[1.5.x] Add assertJSONEqual method to TestCase

Backport of 089d9ca from master

django/test/testcases.py

@@ -407,6 +407,18 @@ def assertInHTML(self, needle, haystack, count = None, msg_prefix=''):
             self.assertTrue(real_count != 0,
                 msg_prefix + "Couldn't find '%s' in response" % needle)
 
+    def assertJSONEqual(self, raw, expected_data, msg=None):
+        try:
+            data = json.loads(raw)
+        except ValueError:
+            self.fail("First argument is not valid JSON: %r" % raw)
+        if isinstance(expected_data, six.string_types):
+            try:
+                expected_data = json.loads(expected_data)
+            except ValueError:
+                self.fail("Second argument is not valid JSON: %r" % expected_data)
+        self.assertEqual(data, expected_data, msg=msg)
+
     def assertXMLEqual(self, xml1, xml2, msg=None):
         """
         Asserts that two XML snippets are semantically the same.