Merge branch 'main' into feature/local-schemesfeature/local-schemes

15 files changed, 1858 insertions, 0 deletions

diff --git a/pkg_resources/tests/__init__.py b/pkg_resources/tests/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/pkg_resources/tests/__init__.py
diff --git a/pkg_resources/tests/data/my-test-package-source/setup.cfg b/pkg_resources/tests/data/my-test-package-source/setup.cfg
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package-source/setup.cfg
diff --git a/pkg_resources/tests/data/my-test-package-source/setup.py b/pkg_resources/tests/data/my-test-package-source/setup.py
new file mode 100644
index 00000000..fe80d28f
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package-source/setup.py
@@ -0,0 +1,6 @@
+import setuptools
+setuptools.setup(
+    name="my-test-package",
+    version="1.0",
+    zip_safe=True,
+)
diff --git a/pkg_resources/tests/data/my-test-package-zip/my-test-package.zip b/pkg_resources/tests/data/my-test-package-zip/my-test-package.zip
new file mode 100644
index 00000000..81f9a017
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package-zip/my-test-package.zip
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO
new file mode 100644
index 00000000..7328e3f7
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/PKG-INFO
@@ -0,0 +1,10 @@
+Metadata-Version: 1.0
+Name: my-test-package
+Version: 1.0
+Summary: UNKNOWN
+Home-page: UNKNOWN
+Author: UNKNOWN
+Author-email: UNKNOWN
+License: UNKNOWN
+Description: UNKNOWN
+Platform: UNKNOWN
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt
new file mode 100644
index 00000000..3c4ee167
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/SOURCES.txt
@@ -0,0 +1,7 @@
+setup.cfg
+setup.py
+my_test_package.egg-info/PKG-INFO
+my_test_package.egg-info/SOURCES.txt
+my_test_package.egg-info/dependency_links.txt
+my_test_package.egg-info/top_level.txt
+my_test_package.egg-info/zip-safe
\ No newline at end of file
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/dependency_links.txt
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/top_level.txt
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_unpacked-egg/my_test_package-1.0-py3.7.egg/EGG-INFO/zip-safe
@@ -0,0 +1 @@
+
diff --git a/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg b/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg
new file mode 100644
index 00000000..5115b895
--- /dev/null
+++ b/pkg_resources/tests/data/my-test-package_zipped-egg/my_test_package-1.0-py3.7.egg
diff --git a/pkg_resources/tests/test_find_distributions.py b/pkg_resources/tests/test_find_distributions.py
new file mode 100644
index 00000000..b01b4827
--- /dev/null
+++ b/pkg_resources/tests/test_find_distributions.py
@@ -0,0 +1,43 @@
+import py
+import pytest
+import pkg_resources
+
+
+TESTS_DATA_DIR = py.path.local(__file__).dirpath('data')
+
+
+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 target_dir
+
+    def test_non_egg_dir_named_egg(self, target_dir):
+        dists = pkg_resources.find_distributions(str(target_dir))
+        assert not list(dists)
+
+    def test_standalone_egg_directory(self, target_dir):
+        (TESTS_DATA_DIR / 'my-test-package_unpacked-egg').copy(target_dir)
+        dists = pkg_resources.find_distributions(str(target_dir))
+        assert [dist.project_name for dist in dists] == ['my-test-package']
+        dists = pkg_resources.find_distributions(str(target_dir), only=True)
+        assert not list(dists)
+
+    def test_zipped_egg(self, target_dir):
+        (TESTS_DATA_DIR / 'my-test-package_zipped-egg').copy(target_dir)
+        dists = pkg_resources.find_distributions(str(target_dir))
+        assert [dist.project_name for dist in dists] == ['my-test-package']
+        dists = pkg_resources.find_distributions(str(target_dir), only=True)
+        assert not list(dists)
+
+    def test_zipped_sdist_one_level_removed(self, target_dir):
+        (TESTS_DATA_DIR / 'my-test-package-zip').copy(target_dir)
+        dists = pkg_resources.find_distributions(
+            str(target_dir / "my-test-package.zip"))
+        assert [dist.project_name for dist in dists] == ['my-test-package']
+        dists = pkg_resources.find_distributions(
+            str(target_dir / "my-test-package.zip"), only=True)
+        assert not list(dists)
diff --git a/pkg_resources/tests/test_markers.py b/pkg_resources/tests/test_markers.py
new file mode 100644
index 00000000..15a3b499
--- /dev/null
+++ b/pkg_resources/tests/test_markers.py
@@ -0,0 +1,8 @@
+import mock
+
+from pkg_resources import evaluate_marker
+
+
+@mock.patch('platform.python_version', return_value='2.7.10')
+def test_ordering(python_version_mock):
+    assert evaluate_marker("python_full_version > '2.7.3'") is True
diff --git a/pkg_resources/tests/test_pkg_resources.py b/pkg_resources/tests/test_pkg_resources.py
new file mode 100644
index 00000000..6518820e
--- /dev/null
+++ b/pkg_resources/tests/test_pkg_resources.py
@@ -0,0 +1,415 @@
+import sys
+import tempfile
+import os
+import zipfile
+import datetime
+import time
+import subprocess
+import stat
+import distutils.dist
+import distutils.command.install_egg_info
+
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+from pkg_resources import (
+    DistInfoDistribution, Distribution, EggInfoDistribution,
+)
+
+import pytest
+
+import pkg_resources
+
+
+def timestamp(dt):
+    """
+    Return a timestamp for a local, naive datetime instance.
+    """
+    try:
+        return dt.timestamp()
+    except AttributeError:
+        # Python 3.2 and earlier
+        return time.mktime(dt.timetuple())
+
+
+class EggRemover(str):
+    def __call__(self):
+        if self in sys.path:
+            sys.path.remove(self)
+        if os.path.exists(self):
+            os.remove(self)
+
+
+class TestZipProvider:
+    finalizers = []
+
+    ref_time = datetime.datetime(2013, 5, 12, 13, 25, 0)
+    "A reference time for a file modification"
+
+    @classmethod
+    def setup_class(cls):
+        "create a zip egg and add it to sys.path"
+        egg = tempfile.NamedTemporaryFile(suffix='.egg', delete=False)
+        zip_egg = zipfile.ZipFile(egg, 'w')
+        zip_info = zipfile.ZipInfo()
+        zip_info.filename = 'mod.py'
+        zip_info.date_time = cls.ref_time.timetuple()
+        zip_egg.writestr(zip_info, 'x = 3\n')
+        zip_info = zipfile.ZipInfo()
+        zip_info.filename = 'data.dat'
+        zip_info.date_time = cls.ref_time.timetuple()
+        zip_egg.writestr(zip_info, 'hello, world!')
