Raises "KeyError" when argument is invalid on DSL. (#121)

* Raises `KeyError` when argument is invalid.

* styles: apply black formatting

* styles: apply black formatting

Co-authored-by: xzhang2 <[email protected]>
Co-authored-by: Manuel Bojato <[email protected]>

Author: 3 people

gql/dsl.py

@@ -103,6 +103,8 @@ def args(self, **kwargs):
         added_args = []
         for name, value in kwargs.items():
             arg = self.field.args.get(name)
+            if not arg:
+                raise KeyError(f"Argument {name} does not exist in {self.field}.")
             arg_type_serializer = get_arg_serializer(arg.type)
             serialized_value = arg_type_serializer(value)
             added_args.append(

tests/starwars/test_dsl.py

@@ -144,3 +144,10 @@ def test_create_review_mutation_result(ds):
     )
     expected = {"createReview": {"stars": 5, "commentary": "This is a great movie!"}}
     assert result == expected
+
+
+def test_invalid_arg(ds):
+    with pytest.raises(
+        KeyError, match="Argument invalid_arg does not exist in Field: Character."
+    ):
+        ds.query(ds.Query.hero.args(invalid_arg=5).select(ds.Character.name))