Add more testing to renaming categories with dicts

Author: alanbato

pandas/tests/test_categorical.py

@@ -994,6 +994,22 @@ def test_rename_categories_dict(self):
                                     inplace=True)
         assert res is None
         tm.assert_index_equal(cat.categories, expected)
+        # Test for dicts of smaller length
+        cat = pd.Categorical(['a', 'b', 'c', 'd'])
+        res = cat.rename_categories({'a': 1, 'c': 3})
+        expected = Index([1, 'b', 3, 'd'])
+        tm.assert_index_equal(res.categories, expected)
+        # Test for dicts with bigger length
+        cat = pd.Categorical(['a', 'b', 'c', 'd'])
+        res = cat.rename_categories({'a': 1, 'b': 2, 'c': 3,
+                                     'd': 4, 'e': 5, 'f': 6})
+        expected = Index([1, 2, 3, 4])
+        tm.assert_index_equal(res.categories, expected)
+        # Test for dicts with no items from old categories
+        cat = pd.Categorical(['a', 'b', 'c', 'd'])
+        res = cat.rename_categories({'f': 1, 'g': 3})
+        expected = Index(['a', 'b', 'c', 'd'])
+        tm.assert_index_equal(res.categories, expected)
 
     @pytest.mark.parametrize('codes, old, new, expected', [
         ([0, 1], ['a', 'b'], ['a', 'b'], [0, 1]),