+        zip_info = zipfile.ZipInfo()
+        zip_info.filename = 'subdir/mod2.py'
+        zip_info.date_time = cls.ref_time.timetuple()
+        zip_egg.writestr(zip_info, 'x = 6\n')
+        zip_info = zipfile.ZipInfo()
+        zip_info.filename = 'subdir/data2.dat'
+        zip_info.date_time = cls.ref_time.timetuple()
+        zip_egg.writestr(zip_info, 'goodbye, world!')
+        zip_egg.close()
+        egg.close()
+
+        sys.path.append(egg.name)
+        subdir = os.path.join(egg.name, 'subdir')
+        sys.path.append(subdir)
+        cls.finalizers.append(EggRemover(subdir))
+        cls.finalizers.append(EggRemover(egg.name))
+
+    @classmethod
+    def teardown_class(cls):
+        for finalizer in cls.finalizers:
+            finalizer()
+
+    def test_resource_listdir(self):
+        import mod
+        zp = pkg_resources.ZipProvider(mod)
+
+        expected_root = ['data.dat', 'mod.py', 'subdir']
+        assert sorted(zp.resource_listdir('')) == expected_root
+
+        expected_subdir = ['data2.dat', 'mod2.py']
+        assert sorted(zp.resource_listdir('subdir')) == expected_subdir
+        assert sorted(zp.resource_listdir('subdir/')) == expected_subdir
+
+        assert zp.resource_listdir('nonexistent') == []
+        assert zp.resource_listdir('nonexistent/') == []
+
+        import mod2
+        zp2 = pkg_resources.ZipProvider(mod2)
+
+        assert sorted(zp2.resource_listdir('')) == expected_subdir
+
+        assert zp2.resource_listdir('subdir') == []
+        assert zp2.resource_listdir('subdir/') == []
+
+    def test_resource_filename_rewrites_on_change(self):
+        """
+        If a previous call to get_resource_filename has saved the file, but
+        the file has been subsequently mutated with different file of the
+        same size and modification time, it should not be overwritten on a
+        subsequent call to get_resource_filename.
+        """
+        import mod
+        manager = pkg_resources.ResourceManager()
+        zp = pkg_resources.ZipProvider(mod)
+        filename = zp.get_resource_filename(manager, 'data.dat')
+        actual = datetime.datetime.fromtimestamp(os.stat(filename).st_mtime)
+        assert actual == self.ref_time
+        f = open(filename, 'w')
+        f.write('hello, world?')
+        f.close()
+        ts = timestamp(self.ref_time)
+        os.utime(filename, (ts, ts))
+        filename = zp.get_resource_filename(manager, 'data.dat')
+        with open(filename) as f:
+            assert f.read() == 'hello, world!'
+        manager.cleanup_resources()
+
+
+class TestResourceManager:
+    def test_get_cache_path(self):
+        mgr = pkg_resources.ResourceManager()
+        path = mgr.get_cache_path('foo')
+        type_ = str(type(path))
+        message = "Unexpected type from get_cache_path: " + type_
+        assert isinstance(path, str), message
+
+    def test_get_cache_path_race(self, tmpdir):
+        # Patch to os.path.isdir to create a race condition
+        def patched_isdir(dirname, unpatched_isdir=pkg_resources.isdir):
+            patched_isdir.dirnames.append(dirname)
+
+            was_dir = unpatched_isdir(dirname)
+            if not was_dir:
+                os.makedirs(dirname)
+            return was_dir
+
+        patched_isdir.dirnames = []
+
+        # Get a cache path with a "race condition"
+        mgr = pkg_resources.ResourceManager()
+        mgr.set_extraction_path(str(tmpdir))
+
+        archive_name = os.sep.join(('foo', 'bar', 'baz'))
+        with mock.patch.object(pkg_resources, 'isdir', new=patched_isdir):
+            mgr.get_cache_path(archive_name)
+
+        # Because this test relies on the implementation details of this
+        # function, these assertions are a sentinel to ensure that the
+        # test suite will not fail silently if the implementation changes.
+        called_dirnames = patched_isdir.dirnames
+        assert len(called_dirnames) == 2
+        assert called_dirnames[0].split(os.sep)[-2:] == ['foo', 'bar']
+        assert called_dirnames[1].split(os.sep)[-1:] == ['foo']
+
+    """
+    Tests to ensure that pkg_resources runs independently from setuptools.
+    """
+
+    def test_setuptools_not_imported(self):
+        """
+        In a separate Python environment, import pkg_resources and assert
+        that action doesn't cause setuptools to be imported.
+        """
+        lines = (
+            'import pkg_resources',
+            'import sys',
+            (
+                'assert "setuptools" not in sys.modules, '
+                '"setuptools was imported"'
+            ),
+        )
+        cmd = [sys.executable, '-c', '; '.join(lines)]
+        subprocess.check_call(cmd)
+
+
+def make_test_distribution(metadata_path, metadata):
+    """
+    Make a test Distribution object, and return it.
+
+    :param metadata_path: the path to the metadata file that should be
+        created. This should be inside a distribution directory that should
+        also be created. For example, an argument value might end with
+        "<project>.dist-info/METADATA".
+    :param metadata: the desired contents of the metadata file, as bytes.
+    """
+    dist_dir = os.path.dirname(metadata_path)
+    os.mkdir(dist_dir)
+    with open(metadata_path, 'wb') as f:
+        f.write(metadata)
+    dists = list(pkg_resources.distributions_from_metadata(dist_dir))
+    dist, = dists
+
+    return dist
+
+
+def test_get_metadata__bad_utf8(tmpdir):
+    """
+    Test a metadata file with bytes that can't be decoded as utf-8.
+    """
+    filename = 'METADATA'
+    # Convert the tmpdir LocalPath object to a string before joining.
+    metadata_path = os.path.join(str(tmpdir), 'foo.dist-info', filename)
+    # Encode a non-ascii string with the wrong encoding (not utf-8).
+    metadata = 'née'.encode('iso-8859-1')
+    dist = make_test_distribution(metadata_path, metadata=metadata)
+
+    with pytest.raises(UnicodeDecodeError) as excinfo:
+        dist.get_metadata(filename)
+
+    exc = excinfo.value
+    actual = str(exc)
+    expected = (
+        # The error message starts with "'utf-8' codec ..." However, the
+        # spelling of "utf-8" can vary (e.g. "utf8") so we don't include it
+        "codec can't decode byte 0xe9 in position 1: "
+        'invalid continuation byte in METADATA file at path: '
+    )
+    assert expected in actual, 'actual: {}'.format(actual)
+    assert actual.endswith(metadata_path), 'actual: {}'.format(actual)
+
+
+def make_distribution_no_version(tmpdir, basename):
+    """
+    Create a distribution directory with no file containing the version.
+    """
+    dist_dir = tmpdir / basename
+    dist_dir.ensure_dir()
+    # Make the directory non-empty so distributions_from_metadata()
+    # will detect it and yield it.
