Merge pull request #552 from python/debt/revert-prefer-greater-version

Revert "Prefer the greater metadata directory when a path supplies several"

Author: jaraco

importlib_metadata/__init__.py

@@ -922,22 +922,14 @@ def __init__(self, path: FastPath):
         From the children in the path, calculate early all of the
         children that appear to represent metadata (infos) or legacy
         metadata (eggs).
-
-        Children are considered in reverse lexicographic order, so when
-        a path supplies more than one metadata directory for a
-        distribution, as an interrupted or unclean upgrade may leave
-        behind, the greater one is found first
-        (python/cpython#100666). Because the order is lexicographic on
-        the directory name and not on the parsed version, it only
-        approximates a preference for the newer version.
         """
 
         base = os.path.basename(path.root).lower()
         base_is_egg = base.endswith(".egg")
         self.infos = FreezableDefaultDict(list)
         self.eggs = FreezableDefaultDict(list)
 
-        for child in sorted(path.children(), key=str.lower, reverse=True):
+        for child in path.children():
             low = child.lower()
             if low.endswith((".dist-info", ".egg-info")):
                 # rpartition is faster than splitext and suitable for this purpose.

newsfragments/+revert-prefer-greater-version.feature.rst

@@ -0,0 +1,6 @@
+Reverted the preference for the greater metadata directory added in v9.1.0.
+The ordering was lexicographic on the directory name and not on the parsed
+version, so it only approximated a preference for the newer version. Where a
+path supplies more than one metadata directory for a distribution, discovery
+once again reports them in the order the path supplies
+(python/cpython#100666).

tests/test_main.py

@@ -208,76 +208,6 @@ def test_missing_required_metadata(self):
             unversioned.version
 
 
-class MultipleVersionsTests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
-    """
-    An unclean upgrade can leave more than one metadata directory for a
-    distribution in one path. Prefer the greater one.
-
-    Ref python/cpython#100666.
-    """
-
-    # Deliberately not in version order; the preference follows the
-    # lexicographic ordering of the directory names, which only
-    # approximates the ordering of the versions they name.
-    versions = '1.12.1', '1.13.1', '1.9.0', '2.0.0'
-    expected = '2.0.0', '1.9.0', '1.13.1', '1.12.1'
-
-    @staticmethod
-    def make_pkg(name, version, files=None):
-        """
-        Create metadata for a dist-info package at the indicated version.
-        """
-        return {
-            f'{name}-{version}.dist-info': (
-                {'METADATA': f'Name: {name}\nVersion: {version}\n'}
-                if files is None
-                else files
-            ),
-        }
-
-    def build_versions(self, *versions):
-        for ver in versions:
-            fixtures.build_files(self.make_pkg('foo', ver), self.site_dir)
-
-    def test_greater_version_preferred(self):
-        """
-        Retrieving by name resolves to the greater version.
-        """
-        self.build_versions(*self.versions)
-        assert version('foo') == self.expected[0]
-
-    def test_discovery_order(self):
-        """
-        Preferring one version doesn't hide the others from discovery,
-        which reports them greatest first.
-        """
-        self.build_versions(*self.versions)
-        found = tuple(dist.version for dist in Distribution.discover(name='foo'))
-        assert found == self.expected
-
-    def test_greater_version_preferred_in_eggs(self):
-        """
-        Legacy egg-info metadata gets the same preference.
-        """
-        fixtures.build_files(
-            {
-                f'foo-{ver}.egg-info': {'PKG-INFO': f'Name: foo\nVersion: {ver}\n'}
-                for ver in self.versions
-            },
-            self.site_dir,
-        )
-        assert version('foo') == self.expected[0]
-
-    def test_validity_preferred_to_version(self):
-        """
-        A valid dist is still preferred to an invalid one of a greater
-        version, the condition that prompted the report.
-        """
-        self.build_versions('1.12.1')
-        fixtures.build_files(self.make_pkg('foo', '2.0.0', files={}), self.site_dir)
-        assert version('foo') == '1.12.1'
-
-
 class NonASCIITests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
     @staticmethod
     def pkg_with_non_ascii_description(site_dir):