Improving test case for orderedDict and whatsnew info. #21510

Author: SaturninoMateus

doc/source/whatsnew/v0.23.2.txt

@@ -83,5 +83,5 @@ Bug Fixes
 **Other**
 
 - Bug in :meth:`Series.nlargest` for signed and unsigned integer dtypes when the minimum value is present (:issue:`21426`)
-- Bug in :class:`_Concatenator` should not sort Ordered Dictionaries (:issue:`21510`)
+- Bug in :class:`_Concatenator` should maintain dict ordering when :meth:`concat` is called (:issue:`2151`)
 -

pandas/tests/reshape/test_concat.py

@@ -1297,13 +1297,14 @@ def test_concat_rename_index(self):
 
     def test_concat_with_ordered_dict(self):
         # GH 21510
-        ps = pd.concat(OrderedDict([('First', pd.Series(range(3))),
-                                    ('Another', pd.Series(range(4)))]))
-        ps_list = list(ps.keys())
-        exp_list = [('First', 0), ('First', 1), ('First', 2),
-                    ('Another', 0), ('Another', 1),
-                    ('Another', 2), ('Another', 3)]
-        assert ps_list == exp_list
+        result = pd.concat(OrderedDict([('First', pd.Series(range(3))),
+                                        ('Another', pd.Series(range(4)))]))
+        a = pd.Series(range(3), range(3))
+        b = pd.Series(range(4), range(4))
+        a.index = pd.MultiIndex.from_tuples([('First', v) for v in a.index])
+        b.index = pd.MultiIndex.from_tuples([('Another', v) for v in b.index])
+        expected = a.append(b)
+        tm.assert_series_equal(result, expected)
 
     def test_crossed_dtypes_weird_corner(self):
         columns = ['A', 'B', 'C', 'D']