Update tests to check sorting

Author: reidy-p

pandas/core/indexes/datetimes.py

@@ -481,6 +481,8 @@ def union(self, other, sort=None):
 
             * False : do not sort the result
 
+            .. versionadded:: 0.25.0
+
         Returns
         -------
         y : Index or DatetimeIndex
@@ -588,7 +590,7 @@ def _fast_union(self, other, sort=None):
             left, right = self, other
         # DTIs are not in the "correct" order and we don't want
         # to sort but want to remove overlaps
-        elif sort is not None:
+        elif sort is False:
             left, right = self, other
             left_start = left[0]
             loc = right.searchsorted(left_start, side='left')

pandas/tests/indexes/datetimes/test_setops.py

@@ -41,27 +41,33 @@ def test_union(self, tz, sort):
         rng1 = pd.date_range('1/1/2000', freq='D', periods=5, tz=tz)
         other1 = pd.date_range('1/6/2000', freq='D', periods=5, tz=tz)
         expected1 = pd.date_range('1/1/2000', freq='D', periods=10, tz=tz)
+        expected1_notsorted = pd.DatetimeIndex(list(other1) + list(rng1))
 
         rng2 = pd.date_range('1/1/2000', freq='D', periods=5, tz=tz)
         other2 = pd.date_range('1/4/2000', freq='D', periods=5, tz=tz)
         expected2 = pd.date_range('1/1/2000', freq='D', periods=8, tz=tz)
+        expected2_notsorted = pd.DatetimeIndex(list(other2) + list(rng2[:3]))
 
         rng3 = pd.date_range('1/1/2000', freq='D', periods=5, tz=tz)
         other3 = pd.DatetimeIndex([], tz=tz)
         expected3 = pd.date_range('1/1/2000', freq='D', periods=5, tz=tz)
+        expected3_notsorted = rng3
 
-        for rng, other, expected in [(rng1, other1, expected1),
-                                     (rng2, other2, expected2),
-                                     (rng3, other3, expected3)]:
+        for rng, other, exp, exp_notsorted in [(rng1, other1, expected1,
+                                                expected1_notsorted),
+                                               (rng2, other2, expected2,
+                                                expected2_notsorted),
+                                               (rng3, other3, expected3,
+                                                expected3_notsorted)]:
 
             result_union = rng.union(other, sort=sort)
-            tm.assert_index_equal(result_union, expected)
+            tm.assert_index_equal(result_union, exp)
 
             result_union = other.union(rng, sort=sort)
             if sort is None:
-                tm.assert_index_equal(result_union, expected)
+                tm.assert_index_equal(result_union, exp)
             else:
-                assert tm.equalContents(result_union, expected)
+                tm.assert_index_equal(result_union, exp_notsorted)
 
     @pytest.mark.parametrize("sort", [None, False])
     def test_union_coverage(self, sort):
@@ -96,7 +102,7 @@ def test_union_bug_1745(self, sort):
                              '2012-05-11 15:27:24.873000',
                              '2012-05-11 15:31:05.350000'])
         if sort is None:
-            exp = DatetimeIndex(sorted(set(list(left)) | set(list(right))))
+            exp = exp.sort_values()
         tm.assert_index_equal(result, exp)
 
     @pytest.mark.parametrize("sort", [None, False])
@@ -336,7 +342,8 @@ def test_union(self, sort):
         if sort is None:
             tm.assert_index_equal(right.union(left, sort=sort), the_union)
         else:
-            assert tm.equalContents(right.union(left, sort=sort), the_union)
+            expected = pd.DatetimeIndex(list(right) + list(left))
+            tm.assert_index_equal(right.union(left, sort=sort), expected)
 
         # overlapping, but different offset
         rng = date_range(START, END, freq=BMonthEnd())
@@ -385,7 +392,8 @@ def test_union_not_cacheable(self, sort):
         if sort is None:
             tm.assert_index_equal(the_union, rng)
         else:
-            assert tm.equalContents(the_union, rng)
+            expected = pd.DatetimeIndex(list(rng[10:]) + list(rng[:10]))
+            tm.assert_index_equal(the_union, expected)
 
         rng1 = rng[10:]
         rng2 = rng[15:35]