Add tests.

Author: gcaria

pandas/core/frame.py

@@ -5614,7 +5614,7 @@ def reset_index(
         col_level: Hashable = 0,
         col_fill: Hashable = "",
         names: Hashable | Sequence[Hashable] = None,
-    ) -> Optional[DataFrame]:
+    ) -> DataFrame | None:
         """
         Reset the index, or a level of it.
 

pandas/tests/frame/methods/test_reset_index.py

@@ -183,6 +183,27 @@ def test_reset_index_name(self):
         assert return_value is None
         assert df.index.name is None
 
+    def test_reset_index_rename(self, float_frame):
+        # index
+        rdf = float_frame.reset_index(names="new_name")
+        exp = Series(float_frame.index.values, name="new_name")
+        tm.assert_series_equal(rdf["new_name"], exp)
+
+        # multiindex
+        stacked = float_frame.stack()[::2]
+        stacked = DataFrame({"foo": stacked, "bar": stacked})
+
+        names = ["first", "second"]
+        stacked.index.names = names
+        deleveled = stacked.reset_index()
+        deleveled2 = stacked.reset_index(names=["new_first", "new_second"])
+        tm.assert_series_equal(
+            deleveled["first"], deleveled2["new_first"], check_names=False
+        )
+        tm.assert_series_equal(
+            deleveled["second"], deleveled2["new_second"], check_names=False
+        )
+
     def test_reset_index_level(self):
         df = DataFrame([[1, 2, 3, 4], [5, 6, 7, 8]], columns=["A", "B", "C", "D"])