fix loc on MultiIndex with slice (#291)

* fix loc on mi with slice

* remove tuple and slice as first part of tuple for loc.getitem

Author: Dr-Irv

pandas-stubs/core/frame.pyi

@@ -136,11 +136,7 @@ class _LocIndexerFrame(_LocIndexer):
         | MaskType
         | list[HashableT]
         | tuple[
-            IndexType
-            | MaskType
-            | slice
-            | list[HashableT]
-            | tuple[str | int | slice, ...],
+            IndexType | MaskType | list[HashableT] | Hashable,
             list[HashableT] | slice | Series[bool] | Callable,
         ],
     ) -> DataFrame: ...

tests/test_frame.py

@@ -1741,3 +1741,12 @@ def test_xs_key() -> None:
     check(
         assert_type(df.xs(0, level="foo"), Union[pd.DataFrame, pd.Series]), pd.DataFrame
     )
+
+
+def test_loc_slice() -> None:
+    # GH 277
+    df1 = pd.DataFrame(
+        {"x": [1, 2, 3, 4]},
+        index=pd.MultiIndex.from_product([[1, 2], ["a", "b"]], names=["num", "let"]),
+    )
+    check(assert_type(df1.loc[1, :], pd.DataFrame), pd.DataFrame)