Generate: Load generation config when device_map is passed (#25413)

tests/test_modeling_utils.py

@@ -1036,6 +1036,20 @@ class ModelUtilsTest(TestCasePlus):
 
             self.assertEqual(model.__class__.__name__, model_ref.__class__.__name__)
 
+    def test_generation_config_is_loaded_with_model(self):
+        # Note: `joaogante/tiny-random-gpt2-with-generation-config` has a `generation_config.json` containing a dummy
+        # `transformers_version` field set to `foo`. If loading the file fails, this test also fails.
+
+        # 1. Load without further parameters
+        model = AutoModelForCausalLM.from_pretrained("joaogante/tiny-random-gpt2-with-generation-config")
+        self.assertEqual(model.generation_config.transformers_version, "foo")
+
+        # 2. Load with `device_map`
+        model = AutoModelForCausalLM.from_pretrained(
+            "joaogante/tiny-random-gpt2-with-generation-config", device_map="auto"
+        )
+        self.assertEqual(model.generation_config.transformers_version, "foo")
+
 
 @require_torch
 @is_staging_test