GH1366 Relax index setter to align with columns

pandas-stubs/core/frame.pyi

@@ -1760,7 +1760,9 @@ class DataFrame(NDFrame, OpsMixin, _GetItemHack):
     @property
     def index(self) -> Index: ...
     @index.setter
-    def index(self, idx: Index) -> None: ...
+    def index(
+        self, idx: AnyArrayLike | SequenceNotStr[Hashable] | tuple[Hashable, ...]
+    ) -> None: ...
     @property
     def loc(self) -> _LocIndexerFrame[Self]: ...
     @property

pandas-stubs/core/series.pyi

@@ -507,7 +507,9 @@ class Series(IndexOpsMixin[S1], NDFrame):
     @property
     def index(self) -> Index: ...
     @index.setter
-    def index(self, idx: Index) -> None: ...
+    def index(
+        self, idx: AnyArrayLike | SequenceNotStr[Hashable] | tuple[Hashable, ...]
+    ) -> None: ...
     @overload
     def reset_index(
         self,

tests/series/test_series.py

@@ -3982,3 +3982,12 @@ def test_series_explode() -> None:
 
     check(assert_type(s.explode(), pd.Series), pd.Series)
     check(assert_type(s.explode(ignore_index=True), pd.Series), pd.Series)
+
+
+def test_series_index_setter() -> None:
+    """Test Series.index setter property GH1366."""
+    sr = pd.Series(["a", "b"])
+
+    check(assert_type(sr.index, pd.Index), pd.Index)
+    sr.index = [2, 3]
+    check(assert_type(sr.index, pd.Index), pd.Index)

tests/test_frame.py

@@ -4813,3 +4813,12 @@ def test_from_records() -> None:
         ),
         pd.DataFrame,
     )
+
+
+def test_frame_index_setter() -> None:
+    """Test DataFrame.index setter property GH1366."""
+    df = pd.DataFrame(data={"col1": [1, 2], "col2": [3, 4]})
+
+    check(assert_type(df.index, pd.Index), pd.Index)
+    df.index = [2, 3]
+    check(assert_type(df.index, pd.Index), pd.Index)