Expose get_config() on ModelTesters (#12812)

* Expose get_config() on ModelTesters

* Typo

tests/test_modeling_longformer.py

@@ -16,7 +16,7 @@
 
 import unittest
 
-from transformers import is_torch_available
+from transformers import LongformerConfig, is_torch_available
 from transformers.testing_utils import require_sentencepiece, require_tokenizers, require_torch, slow, torch_device
 
 from .test_configuration_common import ConfigTester
@@ -27,7 +27,6 @@ if is_torch_available():
     import torch
 
     from transformers import (
-        LongformerConfig,
         LongformerForMaskedLM,
         LongformerForMultipleChoice,
         LongformerForQuestionAnswering,
@@ -100,7 +99,12 @@ class LongformerModelTester:
             token_labels = ids_tensor([self.batch_size, self.seq_length], self.num_labels)
             choice_labels = ids_tensor([self.batch_size], self.num_choices)
 
-        config = LongformerConfig(
+        config = self.get_config()
+
+        return config, input_ids, token_type_ids, input_mask, sequence_labels, token_labels, choice_labels
+
+    def get_config(self):
+        return LongformerConfig(
             vocab_size=self.vocab_size,
             hidden_size=self.hidden_size,
             num_hidden_layers=self.num_hidden_layers,
@@ -115,8 +119,6 @@ class LongformerModelTester:
             attention_window=self.attention_window,
         )
 
-        return config, input_ids, token_type_ids, input_mask, sequence_labels, token_labels, choice_labels
-
     def create_and_check_attention_mask_determinism(
         self, config, input_ids, token_type_ids, input_mask, sequence_labels, token_labels, choice_labels
     ):