+    dist_dir.join('temp.txt').ensure()
+
+    if sys.version_info < (3, 6):
+        dist_dir = str(dist_dir)
+
+    dists = list(pkg_resources.distributions_from_metadata(dist_dir))
+    assert len(dists) == 1
+    dist, = dists
+
+    return dist, dist_dir
+
+
+@pytest.mark.parametrize(
+    'suffix, expected_filename, expected_dist_type',
+    [
+        ('egg-info', 'PKG-INFO', EggInfoDistribution),
+        ('dist-info', 'METADATA', DistInfoDistribution),
+    ],
+)
+def test_distribution_version_missing(
+        tmpdir, suffix, expected_filename, expected_dist_type):
+    """
+    Test Distribution.version when the "Version" header is missing.
+    """
+    basename = 'foo.{}'.format(suffix)
+    dist, dist_dir = make_distribution_no_version(tmpdir, basename)
+
+    expected_text = (
+        "Missing 'Version:' header and/or {} file at path: "
+    ).format(expected_filename)
+    metadata_path = os.path.join(dist_dir, expected_filename)
+
+    # Now check the exception raised when the "version" attribute is accessed.
+    with pytest.raises(ValueError) as excinfo:
+        dist.version
+
+    err = str(excinfo.value)
+    # Include a string expression after the assert so the full strings
+    # will be visible for inspection on failure.
+    assert expected_text in err, str((expected_text, err))
+
+    # Also check the args passed to the ValueError.
+    msg, dist = excinfo.value.args
+    assert expected_text in msg
+    # Check that the message portion contains the path.
+    assert metadata_path in msg, str((metadata_path, msg))
+    assert type(dist) == expected_dist_type
+
+
+def test_distribution_version_missing_undetected_path():
+    """
+    Test Distribution.version when the "Version" header is missing and
+    the path can't be detected.
+    """
+    # Create a Distribution object with no metadata argument, which results
+    # in an empty metadata provider.
+    dist = Distribution('/foo')
+    with pytest.raises(ValueError) as excinfo:
+        dist.version
+
+    msg, dist = excinfo.value.args
+    expected = (
+        "Missing 'Version:' header and/or PKG-INFO file at path: "
+        '[could not detect]'
+    )
+    assert msg == expected
+
+
+@pytest.mark.parametrize('only', [False, True])
+def test_dist_info_is_not_dir(tmp_path, only):
+    """Test path containing a file with dist-info extension."""
+    dist_info = tmp_path / 'foobar.dist-info'
+    dist_info.touch()
+    assert not pkg_resources.dist_factory(str(tmp_path), str(dist_info), only)
+
+
+class TestDeepVersionLookupDistutils:
+    @pytest.fixture
+    def env(self, tmpdir):
+        """
+        Create a package environment, similar to a virtualenv,
+        in which packages are installed.
+        """
+
+        class Environment(str):
+            pass
+
+        env = Environment(tmpdir)
+        tmpdir.chmod(stat.S_IRWXU)
+        subs = 'home', 'lib', 'scripts', 'data', 'egg-base'
+        env.paths = dict(
+            (dirname, str(tmpdir / dirname))
+            for dirname in subs
+        )
+        list(map(os.mkdir, env.paths.values()))
+        return env
+
+    def create_foo_pkg(self, env, version):
+        """
+        Create a foo package installed (distutils-style) to env.paths['lib']
+        as version.
+        """
+        ld = "This package has unicode metadata! ❄"
+        attrs = dict(name='foo', version=version, long_description=ld)
+        dist = distutils.dist.Distribution(attrs)
+        iei_cmd = distutils.command.install_egg_info.install_egg_info(dist)
+        iei_cmd.initialize_options()
+        iei_cmd.install_dir = env.paths['lib']
+        iei_cmd.finalize_options()
+        iei_cmd.run()
+
+    def test_version_resolved_from_egg_info(self, env):
+        version = '1.11.0.dev0+2329eae'
+        self.create_foo_pkg(env, version)
+
+        # this requirement parsing will raise a VersionConflict unless the
+        # .egg-info file is parsed (see #419 on BitBucket)
+        req = pkg_resources.Requirement.parse('foo>=1.9')
+        dist = pkg_resources.WorkingSet([env.paths['lib']]).find(req)
+        assert dist.version == version
+
+    @pytest.mark.parametrize(
+        'unnormalized, normalized',
+        [
+            ('foo', 'foo'),
+            ('foo/', 'foo'),
+            ('foo/bar', 'foo/bar'),
+            ('foo/bar/', 'foo/bar'),
+        ],
+    )
+    def test_normalize_path_trailing_sep(self, unnormalized, normalized):
+        """Ensure the trailing slash is cleaned for path comparison.
+
+        See pypa/setuptools#1519.
+        """
+        result_from_unnormalized = pkg_resources.normalize_path(unnormalized)
+        result_from_normalized = pkg_resources.normalize_path(normalized)
+        assert result_from_unnormalized == result_from_normalized
+
+    @pytest.mark.skipif(
+        os.path.normcase('A') != os.path.normcase('a'),
+        reason='Testing case-insensitive filesystems.',
+    )
+    @pytest.mark.parametrize(
+        'unnormalized, normalized',
+        [
+            ('MiXeD/CasE', 'mixed/case'),
+        ],
+    )
+    def test_normalize_path_normcase(self, unnormalized, normalized):
+        """Ensure mixed case is normalized on case-insensitive filesystems.
+        """
+        result_from_unnormalized = pkg_resources.normalize_path(unnormalized)
+        result_from_normalized = pkg_resources.normalize_path(normalized)
+        assert result_from_unnormalized == result_from_normalized
+
+    @pytest.mark.skipif(
+        os.path.sep != '\\',
+        reason='Testing systems using backslashes as path separators.',
+    )
+    @pytest.mark.parametrize(
+        'unnormalized, expected',
+        [
+            ('forward/slash', 'forward\\slash'),
+            ('forward/slash/', 'forward\\slash'),
+            ('backward\\slash\\', 'backward\\slash'),
+        ],
+    )
+    def test_normalize_path_backslash_sep(self, unnormalized, expected):
+        """Ensure path seps are cleaned on backslash path sep systems.
+        """
+        result = pkg_resources.normalize_path(unnormalized)
+        assert result.endswith(expected)
diff --git a/pkg_resources/tests/test_resources.py b/pkg_resources/tests/test_resources.py
new file mode 100644
index 00000000..965a7c00
--- /dev/null
+++ b/pkg_resources/tests/test_resources.py
@@ -0,0 +1,884 @@
+import os
+import sys
+import string
+import platform
+import itertools
+
+import pytest
+from pkg_resources.extern import packaging
+
+import pkg_resources
+from pkg_resources import (
+    parse_requirements, VersionConflict, parse_version,
+    Distribution, EntryPoint, Requirement, safe_version, safe_name,
+    WorkingSet)
+
+
+# from Python 3.6 docs.
