add a test

Author: natmokval

pandas/core/groupby/ops.py

@@ -640,7 +640,6 @@ def _get_splitter(self, data: NDFrame) -> DataSplitter:
     @cache_readonly
     def indices(self) -> dict[Hashable, npt.NDArray[np.intp]]:
         """dict {group name -> group indices}"""
-
         if len(self.groupings) == 1 and isinstance(self.result_index, CategoricalIndex):
             # This shows unused categories in indices GH#38642
             return self.groupings[0].indices

pandas/tests/groupby/test_groupby.py

@@ -2985,3 +2985,10 @@ def test_groupby_agg_namedagg_with_duplicate_columns():
     )
 
     tm.assert_frame_equal(result, expected)
+
+
+def test_groupby_keys_1length_list():
+    # GH#58945
+    df = DataFrame({"x": [10, 20, 30], "y": ["a", "b", "c"]})
+    result = df.groupby(["x"]).groups
+    assert all(isinstance(key, tuple) for key in result.keys())