[multiple models] skip saving/loading deterministic state_dict keys (#7878)

* make the save_load special key tests common

* handle mbart

* cleaner solution

* fix

* move test_save_load_missing_keys back into fstm for now

* restore

* style

* add marian

* add pegasus

* blenderbot

* revert - no static embed

tests/test_modeling_mbart.py

@@ -5,6 +5,7 @@ from transformers.file_utils import cached_property
 from transformers.testing_utils import require_sentencepiece, require_tokenizers, require_torch, slow, torch_device
 
 from .test_modeling_bart import TOLERANCE, _long_tensor, assert_tensors_close
+from .test_modeling_common import ModelTesterMixin
 
 
 if is_torch_available():
@@ -23,6 +24,37 @@ EN_CODE = 250004
 RO_CODE = 250020
 
 
+@require_torch
+class ModelTester:
+    def __init__(self, parent):
+        self.config = MBartConfig(
+            vocab_size=99,
+            d_model=24,
+            encoder_layers=2,
+            decoder_layers=2,
+            encoder_attention_heads=2,
+            decoder_attention_heads=2,
+            encoder_ffn_dim=32,
+            decoder_ffn_dim=32,
+            max_position_embeddings=48,
+            add_final_layer_norm=True,
+            return_dict=True,
+        )
+
+    def prepare_config_and_inputs_for_common(self):
+        return self.config, {}
+
+
+@require_torch
+class SelectiveCommonTest(unittest.TestCase):
+    all_model_classes = (MBartForConditionalGeneration,) if is_torch_available() else ()
+
+    test_save_load_keys_to_never_save = ModelTesterMixin.test_save_load_keys_to_never_save
+
+    def setUp(self):
+        self.model_tester = ModelTester(self)
+
+
 @require_torch
 @require_sentencepiece
 @require_tokenizers