Check argument types for .normalize_entity (#195)

* Check argument types for .normali_entity

* Fix logic order

* Separate two cases and give more verbose messages

* Added test for additional_variables and copy_variables desired behaviors

* Fix style issue

featuretools/entityset/entityset.py

@@ -800,6 +800,15 @@ def normalize_entity(self, base_entity_id, new_entity_id, index,
         # variable_types = base_entity.variable_types
         additional_variables = additional_variables or []
         copy_variables = copy_variables or []
+
+        if not isinstance(additional_variables, list):
+            raise TypeError("'additional_variables' must be a list, but received type {}"
+                            .format(type(additional_variables)))
+
+        if not isinstance(copy_variables, list):
+            raise TypeError("'copy_variables' must be a list, but received type {}"
+                            .format(type(copy_variables)))
+
         for v in additional_variables + copy_variables:
             if v == index:
                 raise ValueError("Not copying {} as both index and variable".format(v))

featuretools/tests/entityset_tests/test_es.py

@@ -731,6 +731,14 @@ def test_add_link_vars(entityset):
 
 
 def test_normalize_entity(entityset):
+    with pytest.raises(TypeError):
+        entityset.normalize_entity('sessions', 'device_types', 'device_type',
+                                   additional_variables='log')
+
+    with pytest.raises(TypeError):
+        entityset.normalize_entity('sessions', 'device_types', 'device_type',
+                                   copy_variables='log')
+
     entityset.normalize_entity('sessions', 'device_types', 'device_type',
                                additional_variables=['device_name'],
                                make_time_index=False)