Generate: save generation config with the models' .save_pretrained() (#21264)

tests/test_modeling_flax_common.py

@@ -36,7 +36,7 @@ from transformers.testing_utils import (
     require_flax,
     torch_device,
 )
-from transformers.utils import logging
+from transformers.utils import CONFIG_NAME, GENERATION_CONFIG_NAME, logging
 from transformers.utils.generic import ModelOutput
 
 
@@ -395,6 +395,13 @@ class FlaxModelTesterMixin:
                 # verify that normal save_pretrained works as expected
                 with tempfile.TemporaryDirectory() as tmpdirname:
                     model.save_pretrained(tmpdirname)
+
+                    # the config file (and the generation config file, if it can generate) should be saved
+                    self.assertTrue(os.path.exists(os.path.join(tmpdirname, CONFIG_NAME)))
+                    self.assertEqual(
+                        model.can_generate(), os.path.exists(os.path.join(tmpdirname, GENERATION_CONFIG_NAME))
+                    )
+
                     model_loaded = model_class.from_pretrained(tmpdirname)
 
                 outputs_loaded = model_loaded(**prepared_inputs_dict).to_tuple()