Improved messaging for Argument transformation. Fixed #364

graphene/types/argument.py

@@ -28,9 +28,14 @@ class Argument(OrderedType):
         )
 
 
-def to_arguments(args, extra_args):
+def to_arguments(args, extra_args=None):
     from .unmountedtype import UnmountedType
-    extra_args = sorted(extra_args.items(), key=lambda f: f[1])
+    from .field import Field
+    from .inputfield import InputField
+    if extra_args:
+        extra_args = sorted(extra_args.items(), key=lambda f: f[1])
+    else:
+        extra_args = []
     iter_arguments = chain(args.items(), extra_args)
     arguments = OrderedDict()
     for default_name, arg in iter_arguments:
@@ -44,6 +49,13 @@ def to_arguments(args, extra_args):
         if isinstance(arg, UnmountedType):
             arg = arg.Argument()
 
+        if isinstance(arg, (InputField, Field)):
+            raise ValueError('Expected {} to be Argument, but received {}. Try using Argument({}).'.format(
+                default_name,
+                type(arg).__name__,
+                arg.type
+            ))
+
         if not isinstance(arg, Argument):
             raise ValueError('Unknown argument "{}".'.format(default_name))
 

graphene/types/tests/test_argument.py

@@ -1,6 +1,8 @@
 import pytest
 
-from ..argument import Argument
+from ..argument import Argument, to_arguments
+from ..field import Field
+from ..inputfield import InputField
 from ..structures import NonNull
 from ..scalars import String
 
@@ -24,3 +26,38 @@ def test_argument_comparasion():
 def test_argument_required():
     arg = Argument(String, required=True)
     assert arg.type == NonNull(String)
+
+
+def test_to_arguments():
+    args = {
+        'arg_string': Argument(String),
+        'unmounted_arg': String(required=True)
+    }
+
+    my_args = to_arguments(args)
+    assert my_args == {
+        'arg_string': Argument(String),
+        'unmounted_arg': Argument(String, required=True)
+    }
+
+
+def test_to_arguments_raises_if_field():
+    args = {
+        'arg_string': Field(String),
+    }
+
+    with pytest.raises(ValueError) as exc_info:
+        to_arguments(args)
+    
+    assert str(exc_info.value) == 'Expected arg_string to be Argument, but received Field. Try using Argument(String).'
+
+
+def test_to_arguments_raises_if_inputfield():
+    args = {
+        'arg_string': InputField(String),
+    }
+
+    with pytest.raises(ValueError) as exc_info:
+        to_arguments(args)
+    
+    assert str(exc_info.value) == 'Expected arg_string to be Argument, but received InputField. Try using Argument(String).'