adapting bert unitest interface

tests/components_to_test/bert.py

@@ -48,9 +48,21 @@ def get_training_components():
             num_hidden_layers=num_layer,
         )
         print('building BertForSequenceClassification model')
-        model = BertForSequenceClassification(config)
+
+        # adapting huggingface BertForSequenceClassification for single unitest calling interface
+        class ModelAaptor(BertForSequenceClassification):
+
+            def forward(self, input_ids, labels):
+                """
+                inputs: data, label
+                outputs: loss
+                """
+                return super().forward(input_ids=input_ids, labels=labels)[0]
+
+        model = ModelAaptor(config)
         if checkpoint and version.parse(transformers.__version__) >= version.parse("4.11.0"):
             model.gradient_checkpointing_enable()
+
         return model
 
     trainloader = get_bert_data_loader(batch_size=2,