Add test for proper TF input signatures (#24320)

* Add test for proper input signatures

* No more signature pruning

* Test the dummy inputs are valid too

* fine-tine -> fine-tune

* Fix indent in test_dataset_conversion

tests/utils/test_modeling_tf_core.py

@@ -217,18 +217,17 @@ class TFCoreModelTesterMixin:
         for model_class in self.all_model_classes:
             class_inputs_dict = self._prepare_for_class(inputs_dict, model_class)
             model = model_class(config)
-            class_sig = model._prune_signature(model.input_signature)
             num_out = len(model(class_inputs_dict))
 
             for key in list(class_inputs_dict.keys()):
                 # Remove keys not in the serving signature, as the SavedModel will not be compiled to deal with them
-                if key not in class_sig:
+                if key not in model.input_signature:
                     del class_inputs_dict[key]
                 # Check it's a tensor, in case the inputs dict has some bools in it too
                 elif isinstance(class_inputs_dict[key], tf.Tensor) and class_inputs_dict[key].dtype.is_integer:
                     class_inputs_dict[key] = tf.cast(class_inputs_dict[key], tf.int32)
 
-            if set(class_inputs_dict.keys()) != set(class_sig.keys()):
+            if set(class_inputs_dict.keys()) != set(model.input_signature.keys()):
                 continue  # Some models have inputs that the preparation functions don't create, we skip those
 
             with tempfile.TemporaryDirectory() as tmpdirname: