Fix cloudformation NoValue parsing to not add attribute. Closes #870

moto/cloudformation/parsing.py

@@ -158,7 +158,11 @@ def clean_json(resource_json, resources_map):
 
         cleaned_json = {}
         for key, value in resource_json.items():
-            cleaned_json[key] = clean_json(value, resources_map)
+            cleaned_val = clean_json(value, resources_map)
+            if cleaned_val is None:
+                # If we didn't find anything, don't add this attribute
+                continue
+            cleaned_json[key] = cleaned_val
         return cleaned_json
     elif isinstance(resource_json, list):
         return [clean_json(val, resources_map) for val in resource_json]

tests/test_cloudformation/test_cloudformation_stack_integration.py

@@ -382,6 +382,7 @@ def test_stack_elb_integration_with_update():
                             "Protocol": "HTTP",
                         }
                     ],
+                    "Policies": {"Ref" : "AWS::NoValue"},
                 }
             },
         },