Refactoring test case code for orderedDict and improving 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 maintain dict ordering when :meth:`concat` is called (:issue:`2151`)
+- Bug in :meth:`concat` should maintain dict ordering when :meth:`concat` is called (:issue:`2151`)
 -

pandas/tests/reshape/test_concat.py

@@ -1299,11 +1299,10 @@ def test_concat_with_ordered_dict(self):
         # GH 21510
         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)
+        index = MultiIndex(levels=[['First', 'Another'], [0, 1, 2, 3]],
+                           labels=[[0, 0, 0, 1, 1, 1, 1], [0, 1, 2, 0, 1, 2, 3]])
+        data = list(range(3)) + list(range(4))
+        expected = pd.Series(data,index=index)
         tm.assert_series_equal(result, expected)
 
     def test_crossed_dtypes_weird_corner(self):