+def pairwise(iterable):
+    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
+    a, b = itertools.tee(iterable)
+    next(b, None)
+    return zip(a, b)
+
+
+class Metadata(pkg_resources.EmptyProvider):
+    """Mock object to return metadata as if from an on-disk distribution"""
+
+    def __init__(self, *pairs):
+        self.metadata = dict(pairs)
+
+    def has_metadata(self, name):
+        return name in self.metadata
+
+    def get_metadata(self, name):
+        return self.metadata[name]
+
+    def get_metadata_lines(self, name):
+        return pkg_resources.yield_lines(self.get_metadata(name))
+
+
+dist_from_fn = pkg_resources.Distribution.from_filename
+
+
+class TestDistro:
+    def testCollection(self):
+        # empty path should produce no distributions
+        ad = pkg_resources.Environment([], platform=None, python=None)
+        assert list(ad) == []
+        assert ad['FooPkg'] == []
+        ad.add(dist_from_fn("FooPkg-1.3_1.egg"))
+        ad.add(dist_from_fn("FooPkg-1.4-py2.4-win32.egg"))
+        ad.add(dist_from_fn("FooPkg-1.2-py2.4.egg"))
+
+        # Name is in there now
+        assert ad['FooPkg']
+        # But only 1 package
+        assert list(ad) == ['foopkg']
+
+        # Distributions sort by version
+        expected = ['1.4', '1.3-1', '1.2']
+        assert [dist.version for dist in ad['FooPkg']] == expected
+
+        # Removing a distribution leaves sequence alone
+        ad.remove(ad['FooPkg'][1])
+        assert [dist.version for dist in ad['FooPkg']] == ['1.4', '1.2']
+
+        # And inserting adds them in order
+        ad.add(dist_from_fn("FooPkg-1.9.egg"))
+        assert [dist.version for dist in ad['FooPkg']] == ['1.9', '1.4', '1.2']
+
+        ws = WorkingSet([])
+        foo12 = dist_from_fn("FooPkg-1.2-py2.4.egg")
+        foo14 = dist_from_fn("FooPkg-1.4-py2.4-win32.egg")
+        req, = parse_requirements("FooPkg>=1.3")
+
+        # Nominal case: no distros on path, should yield all applicable
+        assert ad.best_match(req, ws).version == '1.9'
+        # If a matching distro is already installed, should return only that
+        ws.add(foo14)
+        assert ad.best_match(req, ws).version == '1.4'
+
+        # If the first matching distro is unsuitable, it's a version conflict
+        ws = WorkingSet([])
+        ws.add(foo12)
+        ws.add(foo14)
+        with pytest.raises(VersionConflict):
+            ad.best_match(req, ws)
+
+        # If more than one match on the path, the first one takes precedence
+        ws = WorkingSet([])
+        ws.add(foo14)
+        ws.add(foo12)
+        ws.add(foo14)
+        assert ad.best_match(req, ws).version == '1.4'
+
+    def checkFooPkg(self, d):
+        assert d.project_name == "FooPkg"
+        assert d.key == "foopkg"
+        assert d.version == "1.3.post1"
+        assert d.py_version == "2.4"
+        assert d.platform == "win32"
+        assert d.parsed_version == parse_version("1.3-1")
+
+    def testDistroBasics(self):
+        d = Distribution(
+            "/some/path",
+            project_name="FooPkg",
+            version="1.3-1",
+            py_version="2.4",
+            platform="win32",
+        )
+        self.checkFooPkg(d)
+
+        d = Distribution("/some/path")
+        assert d.py_version == '{}.{}'.format(*sys.version_info)
+        assert d.platform is None
+
+    def testDistroParse(self):
+        d = dist_from_fn("FooPkg-1.3.post1-py2.4-win32.egg")
+        self.checkFooPkg(d)
+        d = dist_from_fn("FooPkg-1.3.post1-py2.4-win32.egg-info")
+        self.checkFooPkg(d)
+
+    def testDistroMetadata(self):
+        d = Distribution(
+            "/some/path", project_name="FooPkg",
+            py_version="2.4", platform="win32",
+            metadata=Metadata(
+                ('PKG-INFO', "Metadata-Version: 1.0\nVersion: 1.3-1\n")
+            ),
+        )
+        self.checkFooPkg(d)
+
+    def distRequires(self, txt):
+        return Distribution("/foo", metadata=Metadata(('depends.txt', txt)))
+
+    def checkRequires(self, dist, txt, extras=()):
+        assert list(dist.requires(extras)) == list(parse_requirements(txt))
+
+    def testDistroDependsSimple(self):
+        for v in "Twisted>=1.5", "Twisted>=1.5\nZConfig>=2.0":
+            self.checkRequires(self.distRequires(v), v)
+
+    needs_object_dir = pytest.mark.skipif(
+        not hasattr(object, '__dir__'),
+        reason='object.__dir__ necessary for self.__dir__ implementation',
+    )
+
+    def test_distribution_dir(self):
+        d = pkg_resources.Distribution()
+        dir(d)
+
+    @needs_object_dir
+    def test_distribution_dir_includes_provider_dir(self):
+        d = pkg_resources.Distribution()
+        before = d.__dir__()
+        assert 'test_attr' not in before
+        d._provider.test_attr = None
+        after = d.__dir__()
+        assert len(after) == len(before) + 1
+        assert 'test_attr' in after
+
+    @needs_object_dir
+    def test_distribution_dir_ignores_provider_dir_leading_underscore(self):
+        d = pkg_resources.Distribution()
+        before = d.__dir__()
+        assert '_test_attr' not in before
+        d._provider._test_attr = None
+        after = d.__dir__()
+        assert len(after) == len(before)
+        assert '_test_attr' not in after
+
+    def testResolve(self):
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        # Resolving no requirements -> nothing to install
+        assert list(ws.resolve([], ad)) == []
+        # Request something not in the collection -> DistributionNotFound
+        with pytest.raises(pkg_resources.DistributionNotFound):
+            ws.resolve(parse_requirements("Foo"), ad)
+
+        Foo = Distribution.from_filename(
+            "/foo_dir/Foo-1.2.egg",
+            metadata=Metadata(('depends.txt', "[bar]\nBaz>=2.0"))
+        )
+        ad.add(Foo)
+        ad.add(Distribution.from_filename("Foo-0.9.egg"))
+
+        # Request thing(s) that are available -> list to activate
+        for i in range(3):
+            targets = list(ws.resolve(parse_requirements("Foo"), ad))
+            assert targets == [Foo]
+            list(map(ws.add, targets))
+        with pytest.raises(VersionConflict):
+            ws.resolve(parse_requirements("Foo==0.9"), ad)
+        ws = WorkingSet([])  # reset
+
+        # Request an extra that causes an unresolved dependency for "Baz"
+        with pytest.raises(pkg_resources.DistributionNotFound):
+            ws.resolve(parse_requirements("Foo[bar]"), ad)
+        Baz = Distribution.from_filename(
+            "/foo_dir/Baz-2.1.egg", metadata=Metadata(('depends.txt', "Foo"))
+        )
+        ad.add(Baz)
+
+        # Activation list now includes resolved dependency
+        assert (
+            list(ws.resolve(parse_requirements("Foo[bar]"), ad))
+            == [Foo, Baz]
+        )
+        # Requests for conflicting versions produce VersionConflict
+        with pytest.raises(VersionConflict) as vc:
+            ws.resolve(parse_requirements("Foo==1.2\nFoo!=1.2"), ad)
+
+        msg = 'Foo 0.9 is installed but Foo==1.2 is required'
+        assert vc.value.report() == msg
+
+    def test_environment_marker_evaluation_negative(self):
+        """Environment markers are evaluated at resolution time."""
