Fixed #23289 -- Added mock as a test dependency.

django/test/__init__.py

@@ -16,3 +16,12 @@ __all__ = [
     'skipUnlessDBFeature', 'modify_settings', 'override_settings',
     'override_system_checks'
 ]
+
+# To simplify Django's test suite; not meant as a public API
+try:
+    from unittest import mock  # NOQA
+except ImportError:
+    try:
+        import mock  # NOQA
+    except ImportError:
+        pass

docs/internals/contributing/writing-code/unit-tests.txt

@@ -24,6 +24,11 @@ Running the unit tests
 Quickstart
 ~~~~~~~~~~
 
+If you are on Python < 3.3, you'll first need to install a backport of the
+``unittest.mock`` module that's available in Python 3.3+. See
+:ref:`running-unit-tests-dependencies` for details on installing `mock`_ and
+the other optional test dependencies.
+
 Running the tests requires a Django settings module that defines the
 databases to use. To make it easy to get started, Django provides and uses a
 sample settings module that uses the SQLite database. To run the tests:
@@ -166,6 +171,7 @@ dependencies:
 *  pytz_
 *  setuptools_
 *  memcached_, plus a :ref:`supported Python binding <memcached>`
+*  mock_ (for Python < 3.3)
 *  gettext_ (:ref:`gettext_on_windows`)
 *  selenium_
 *  sqlparse_
@@ -176,7 +182,7 @@ like so:
 
 .. code-block:: bash
 
-   $ pip install -r tests/requirements/py2.txt  # Python 3: py3.txt
+   $ pip install -r tests/requirements/py3.txt  # Python 2: py2.txt
 
 You can also install the database adapter(s) of your choice using
 ``oracle.txt``, ``mysql.txt``, or ``postgres.txt``.
@@ -198,6 +204,7 @@ associated tests will be skipped.
 .. _pytz: https://pypi.python.org/pypi/pytz/
 .. _setuptools: https://pypi.python.org/pypi/setuptools/
 .. _memcached: http://memcached.org/
+.. _mock: https://pypi.python.org/pypi/mock
 .. _gettext: http://www.gnu.org/software/gettext/manual/gettext.html
 .. _selenium: https://pypi.python.org/pypi/selenium
 .. _sqlparse: https://pypi.python.org/pypi/sqlparse

tests/README.rst

 To run the test suite::
 
+    $ cd tests
+    $ pip install -r requirements/py3.txt  # or py2.txt
     $ PYTHONPATH=..:$PYTHONPATH ./runtests.py
 
 For more information about the test suite, see

tests/requirements/base.txt

 bcrypt
 docutils
+# move to py2.txt when dropping Python 3.2
+mock
 numpy
 Pillow
 PyYAML

tests/runtests.py

@@ -374,6 +374,16 @@ if __name__ == "__main__":
         help='Run the Selenium tests as well (if Selenium is installed)')
     options = parser.parse_args()
 
+    # mock is a required dependency
+    try:
+        from django.test import mock  # NOQA
+    except ImportError:
+        print(
+            "Please install test dependencies first: \n"
+            "$ pip install -r requirements/py%s.txt" % sys.version_info.major
+        )
+        sys.exit(1)
+
     # Allow including a trailing slash on app_labels for tab completion convenience
     options.modules = [os.path.normpath(labels) for labels in options.modules]
 

tests/test_runner/tests.py

@@ -10,7 +10,7 @@ from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management import call_command
 from django.db.backends.dummy.base import DatabaseCreation
-from django.test import TestCase, TransactionTestCase, skipUnlessDBFeature
+from django.test import TestCase, TransactionTestCase, mock, skipUnlessDBFeature
 from django.test.runner import DiscoverRunner, dependency_ordered
 from django.test.testcases import connections_support_transactions
 from django.utils import six
@@ -129,13 +129,10 @@ class DependencyOrderingTests(unittest.TestCase):
 
 
 class MockTestRunner(object):
-    invoked = False
-
     def __init__(self, *args, **kwargs):
         pass
 
-    def run_tests(self, test_labels, extra_tests=None, **kwargs):
-        MockTestRunner.invoked = True
+MockTestRunner.run_tests = mock.Mock(return_value=[])
 
 
 class ManageCommandTests(unittest.TestCase):
@@ -143,8 +140,7 @@ class ManageCommandTests(unittest.TestCase):
     def test_custom_test_runner(self):
         call_command('test', 'sites',
                      testrunner='test_runner.tests.MockTestRunner')
-        self.assertTrue(MockTestRunner.invoked,
-                        "The custom test runner has not been invoked")
+        MockTestRunner.run_tests.assert_called_with(('sites',))
 
     def test_bad_test_runner(self):
         with self.assertRaises(AttributeError):