fix name issue

Author: TrevorBergeron

bigframes/core/blocks.py

@@ -445,7 +445,7 @@ def reset_index(self, level: LevelsType = None, drop: bool = True) -> Block:
                     if "index" not in self.column_labels and self.index.nlevels <= 1:
                         label = "index"
                     else:
-                        label = f"level_{self.index.names.index(label)}"
+                        label = f"level_{self.index_columns.index(level_id)}"
 
                 if label in self.column_labels:
                     raise ValueError(f"cannot insert {label}, already exists")

tests/unit/test_dataframe_polars.py

@@ -1657,13 +1657,11 @@ def test_reset_index_with_unnamed_index(
     pandas.testing.assert_frame_equal(bf_result, pd_result)
 
 
-def test_reset_index_with_unnamed_multiindex(
-    scalars_df_index,
-    scalars_pandas_df_index,
-):
+def test_reset_index_with_unnamed_multiindex(session):
     bf_df = dataframe.DataFrame(
         ([1, 2, 3], [2, 5, 7]),
         index=pd.MultiIndex.from_tuples([("a", "aa"), ("a", "aa")]),
+        session=session,
     )
     pd_df = pd.DataFrame(
         ([1, 2, 3], [2, 5, 7]),