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        res = ws.resolve(parse_requirements("Foo;python_version<'2'"), ad)
+        assert list(res) == []
+
+    def test_environment_marker_evaluation_positive(self):
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        Foo = Distribution.from_filename("/foo_dir/Foo-1.2.dist-info")
+        ad.add(Foo)
+        res = ws.resolve(parse_requirements("Foo;python_version>='2'"), ad)
+        assert list(res) == [Foo]
+
+    def test_environment_marker_evaluation_called(self):
+        """
+        If one package foo requires bar without any extras,
+        markers should pass for bar without extras.
+        """
+        parent_req, = parse_requirements("foo")
+        req, = parse_requirements("bar;python_version>='2'")
+        req_extras = pkg_resources._ReqExtras({req: parent_req.extras})
+        assert req_extras.markers_pass(req)
+
+        parent_req, = parse_requirements("foo[]")
+        req, = parse_requirements("bar;python_version>='2'")
+        req_extras = pkg_resources._ReqExtras({req: parent_req.extras})
+        assert req_extras.markers_pass(req)
+
+    def test_marker_evaluation_with_extras(self):
+        """Extras are also evaluated as markers at resolution time."""
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        Foo = Distribution.from_filename(
+            "/foo_dir/Foo-1.2.dist-info",
+            metadata=Metadata(("METADATA", "Provides-Extra: baz\n"
+                               "Requires-Dist: quux; extra=='baz'"))
+        )
+        ad.add(Foo)
+        assert list(ws.resolve(parse_requirements("Foo"), ad)) == [Foo]
+        quux = Distribution.from_filename("/foo_dir/quux-1.0.dist-info")
+        ad.add(quux)
+        res = list(ws.resolve(parse_requirements("Foo[baz]"), ad))
+        assert res == [Foo, quux]
+
+    def test_marker_evaluation_with_extras_normlized(self):
+        """Extras are also evaluated as markers at resolution time."""
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        Foo = Distribution.from_filename(
+            "/foo_dir/Foo-1.2.dist-info",
+            metadata=Metadata(("METADATA", "Provides-Extra: baz-lightyear\n"
+                               "Requires-Dist: quux; extra=='baz-lightyear'"))
+        )
+        ad.add(Foo)
+        assert list(ws.resolve(parse_requirements("Foo"), ad)) == [Foo]
+        quux = Distribution.from_filename("/foo_dir/quux-1.0.dist-info")
+        ad.add(quux)
+        res = list(ws.resolve(parse_requirements("Foo[baz-lightyear]"), ad))
+        assert res == [Foo, quux]
+
+    def test_marker_evaluation_with_multiple_extras(self):
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        Foo = Distribution.from_filename(
+            "/foo_dir/Foo-1.2.dist-info",
+            metadata=Metadata(("METADATA", "Provides-Extra: baz\n"
+                               "Requires-Dist: quux; extra=='baz'\n"
+                               "Provides-Extra: bar\n"
+                               "Requires-Dist: fred; extra=='bar'\n"))
+        )
+        ad.add(Foo)
+        quux = Distribution.from_filename("/foo_dir/quux-1.0.dist-info")
+        ad.add(quux)
+        fred = Distribution.from_filename("/foo_dir/fred-0.1.dist-info")
+        ad.add(fred)
+        res = list(ws.resolve(parse_requirements("Foo[baz,bar]"), ad))
+        assert sorted(res) == [fred, quux, Foo]
+
+    def test_marker_evaluation_with_extras_loop(self):
+        ad = pkg_resources.Environment([])
+        ws = WorkingSet([])
+        a = Distribution.from_filename(
+            "/foo_dir/a-0.2.dist-info",
+            metadata=Metadata(("METADATA", "Requires-Dist: c[a]"))
+        )
+        b = Distribution.from_filename(
+            "/foo_dir/b-0.3.dist-info",
+            metadata=Metadata(("METADATA", "Requires-Dist: c[b]"))
+        )
+        c = Distribution.from_filename(
+            "/foo_dir/c-1.0.dist-info",
+            metadata=Metadata(("METADATA", "Provides-Extra: a\n"
+                               "Requires-Dist: b;extra=='a'\n"
+                               "Provides-Extra: b\n"
+                               "Requires-Dist: foo;extra=='b'"))
+        )
+        foo = Distribution.from_filename("/foo_dir/foo-0.1.dist-info")
+        for dist in (a, b, c, foo):
+            ad.add(dist)
+        res = list(ws.resolve(parse_requirements("a"), ad))
+        assert res == [a, c, b, foo]
+
+    def testDistroDependsOptions(self):
+        d = self.distRequires("""
+            Twisted>=1.5
+            [docgen]
+            ZConfig>=2.0
+            docutils>=0.3
+            [fastcgi]
+            fcgiapp>=0.1""")
+        self.checkRequires(d, "Twisted>=1.5")
+        self.checkRequires(
+            d, "Twisted>=1.5 ZConfig>=2.0 docutils>=0.3".split(), ["docgen"]
+        )
+        self.checkRequires(
+            d, "Twisted>=1.5 fcgiapp>=0.1".split(), ["fastcgi"]
+        )
+        self.checkRequires(
+            d, "Twisted>=1.5 ZConfig>=2.0 docutils>=0.3 fcgiapp>=0.1".split(),
+            ["docgen", "fastcgi"]
+        )
+        self.checkRequires(
+            d, "Twisted>=1.5 fcgiapp>=0.1 ZConfig>=2.0 docutils>=0.3".split(),
+            ["fastcgi", "docgen"]
+        )
+        with pytest.raises(pkg_resources.UnknownExtra):
+            d.requires(["foo"])
+
+
+class TestWorkingSet:
+    def test_find_conflicting(self):
+        ws = WorkingSet([])
+        Foo = Distribution.from_filename("/foo_dir/Foo-1.2.egg")
+        ws.add(Foo)
+
+        # create a requirement that conflicts with Foo 1.2
+        req = next(parse_requirements("Foo<1.2"))
+
+        with pytest.raises(VersionConflict) as vc:
+            ws.find(req)
+
+        msg = 'Foo 1.2 is installed but Foo<1.2 is required'
+        assert vc.value.report() == msg
+
+    def test_resolve_conflicts_with_prior(self):
+        """
+        A ContextualVersionConflict should be raised when a requirement
+        conflicts with a prior requirement for a different package.
