Fixed Index.rename() and added test (#936)

* Fixed Index.rename() and added test

* Update tests/test_indexes.py

Co-authored-by: Irv Lustig <[email protected]>

* Update tests/test_indexes.py

Co-authored-by: Irv Lustig <[email protected]>

* Ran precommit

---------

Co-authored-by: Irv Lustig <[email protected]>

Author: devesh-2002

Diff for: pandas-stubs/core/indexes/base.pyi

@@ -292,7 +292,7 @@ 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 = ...): ...
+    def rename(self, name, inplace: bool = ...) -> Self: ...
     @property
     def nlevels(self) -> int: ...
     def sortlevel(self, level=..., ascending: bool = ..., sort_remaining=...): ...

Diff for: tests/test_indexes.py

@@ -113,6 +113,12 @@ def test_str_split() -> None:
     check(assert_type(ind.str.split("-", expand=True), pd.MultiIndex), pd.MultiIndex)
 
 
+def test_index_rename() -> None:
+    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_dropna():
     idx = pd.Index([1, 2])