Patch for Py3k with fallback for comparing unsortable sequences in

assertSameElements.

Removed the expected failure and added another test case to confirm that
this patch works for unsortable sequences that are the same (no fail)
and different (fail).

Issue #2578

Lib/test/test_unittest.py

@@ -2392,8 +2392,6 @@ class Test_TestCase(TestCase, TestEquality, TestHashing):
             self.assertRaises(self.failureException, self.assertEqual, a, b,
                               msg='foo')
 
-    # The fact that dictionaries are unorderable breaks this test for them.
-    @unittest.expectedFailure
     def testEquality(self):
         self.assertListEqual([], [])
         self.assertTupleEqual((), ())
@@ -2459,6 +2457,8 @@ class Test_TestCase(TestCase, TestEquality, TestHashing):
         self.assertSameElements([{'a': 1}, {'b': 2}], [{'b': 2}, {'a': 1}])
         self.assertRaises(self.failureException, self.assertSameElements,
                           [[1]], [[2]])
+        self.assertRaises(self.failureException, self.assertSameElements,
+                          [{'a': 1}, {'b': 2}], [{'b': 2}, {'a': 2}])
 
     def testAssertSetEqual(self):
         set1 = set()

Lib/unittest.py

@@ -858,8 +858,12 @@ class TestCase(object):
             # not hashable.
             expected = list(expected_seq)
             actual = list(actual_seq)
+            try:
                 expected.sort()
                 actual.sort()
+            except TypeError:
+                missing, unexpected = _UnorderableListDifference(expected, actual)
+            else:
                 missing, unexpected = _SortedListDifference(expected, actual)
         errors = []
         if missing:
@@ -985,6 +989,22 @@ def _SortedListDifference(expected, actual):
             break
     return missing, unexpected
 
+def _UnorderableListDifference(expected, actual):
+    """Same behavior as _SortedListDifference but
+    for lists of unorderable items (like dicts).
+
+    As it does a linear search per item (remove) it
+    has O(n*n) performance."""
+    missing = []
+    while expected:
+        item = expected.pop()
+        try:
+            actual.remove(item)
+        except ValueError:
+            missing.append(item)
+
+    # anything left in actual is unexpected
+    return missing, actual
 
 class TestSuite(object):
     """A test suite is a composite test consisting of a number of TestCases.