+        """
+        # Create installation where Foo depends on Baz 1.0 and Bar depends on
+        # Baz 2.0.
+        ws = WorkingSet([])
+        md = Metadata(('depends.txt', "Baz==1.0"))
+        Foo = Distribution.from_filename("/foo_dir/Foo-1.0.egg", metadata=md)
+        ws.add(Foo)
+        md = Metadata(('depends.txt', "Baz==2.0"))
+        Bar = Distribution.from_filename("/foo_dir/Bar-1.0.egg", metadata=md)
+        ws.add(Bar)
+        Baz = Distribution.from_filename("/foo_dir/Baz-1.0.egg")
+        ws.add(Baz)
+        Baz = Distribution.from_filename("/foo_dir/Baz-2.0.egg")
+        ws.add(Baz)
+
+        with pytest.raises(VersionConflict) as vc:
+            ws.resolve(parse_requirements("Foo\nBar\n"))
+
+        msg = "Baz 1.0 is installed but Baz==2.0 is required by "
+        msg += repr(set(['Bar']))
+        assert vc.value.report() == msg
+
+
+class TestEntryPoints:
+    def assertfields(self, ep):
+        assert ep.name == "foo"
+        assert ep.module_name == "pkg_resources.tests.test_resources"
+        assert ep.attrs == ("TestEntryPoints",)
+        assert ep.extras == ("x",)
+        assert ep.load() is TestEntryPoints
+        expect = "foo = pkg_resources.tests.test_resources:TestEntryPoints [x]"
+        assert str(ep) == expect
+
+    def setup_method(self, method):
+        self.dist = Distribution.from_filename(
+            "FooPkg-1.2-py2.4.egg", metadata=Metadata(('requires.txt', '[x]')))
+
+    def testBasics(self):
+        ep = EntryPoint(
+            "foo", "pkg_resources.tests.test_resources", ["TestEntryPoints"],
+            ["x"], self.dist
+        )
+        self.assertfields(ep)
+
+    def testParse(self):
+        s = "foo = pkg_resources.tests.test_resources:TestEntryPoints [x]"
+        ep = EntryPoint.parse(s, self.dist)
+        self.assertfields(ep)
+
+        ep = EntryPoint.parse("bar baz=  spammity[PING]")
+        assert ep.name == "bar baz"
+        assert ep.module_name == "spammity"
+        assert ep.attrs == ()
+        assert ep.extras == ("ping",)
+
+        ep = EntryPoint.parse(" fizzly =  wocka:foo")
+        assert ep.name == "fizzly"
+        assert ep.module_name == "wocka"
+        assert ep.attrs == ("foo",)
+        assert ep.extras == ()
+
+        # plus in the name
+        spec = "html+mako = mako.ext.pygmentplugin:MakoHtmlLexer"
+        ep = EntryPoint.parse(spec)
+        assert ep.name == 'html+mako'
+
+    reject_specs = "foo", "x=a:b:c", "q=x/na", "fez=pish:tush-z", "x=f[a]>2"
+
+    @pytest.mark.parametrize("reject_spec", reject_specs)
+    def test_reject_spec(self, reject_spec):
+        with pytest.raises(ValueError):
+            EntryPoint.parse(reject_spec)
+
+    def test_printable_name(self):
+        """
+        Allow any printable character in the name.
+        """
+        # Create a name with all printable characters; strip the whitespace.
+        name = string.printable.strip()
+        spec = "{name} = module:attr".format(**locals())
+        ep = EntryPoint.parse(spec)
+        assert ep.name == name
+
+    def checkSubMap(self, m):
+        assert len(m) == len(self.submap_expect)
+        for key, ep in self.submap_expect.items():
+            assert m.get(key).name == ep.name
+            assert m.get(key).module_name == ep.module_name
+            assert sorted(m.get(key).attrs) == sorted(ep.attrs)
+            assert sorted(m.get(key).extras) == sorted(ep.extras)
+
+    submap_expect = dict(
+        feature1=EntryPoint('feature1', 'somemodule', ['somefunction']),
+        feature2=EntryPoint(
+            'feature2', 'another.module', ['SomeClass'], ['extra1', 'extra2']),
+        feature3=EntryPoint('feature3', 'this.module', extras=['something'])
+    )
+    submap_str = """
+            # define features for blah blah
+            feature1 = somemodule:somefunction
+            feature2 = another.module:SomeClass [extra1,extra2]
+            feature3 = this.module [something]
+    """
+
+    def testParseList(self):
+        self.checkSubMap(EntryPoint.parse_group("xyz", self.submap_str))
+        with pytest.raises(ValueError):
+            EntryPoint.parse_group("x a", "foo=bar")
+        with pytest.raises(ValueError):
+            EntryPoint.parse_group("x", ["foo=baz", "foo=bar"])
+
+    def testParseMap(self):
+        m = EntryPoint.parse_map({'xyz': self.submap_str})
+        self.checkSubMap(m['xyz'])
+        assert list(m.keys()) == ['xyz']
+        m = EntryPoint.parse_map("[xyz]\n" + self.submap_str)
+        self.checkSubMap(m['xyz'])
+        assert list(m.keys()) == ['xyz']
+        with pytest.raises(ValueError):
+            EntryPoint.parse_map(["[xyz]", "[xyz]"])
+        with pytest.raises(ValueError):
+            EntryPoint.parse_map(self.submap_str)
+
+    def testDeprecationWarnings(self):
+        ep = EntryPoint(
+            "foo", "pkg_resources.tests.test_resources", ["TestEntryPoints"],
+            ["x"]
+        )
+        with pytest.warns(pkg_resources.PkgResourcesDeprecationWarning):
+            ep.load(require=False)
+
+
+class TestRequirements:
+    def testBasics(self):
+        r = Requirement.parse("Twisted>=1.2")
+        assert str(r) == "Twisted>=1.2"
+        assert repr(r) == "Requirement.parse('Twisted>=1.2')"
+        assert r == Requirement("Twisted>=1.2")
+        assert r == Requirement("twisTed>=1.2")
+        assert r != Requirement("Twisted>=2.0")
+        assert r != Requirement("Zope>=1.2")
+        assert r != Requirement("Zope>=3.0")
+        assert r != Requirement("Twisted[extras]>=1.2")
+
+    def testOrdering(self):
+        r1 = Requirement("Twisted==1.2c1,>=1.2")
+        r2 = Requirement("Twisted>=1.2,==1.2c1")
+        assert r1 == r2
+        assert str(r1) == str(r2)
+        assert str(r2) == "Twisted==1.2c1,>=1.2"
+        assert (
+            Requirement("Twisted")
+            !=
+            Requirement("Twisted @ https://localhost/twisted.zip")
+        )
+
+    def testBasicContains(self):
+        r = Requirement("Twisted>=1.2")
+        foo_dist = Distribution.from_filename("FooPkg-1.3_1.egg")
+        twist11 = Distribution.from_filename("Twisted-1.1.egg")
+        twist12 = Distribution.from_filename("Twisted-1.2.egg")
+        assert parse_version('1.2') in r
+        assert parse_version('1.1') not in r
+        assert '1.2' in r
+        assert '1.1' not in r
+        assert foo_dist not in r
+        assert twist11 not in r
+        assert twist12 in r
+
+    def testOptionsAndHashing(self):
+        r1 = Requirement.parse("Twisted[foo,bar]>=1.2")
+        r2 = Requirement.parse("Twisted[bar,FOO]>=1.2")
+        assert r1 == r2
+        assert set(r1.extras) == set(("foo", "bar"))
+        assert set(r2.extras) == set(("foo", "bar"))
+        assert hash(r1) == hash(r2)
+        assert (
+            hash(r1)
+            ==
+            hash((
+                "twisted",
+                None,
