Raise error when arguments conains only type annotations

graphene/types/argument.py

@@ -75,6 +75,10 @@ def to_arguments(args, extra_args=None):
     from .field import Field
     from .inputfield import InputField
 
+    if type(args) == dict and len(args) == 1 and '__annotations__' in args:
+        raise ValueError(f"Arguments class doesn't have any field but has type annotations. "
+                         f"You probably used ':' instead of '=' in class definition")
+
     if extra_args:
         extra_args = sorted(extra_args.items(), key=lambda f: f[1])
     else:

graphene/types/tests/test_argument.py

@@ -7,6 +7,8 @@
 from ..inputfield import InputField
 from ..scalars import String
 from ..structures import NonNull
+from ..mutation import Mutation
+from graphene.utils.props import props
 
 
 def test_argument():
@@ -74,3 +76,16 @@ def test_argument_with_lazy_partial_type():
     MyType = object()
     arg = Argument(partial(lambda: MyType))
     assert arg.type == MyType
+
+
+def test_arguments_raise_if_type_annotations():
+    class Arguments:
+        id: String()
+
+    with raises(ValueError) as exec_info:
+        to_arguments(props(Arguments))
+
+    assert str(exec_info.value) == (
+        f"Arguments class doesn't have any field but has type annotations. "
+        f"You probably used ':' instead of '=' in class definition"
+    )