bpo-43132: Add tests for find_in_strong_cache() bug in _zoneinfo

Co-Authored-By: Paul Ganssle <[email protected]>

Author: ZackerySpytz

Lib/test/test_zoneinfo/test_zoneinfo.py

@@ -400,6 +400,20 @@ def test_time_fixed_offset(self):
                 self.assertEqual(t.utcoffset(), offset.utcoffset)
                 self.assertEqual(t.dst(), offset.dst)
 
+    def test_cache_exception(self):
+        class ComparisonError(Exception):
+            pass
+
+        class Incomparable(str):
+            def __eq__(self, other):
+                raise ComparisonError
+            def __hash__(self):
+                return id(self)
+
+        key = Incomparable("America/Los_Angeles")
+        with self.assertRaises(ComparisonError):
+            self.klass(key)
+
 
 class CZoneInfoTest(ZoneInfoTest):
     module = c_zoneinfo
@@ -1377,6 +1391,33 @@ def test_clear_cache_two_keys(self):
         self.assertIsNot(dub0, dub1)
         self.assertIs(tok0, tok1)
 
+    def test_clear_cache_refleak(self):
+        class ComparisonError(Exception):
+            pass
+
+        class Stringy(str):
+            def __new__(cls, value):
+                rv = super().__new__(cls, value)
+                rv.allow_comparisons = True
+                return rv
+            def __eq__(self, other):
+                if not self.allow_comparisons:
+                    raise ComparisonError
+                return super().__eq__(other)
+            def __hash__(self):
+                return hash(self[:])
+
+        key = Stringy("America/Los_Angeles")
+        self.klass(key)
+        key.allow_comparisons = False
+        try:
+            # Note: This is try/except rather than assertRaises because
+            # there is no guarantee that the key is even still in the cache,
+            # or that the key for the cache is the original `key` object.
+            self.klass.clear_cache(only_keys="America/Los_Angeles")
+        except ComparisonError:
+            pass
+
 
 class CZoneInfoCacheTest(ZoneInfoCacheTest):
     module = c_zoneinfo