Skip tests properly (#31308)

* Skip tests properly

* [test_all]

* Add 'reason' as kwarg for skipTest

* [test_all] Fix up

* [test_all]

tests/models/pegasus/test_modeling_pegasus.py

@@ -592,6 +592,6 @@ class PegasusStandaloneDecoderModelTest(ModelTesterMixin, GenerationTesterMixin,
         config_and_inputs = self.model_tester.prepare_config_and_inputs()
         self.model_tester.create_and_check_decoder_model_attention_mask_past(*config_and_inputs)
 
+    @unittest.skip(reason="Decoder cannot keep gradients")
     def test_retain_grad_hidden_states_attentions(self):
-        # decoder cannot keep gradients
         return

tests/models/pegasus/test_tokenization_pegasus.py

@@ -128,10 +128,6 @@ class PegasusTokenizationTest(TokenizerTesterMixin, unittest.TestCase):
             revision="ba85d0851d708441f91440d509690f1ab6353415",
         )
 
-    # @unittest.skip("We have to use from_slow")
-    # def test_added_tokens_serialization(self):
-    #     pass
-
 
 @require_sentencepiece
 @require_tokenizers
@@ -215,7 +211,3 @@ class BigBirdPegasusTokenizationTest(TokenizerTesterMixin, unittest.TestCase):
             token_ids,
             [182, 117, 142, 587, 4211, 120, 117, 263, 112, 804, 109, 856, 25016, 3137, 464, 109, 26955, 3137, 1],
         )
-
-    # @unittest.skip("We have to use from_slow")
-    # def test_added_tokens_serialization(self):
-    #     pass