Added backwards compatibility for assertRaisesMessage callable_obj param.

This was broken in c2bc1cef (refs #23763).

django/test/testcases.py

@@ -589,6 +589,10 @@ class SimpleTestCase(unittest.TestCase):
             args: Function to be called and extra positional args.
             kwargs: Extra kwargs.
         """
+        # callable_obj was a documented kwarg in Django 1.8 and older.
+        callable_obj = kwargs.pop('callable_obj', None)
+        if callable_obj:
+            args = (callable_obj,) + args
         return six.assertRaisesRegex(self, expected_exception,
                 re.escape(expected_message), *args, **kwargs)
 

tests/test_utils/tests.py

@@ -752,6 +752,12 @@ class AssertRaisesMsgTest(SimpleTestCase):
             raise ValueError("[.*x+]y?")
         self.assertRaisesMessage(ValueError, "[.*x+]y?", func1)
 
+    def test_callable_obj_param(self):
+        # callable_obj was a documented kwarg in Django 1.8 and older.
+        def func1():
+            raise ValueError("[.*x+]y?")
+        self.assertRaisesMessage(ValueError, "[.*x+]y?", callable_obj=func1)
+
 
 class AssertFieldOutputTests(SimpleTestCase):