GH935 Create overload for pd.Index.rename (#1012)

Author: loicdiridollou

pandas-stubs/core/indexes/base.pyi

@@ -292,7 +292,10 @@ class Index(IndexOpsMixin[S1]):
     @names.setter
     def names(self, names: list[_str]): ...
     def set_names(self, names, *, level=..., inplace: bool = ...): ...
-    def rename(self, name, inplace: bool = ...) -> Self: ...
+    @overload
+    def rename(self, name, inplace: Literal[False] = False) -> Self: ...
+    @overload
+    def rename(self, name, inplace: Literal[True]) -> None: ...
     @property
     def nlevels(self) -> int: ...
     def sortlevel(self, level=..., ascending: bool = ..., sort_remaining=...): ...

tests/test_indexes.py

@@ -121,11 +121,20 @@ def test_str_match() -> None:
 
 
 def test_index_rename() -> None:
+    """Test that index rename returns an element of type Index."""
     ind = pd.Index([1, 2, 3], name="foo")
     ind2 = ind.rename("goo")
     check(assert_type(ind2, "pd.Index[int]"), pd.Index, np.integer)
 
 
+def test_index_rename_inplace() -> None:
+    """Test that index rename in-place does not return anything (None)."""
+    ind = pd.Index([1, 2, 3], name="foo")
+    ind2 = ind.rename("goo", inplace=True)
+    check(assert_type(ind2, None), type(None))
+    assert ind2 is None
+
+
 def test_index_dropna():
     idx = pd.Index([1, 2])