FIX-1708: Don't sort indexes in Series functions with level parameter (#1830)

Signed-off-by: Anatoly Myachev <anatoly.myachev@intel.com>

Author: anmyachev

modin/pandas/base.py

@@ -125,7 +125,7 @@ def _handle_level_agg(self, axis, level, op, **kwargs):
             level: The level of the axis to apply the operation on
             op: String representation of the operation to be performed on the level
         """
-        return getattr(self.groupby(level=level, axis=axis), op)(**kwargs)
+        return getattr(self.groupby(level=level, axis=axis, sort=False), op)(**kwargs)
 
     def _validate_other(
         self,

modin/pandas/test/test_series.py

@@ -28,6 +28,7 @@
     df_equals,
     arg_keys,
     name_contains,
+    test_data,
     test_data_values,
     test_data_keys,
     test_string_data_values,
@@ -1802,6 +1803,24 @@ def test_last():
     df_equals(modin_series.last("20D"), pandas_series.last("20D"))
 
 
+def test_index_order():
+    # see #1708 for details
+    s_modin, s_pandas = create_test_series(test_data["dense_nan_data"])
+    rows_number = len(s_modin.index)
+    level_0 = np.random.choice([x for x in range(10)], rows_number)
+    level_1 = np.random.choice([x for x in range(10)], rows_number)
+    index = pandas.MultiIndex.from_arrays([level_0, level_1])
+
+    s_modin.index = index
+    s_pandas.index = index
+
+    for func in ["all", "any", "mad"]:
+        df_equals(
+            getattr(s_modin, func)(level=0).index,
+            getattr(s_pandas, func)(level=0).index,
+        )
+
+
 @pytest.mark.parametrize("data", test_data_values, ids=test_data_keys)
 def test_last_valid_index(data):
     modin_series, pandas_series = create_test_series(data)