Update test_multi.py

pandas/tests/indexes/test_multi.py

@@ -165,16 +165,20 @@ def test_set_name_methods(self):
         assert res is None
         assert ind.names == new_names2
 
-    def test_multiindex_set_names(self):
+    @pytest.mark.parametrize('inplace_flg,expected_out', [
+        (True, pd.MultiIndex(levels=[[0, 1]],
+                             labels=[[0, 1]],
+                             names=['first'])),
+        (False, pd.MultiIndex(levels=[[0, 1]],
+                              labels=[[0, 1]]))])
+    def test_multiindex_set_names(self, inplace_flg, expected_out):
         # GH 21149
-        '''Ensure that .set_names for MultiIndex with
+        """ Ensure that .set_names for MultiIndex with
             nlevels == 1 does not raise any errors
-        '''
+        """
         result = pd.MultiIndex.from_product([[0, 1]])
-        result.set_names('first', level=0, inplace=True)
-        expected = pd.MultiIndex(levels=[[0, 1]],
-                                 labels=[[0, 1]],
-                                 names=['first'])
+        result.set_names('first', level=0, inplace=inplace_flg)
+        expected = expected_out
         tm.assert_index_equal(result, expected)
 
     def test_set_levels_labels_directly(self):