TST: Test sorting levels not aligned with index (#25775)

Author: Matias Heikkilä

pandas/tests/frame/test_sorting.py

@@ -1,3 +1,4 @@
+from io import StringIO
 import random
 
 import numpy as np
@@ -227,6 +228,18 @@ def test_stable_descending_multicolumn_sort(self):
                                    kind='mergesort')
         assert_frame_equal(sorted_df, expected)
 
+    def test_sort_multi_index(self):
+        # GH 25775
+        df = DataFrame({'a': [3, 1, 2], 'b': [0, 0, 0],
+                        'c': [0, 1, 2], 'd': list('abc')})
+        result = df.set_index(list('abc')).sort_index(level=list('ba'))
+
+        expected = DataFrame({'a': [1, 2, 3], 'b': [0, 0, 0],
+                            'c': [1, 2, 0], 'd': list('bca')})
+        expected = expected.set_index(list('abc'))
+
+        tm.assert_frame_equal(result, expected)
+
     def test_stable_categorial(self):
         # GH 16793
         df = DataFrame({