Define a __hash__ on the packaging.version.Version subclasses

In Python 3.x a subclass will not inherent the __hash__ method from
the parent classes if the subclass defines a __eq__ method. This
means that without defining our own __hash__ the SetuptoolsVersion
classes are unhashable.

2 files changed, 13 insertions, 0 deletions

diff --git a/pkg_resources.py b/pkg_resources.py
index 5df5a3e6..4c7924b7 100644
--- a/pkg_resources.py
+++ b/pkg_resources.py
@@ -82,6 +82,9 @@ packaging = setuptools._vendor.packaging
 
 class _SetuptoolsVersionMixin(object):
 
+    def __hash__(self):
+        return super(_SetuptoolsVersionMixin, self).__hash__()
+
     def __lt__(self, other):
         if isinstance(other, tuple):
             return tuple(self) < other
diff --git a/setuptools/tests/test_resources.py b/setuptools/tests/test_resources.py
index 13f80aa4..1902fb2c 100644
--- a/setuptools/tests/test_resources.py
+++ b/setuptools/tests/test_resources.py
@@ -528,6 +528,16 @@ class ParseTests(TestCase):
         self.assertTrue(parse_version("3.0") != tuple(parse_version("2.0")))
         self.assertFalse(parse_version("3.0") != tuple(parse_version("3.0")))
 
+    def testVersionHashable(self):
+        """
+        Ensure that our versions stay hashable even though we've subclassed
+        them and added some shim code to them.
+        """
+        self.assertEqual(
+            hash(parse_version("1.0")),
+            hash(parse_version("1.0")),
+        )
+
 
 class ScriptHeaderTests(TestCase):
     non_ascii_exe = '/Users/José/bin/python'