Issue #21112: Fix regression in unittest.expectedFailure on subclasses.

Patch from Berker Peksag.

Lib/unittest/test/test_skipping.py

@@ -120,6 +120,39 @@ class Test_TestSkipping(unittest.TestCase):
         self.assertEqual(result.expectedFailures[0][0], test)
         self.assertTrue(result.wasSuccessful())
 
+    def test_expected_failure_with_wrapped_class(self):
+        @unittest.expectedFailure
+        class Foo(unittest.TestCase):
+            def test_1(self):
+                self.assertTrue(False)
+
+        events = []
+        result = LoggingResult(events)
+        test = Foo("test_1")
+        test.run(result)
+        self.assertEqual(events,
+                         ['startTest', 'addExpectedFailure', 'stopTest'])
+        self.assertEqual(result.expectedFailures[0][0], test)
+        self.assertTrue(result.wasSuccessful())
+
+    def test_expected_failure_with_wrapped_subclass(self):
+        class Foo(unittest.TestCase):
+            def test_1(self):
+                self.assertTrue(False)
+
+        @unittest.expectedFailure
+        class Bar(Foo):
+            pass
+
+        events = []
+        result = LoggingResult(events)
+        test = Bar("test_1")
+        test.run(result)
+        self.assertEqual(events,
+                         ['startTest', 'addExpectedFailure', 'stopTest'])
+        self.assertEqual(result.expectedFailures[0][0], test)
+        self.assertTrue(result.wasSuccessful())
+
     def test_expected_failure_subtests(self):
         # A failure in any subtest counts as the expected failure of the
         # whole test.