Improve test and comment

src/_pytest/fixtures.py

@@ -1057,9 +1057,8 @@ def execute(self, request: SubRequest) -> FixtureValue:
         if self.cached_result is not None:
             cache_key = self.cached_result[1]
 
-            # note: `__eq__` is not required to return a bool, and sometimes
-            # doesn't, e.g., numpy arrays (#6497).  Coerce the comparison
-            # into a bool, and if that fails, fall back to an identity check.
+            # Coerce the comparison into a bool (#12600), and if that fails, fall back to an identity check:
+            # `__eq__` is not required to return a bool, and sometimes doesn't, e.g., numpy arrays (#6497).
             try:
                 cache_hit = bool(my_cache_key == cache_key)
             except (ValueError, RuntimeError):

testing/python/fixtures.py

@@ -1568,9 +1568,9 @@ def test_parameterized_fixture_caching(self, pytester: Pytester) -> None:
 
             def pytest_generate_tests(metafunc):
                 if "my_fixture" in metafunc.fixturenames:
-                    param = "d%s" % "1"
-                    print("param id=%d" % id(param), flush=True)
-                    metafunc.parametrize("my_fixture", [param, "d2"], indirect=True)
+                    # Use unique objects for parametrization (as opposed to small strings
+                    # and small integers which are singletons).
+                    metafunc.parametrize("my_fixture", [[1], [2]], indirect=True)
 
             @pytest.fixture(scope='session')
             def my_fixture(request):