installables_with_conflicting_requires
+
+    # installed
+
+    # installable
+    foo-2.9
+        dep==1.0
+    baz-5.0
+        dep==2.0
+    dep-1.0
+    dep-2.0
+
+    # wanted
+    foo
+    baz
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    VersionConflict
+    ''',
+
+    '''
+    # id
+    installables_with_conflicting_nested_requires
+
+    # installed
+
+    # installable
+    foo-2.9
+        dep1
+    dep1-1.0
+        subdep<1.0
+    baz-5.0
+        dep2
+    dep2-1.0
+        subdep>1.0
+    subdep-0.9
+    subdep-1.1
+
+    # wanted
+    foo
+    baz
+
+    # resolved
+    VersionConflict
+
+    # resolved [replace conflicting]
+    VersionConflict
+    ''',
+)
+def test_working_set_resolve(installed_dists, installable_dists, requirements,
+                             replace_conflicting, resolved_dists_or_exception):
+    ws = pkg_resources.WorkingSet([])
+    list(map(ws.add, installed_dists))
+    resolve_call = lambda: ws.resolve(
+        requirements, installer=FakeInstaller(installable_dists),
+        replace_conflicting=replace_conflicting,
+    )
+    if inspect.isclass(resolved_dists_or_exception):
+        with pytest.raises(resolved_dists_or_exception):
+            resolve_call()
+    else:
+        assert sorted(resolve_call()) == sorted(resolved_dists_or_exception)