Fix ModelHubMixin: pass config when __init__ accepts **kwargs (#2058)

* Fix ModelHubMixin: pass config when __init__ accepts **kwargs

* comment

Author: Wauplin

src/huggingface_hub/hub_mixin.py

@@ -270,6 +270,9 @@ def from_pretrained(
 
                 # Forward config to model initialization
                 model_kwargs["config"] = config
+            elif any(param.kind == inspect.Parameter.VAR_KEYWORD for param in init_parameters.values()):
+                # If __init__ accepts **kwargs, let's forward the config as well (as a dict)
+                model_kwargs["config"] = config
 
         instance = cls._from_pretrained(
             model_id=str(model_id),

tests/test_hub_mixin.py

@@ -38,8 +38,11 @@ def _from_pretrained(
         **kwargs,
     ) -> "BaseModel":
         # Little hack but in practice NO-ONE is creating 5 inherited classes for their framework :D
-        if inspect.signature(cls.__init__).parameters.get("config"):
+        init_parameters = inspect.signature(cls.__init__).parameters
+        if init_parameters.get("config"):
             return cls(config=kwargs.get("config"))
+        if init_parameters.get("kwargs"):
+            return cls(**kwargs)
         return cls()
 
 
@@ -68,6 +71,11 @@ def __init__(self, config: Optional[Dict] = None):
         pass
 
 
+class DummyModelWithKwargs(BaseModel, ModelHubMixin):
+    def __init__(self, **kwargs):
+        pass
+
+
 @pytest.mark.usefixtures("fx_cache_dir")
 class HubMixinTest(unittest.TestCase):
     cache_dir: Path
@@ -132,6 +140,34 @@ def test_save_pretrained_with_dict_config(self):
         model.save_pretrained(self.cache_dir, config=CONFIG_AS_DICT)
         self.assert_valid_config_json()
 
+    def test_init_accepts_kwargs_no_config(self):
+        """
+        Test that if `__init__` accepts **kwargs and config file doesn't exist then no 'config' kwargs is passed.
+
+        Regression test. See https://github.com/huggingface/huggingface_hub/pull/2058.
+        """
+        model = DummyModelWithKwargs()
+        model.save_pretrained(self.cache_dir)
+        with patch.object(
+            DummyModelWithKwargs, "_from_pretrained", return_value=DummyModelWithKwargs()
+        ) as from_pretrained_mock:
+            model = DummyModelWithKwargs.from_pretrained(self.cache_dir)
+            assert "config" not in from_pretrained_mock.call_args_list[0].kwargs
+
+    def test_init_accepts_kwargs_with_config(self):
+        """
+        Test that if `__init__` accepts **kwargs and config file exists then the 'config' kwargs is passed.
+
+        Regression test. See https://github.com/huggingface/huggingface_hub/pull/2058.
+        """
+        model = DummyModelWithKwargs()
+        model.save_pretrained(self.cache_dir, config=CONFIG_AS_DICT)
+        with patch.object(
+            DummyModelWithKwargs, "_from_pretrained", return_value=DummyModelWithKwargs()
+        ) as from_pretrained_mock:
+            model = DummyModelWithKwargs.from_pretrained(self.cache_dir)
+            assert "config" in from_pretrained_mock.call_args_list[0].kwargs
+
     def test_save_pretrained_with_push_to_hub(self):
         repo_id = repo_name("save")
         save_directory = self.cache_dir / repo_id