test multi-column merge

Signed-off-by: Dmitry Chigarev <[email protected]>

modin/core/dataframe/pandas/dataframe/dataframe.py

@@ -3903,6 +3903,7 @@ def _compute_new_widths():
             new_partitions, new_index, new_columns, new_lengths, new_widths, new_dtypes
         )
 
+    @lazy_metadata_decorator(apply_axis="both")
     def _apply_func_to_range_partitioning_broadcast(
         self, right, func, key, new_index=None, new_columns=None, new_dtypes=None
     ):

modin/core/storage_formats/pandas/merge.py

@@ -57,10 +57,10 @@ def range_partitioning_merge(cls, left, right, kwargs):
         on = kwargs.get("on", None)
         if on is not None and not isinstance(on, list):
             on = [on]
-        if on is None or len(on) > 1:
-            raise NotImplementedError(
-                f"Merging on multiple columns is not yet supported by range-partitioning merge: {on=}"
-            )
+        # if on is None or len(on) > 1:
+        #     raise NotImplementedError(
+        #         f"Merging on multiple columns is not yet supported by range-partitioning merge: {on=}"
+        #     )
 
         if any(col not in left.columns or col not in right.columns for col in on):
             raise NotImplementedError(