+                packaging.specifiers.SpecifierSet(">=1.2"),
+                frozenset(["foo", "bar"]),
+                None
+            ))
+        )
+        assert (
+            hash(Requirement.parse("Twisted @ https://localhost/twisted.zip"))
+            ==
+            hash((
+                "twisted",
+                "https://localhost/twisted.zip",
+                packaging.specifiers.SpecifierSet(),
+                frozenset(),
+                None
+            ))
+        )
+
+    def testVersionEquality(self):
+        r1 = Requirement.parse("foo==0.3a2")
+        r2 = Requirement.parse("foo!=0.3a4")
+        d = Distribution.from_filename
+
+        assert d("foo-0.3a4.egg") not in r1
+        assert d("foo-0.3a1.egg") not in r1
+        assert d("foo-0.3a4.egg") not in r2
+
+        assert d("foo-0.3a2.egg") in r1
+        assert d("foo-0.3a2.egg") in r2
+        assert d("foo-0.3a3.egg") in r2
+        assert d("foo-0.3a5.egg") in r2
+
+    def testSetuptoolsProjectName(self):
+        """
+        The setuptools project should implement the setuptools package.
+        """
+
+        assert (
+            Requirement.parse('setuptools').project_name == 'setuptools')
+        # setuptools 0.7 and higher means setuptools.
+        assert (
+            Requirement.parse('setuptools == 0.7').project_name
+            == 'setuptools'
+        )
+        assert (
+            Requirement.parse('setuptools == 0.7a1').project_name
+            == 'setuptools'
+        )
+        assert (
+            Requirement.parse('setuptools >= 0.7').project_name
+            == 'setuptools'
+        )
+
+
+class TestParsing:
+    def testEmptyParse(self):
+        assert list(parse_requirements('')) == []
+
+    def testYielding(self):
+        for inp, out in [
+            ([], []), ('x', ['x']), ([[]], []), (' x\n y', ['x', 'y']),
+            (['x\n\n', 'y'], ['x', 'y']),
+        ]:
+            assert list(pkg_resources.yield_lines(inp)) == out
+
+    def testSplitting(self):
+        sample = """
+                    x
+                    [Y]
+                    z
+
+                    a
+                    [b ]
+                    # foo
+                    c
+                    [ d]
+                    [q]
+                    v
+                    """
+        assert (
+            list(pkg_resources.split_sections(sample))
+            ==
+            [
+                (None, ["x"]),
+                ("Y", ["z", "a"]),
+                ("b", ["c"]),
+                ("d", []),
+                ("q", ["v"]),
+            ]
+        )
+        with pytest.raises(ValueError):
+            list(pkg_resources.split_sections("[foo"))
+
+    def testSafeName(self):
+        assert safe_name("adns-python") == "adns-python"
+        assert safe_name("WSGI Utils") == "WSGI-Utils"
+        assert safe_name("WSGI  Utils") == "WSGI-Utils"
+        assert safe_name("Money$$$Maker") == "Money-Maker"
+        assert safe_name("peak.web") != "peak-web"
+
+    def testSafeVersion(self):
+        assert safe_version("1.2-1") == "1.2.post1"
+        assert safe_version("1.2 alpha") == "1.2.alpha"
+        assert safe_version("2.3.4 20050521") == "2.3.4.20050521"
+        assert safe_version("Money$$$Maker") == "Money-Maker"
+        assert safe_version("peak.web") == "peak.web"
+
+    def testSimpleRequirements(self):
+        assert (
+            list(parse_requirements('Twis-Ted>=1.2-1'))
+            ==
+            [Requirement('Twis-Ted>=1.2-1')]
+        )
+        assert (
+            list(parse_requirements('Twisted >=1.2, \\ # more\n<2.0'))
+            ==
+            [Requirement('Twisted>=1.2,<2.0')]
+        )
+        assert (
+            Requirement.parse("FooBar==1.99a3")
+            ==
+            Requirement("FooBar==1.99a3")
+        )
+        with pytest.raises(ValueError):
+            Requirement.parse(">=2.3")
+        with pytest.raises(ValueError):
+            Requirement.parse("x\\")
+        with pytest.raises(ValueError):
+            Requirement.parse("x==2 q")
+        with pytest.raises(ValueError):
+            Requirement.parse("X==1\nY==2")
+        with pytest.raises(ValueError):
+            Requirement.parse("#")
+
+    def test_requirements_with_markers(self):
+        assert (
+            Requirement.parse("foobar;os_name=='a'")
+            ==
+            Requirement.parse("foobar;os_name=='a'")
+        )
+        assert (
+            Requirement.parse("name==1.1;python_version=='2.7'")
+            !=
+            Requirement.parse("name==1.1;python_version=='3.6'")
+        )
+        assert (
+            Requirement.parse("name==1.0;python_version=='2.7'")
+            !=
+            Requirement.parse("name==1.2;python_version=='2.7'")
+        )
+        assert (
+            Requirement.parse("name[foo]==1.0;python_version=='3.6'")
+            !=
+            Requirement.parse("name[foo,bar]==1.0;python_version=='3.6'")
+        )
+
+    def test_local_version(self):
+        req, = parse_requirements('foo==1.0.org1')
+
+    def test_spaces_between_multiple_versions(self):
+        req, = parse_requirements('foo>=1.0, <3')
+        req, = parse_requirements('foo >= 1.0, < 3')
+
+    @pytest.mark.parametrize(
+        ['lower', 'upper'],
+        [
+            ('1.2-rc1', '1.2rc1'),
+            ('0.4', '0.4.0'),
+            ('0.4.0.0', '0.4.0'),
+            ('0.4.0-0', '0.4-0'),
+            ('0post1', '0.0post1'),
+            ('0pre1', '0.0c1'),
+            ('0.0.0preview1', '0c1'),
+            ('0.0c1', '0-rc1'),
+            ('1.2a1', '1.2.a.1'),
+            ('1.2.a', '1.2a'),
+        ],
+    )
+    def testVersionEquality(self, lower, upper):
+        assert parse_version(lower) == parse_version(upper)
+
+    torture = """
+        0.80.1-3 0.80.1-2 0.80.1-1 0.79.9999+0.80.0pre4-1
+        0.79.9999+0.80.0pre2-3 0.79.9999+0.80.0pre2-2
+        0.77.2-1 0.77.1-1 0.77.0-1
+        """
+
+    @pytest.mark.parametrize(
+        ['lower', 'upper'],
+        [
+            ('2.1', '2.1.1'),
+            ('2a1', '2b0'),
+            ('2a1', '2.1'),
+            ('2.3a1', '2.3'),
+            ('2.1-1', '2.1-2'),
+            ('2.1-1', '2.1.1'),
+            ('2.1', '2.1post4'),
+            ('2.1a0-20040501', '2.1'),
+            ('1.1', '02.1'),
+            ('3.2', '3.2.post0'),
+            ('3.2post1', '3.2post2'),
+            ('0.4', '4.0'),
+            ('0.0.4', '0.4.0'),
+            ('0post1', '0.4post1'),
+            ('2.1.0-rc1', '2.1.0'),
+            ('2.1dev', '2.1a0'),
+        ] + list(pairwise(reversed(torture.split()))),
+    )
+    def testVersionOrdering(self, lower, upper):
+        assert parse_version(lower) < parse_version(upper)
+
+    def testVersionHashable(self):
+        """
+        Ensure that our versions stay hashable even though we've subclassed
+        them and added some shim code to them.
+        """
+        assert (
+            hash(parse_version("1.0"))
+            ==
+            hash(parse_version("1.0"))
+        )
+
+
+class TestNamespaces:
+
+    ns_str = "__import__('pkg_resources').declare_namespace(__name__)\n"
+
+    @pytest.fixture
+    def symlinked_tmpdir(self, tmpdir):
+        """
+        Where available, return the tempdir as a symlink,
+        which as revealed in #231 is more fragile than
+        a natural tempdir.
+        """
+        if not hasattr(os, 'symlink'):
+            yield str(tmpdir)
+            return
+
+        link_name = str(tmpdir) + '-linked'
+        os.symlink(str(tmpdir), link_name)
+        try:
+            yield type(tmpdir)(link_name)
+        finally:
+            os.unlink(link_name)
+
+    @pytest.fixture(autouse=True)
+    def patched_path(self, tmpdir):
+        """
+        Patch sys.path to include the 'site-pkgs' dir. Also
+        restore pkg_resources._namespace_packages to its
+        former state.
+        """
+        saved_ns_pkgs = pkg_resources._namespace_packages.copy()
+        saved_sys_path = sys.path[:]
+        site_pkgs = tmpdir.mkdir('site-pkgs')
+        sys.path.append(str(site_pkgs))
+        try:
+            yield
+        finally:
+            pkg_resources._namespace_packages = saved_ns_pkgs
+            sys.path = saved_sys_path
+
+    issue591 = pytest.mark.xfail(platform.system() == 'Windows', reason="#591")
+
+    @issue591
+    def test_two_levels_deep(self, symlinked_tmpdir):
+        """
+        Test nested namespace packages
+        Create namespace packages in the following tree :
+            site-packages-1/pkg1/pkg2
+            site-packages-2/pkg1/pkg2
+        Check both are in the _namespace_packages dict and that their __path__
+        is correct
+        """
+        real_tmpdir = symlinked_tmpdir.realpath()
+        tmpdir = symlinked_tmpdir
+        sys.path.append(str(tmpdir / 'site-pkgs2'))
+        site_dirs = tmpdir / 'site-pkgs', tmpdir / 'site-pkgs2'
+        for site in site_dirs:
+            pkg1 = site / 'pkg1'
+            pkg2 = pkg1 / 'pkg2'
+            pkg2.ensure_dir()
+            (pkg1 / '__init__.py').write_text(self.ns_str, encoding='utf-8')
+            (pkg2 / '__init__.py').write_text(self.ns_str, encoding='utf-8')
+        import pkg1
+        assert "pkg1" in pkg_resources._namespace_packages
+        # attempt to import pkg2 from site-pkgs2
+        import pkg1.pkg2
+        # check the _namespace_packages dict
+        assert "pkg1.pkg2" in pkg_resources._namespace_packages
+        assert pkg_resources._namespace_packages["pkg1"] == ["pkg1.pkg2"]
+        # check the __path__ attribute contains both paths
+        expected = [
+            str(real_tmpdir / "site-pkgs" / "pkg1" / "pkg2"),
+            str(real_tmpdir / "site-pkgs2" / "pkg1" / "pkg2"),
+        ]
+        assert pkg1.pkg2.__path__ == expected
+
+    @issue591
+    def test_path_order(self, symlinked_tmpdir):
+        """
+        Test that if multiple versions of the same namespace package subpackage
+        are on different sys.path entries, that only the one earliest on
+        sys.path is imported, and that the namespace package's __path__ is in
+        the correct order.
+
+        Regression test for https://github.com/pypa/setuptools/issues/207
+        """
+
+        tmpdir = symlinked_tmpdir
+        site_dirs = (
+            tmpdir / "site-pkgs",
+            tmpdir / "site-pkgs2",
+            tmpdir / "site-pkgs3",
+        )
+
+        vers_str = "__version__ = %r"
+
+        for number, site in enumerate(site_dirs, 1):
+            if number > 1:
+                sys.path.append(str(site))
+            nspkg = site / 'nspkg'
+            subpkg = nspkg / 'subpkg'
+            subpkg.ensure_dir()
+            (nspkg / '__init__.py').write_text(self.ns_str, encoding='utf-8')
+            (subpkg / '__init__.py').write_text(
+                vers_str % number, encoding='utf-8')
+
+        import nspkg.subpkg
+        import nspkg
+        expected = [
+            str(site.realpath() / 'nspkg')
+            for site in site_dirs
+        ]
+        assert nspkg.__path__ == expected
+        assert nspkg.subpkg.__version__ == 1
diff --git a/pkg_resources/tests/test_working_set.py b/pkg_resources/tests/test_working_set.py
new file mode 100644
index 00000000..db13c714
--- /dev/null
+++ b/pkg_resources/tests/test_working_set.py
@@ -0,0 +1,482 @@
+import inspect
+import re
+import textwrap
+import functools
+
+import pytest
+
+import pkg_resources
+
+from .test_resources import Metadata
+
+
+def strip_comments(s):
+    return '\n'.join(
+        line for line in s.split('\n')
+        if line.strip() and not line.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(r'\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:
+
+    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(r'\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 = functools.partial(
+        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)