[1.6.x] Fixed #21164 -- Added documentation for issue with test users.

The package renaming restores the older package names (which were also the
documented package names). This doesn't affect test discovery because the
module in question doesn't contain any tests.

Thanks to Carl for the design discussion.

Backport of ddb5385 from master.

django/contrib/auth/tests/test_auth_backends.py

@@ -5,7 +5,7 @@ from django.conf import settings
 from django.contrib.auth.backends import ModelBackend
 from django.contrib.auth.models import User, Group, Permission, AnonymousUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
-from django.contrib.auth.tests.test_custom_user import ExtensionUser, CustomPermissionsUser, CustomUser
+from django.contrib.auth.tests.custom_user import ExtensionUser, CustomPermissionsUser, CustomUser
 from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import ImproperlyConfigured, PermissionDenied
 from django.contrib.auth import authenticate, get_user

django/contrib/auth/tests/test_basic.py

@@ -6,7 +6,7 @@ import locale
 from django.contrib.auth import get_user_model
 from django.contrib.auth.management.commands import createsuperuser
 from django.contrib.auth.models import User, AnonymousUser
-from django.contrib.auth.tests.test_custom_user import CustomUser
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.core.exceptions import ImproperlyConfigured
 from django.core.management import call_command

django/contrib/auth/tests/test_handlers.py

@@ -2,7 +2,7 @@ from __future__ import unicode_literals
 
 from django.contrib.auth.handlers.modwsgi import check_password, groups_for_user
 from django.contrib.auth.models import User, Group
-from django.contrib.auth.tests.test_custom_user import CustomUser
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.test import TransactionTestCase
 from django.test.utils import override_settings

django/contrib/auth/tests/test_management.py

@@ -5,7 +5,7 @@ from django.contrib.auth import models, management
 from django.contrib.auth.management import create_permissions
 from django.contrib.auth.management.commands import changepassword
 from django.contrib.auth.models import User
-from django.contrib.auth.tests.test_custom_user import CustomUser
+from django.contrib.auth.tests.custom_user import CustomUser
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.contrib.contenttypes.models import ContentType
 from django.core.management import call_command

docs/releases/1.6.txt

@@ -442,6 +442,29 @@ but will not be removed from Django until version 1.8.
 
 .. _recommendations in the Python documentation: http://docs.python.org/2/library/doctest.html#unittest-api
 
+Custom User models in tests
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The introduction of the new test runner has also slightly changed the way that
+test models are imported. As a result, any test that overrides ``AUTH_USER_MODEL``
+to test behavior with one of Django's test user models (
+:class:`~django.contrib.auth.tests.custom_user.CustomUser` and
+:class:`~django.contrib.auth.tests.custom_user.ExtensionUser`) must now
+explicitly import the User model in your test module::
+
+    from django.contrib.auth.tests.custom_user import CustomUser
+
+    @override_settings(AUTH_USER_MODEL='auth.CustomUser')
+    class CustomUserFeatureTests(TestCase):
+        def test_something(self):
+            # Test code here ...
+
+This import forces the custom user model to be registered. Without this import,
+the test will be unable to swap in the custom user model, and you will get an
+error reporting::
+
+    ImproperlyConfigured: AUTH_USER_MODEL refers to model 'auth.CustomUser' that has not been installed
+
 Time zone-aware ``day``, ``month``, and ``week_day`` lookups
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

docs/topics/auth/customizing.txt

@@ -893,12 +893,14 @@ that the application works with *any* user model, not just the default User
 model. To assist with this, Django provides two substitute user models that
 can be used in test suites:
 
-* ``django.contrib.auth.tests.custom_user.CustomUser``, a custom user
-  model that uses an ``email`` field as the username, and has a basic
+.. class:: tests.custom_user.CustomUser
+
+  A custom user model that uses an ``email`` field as the username, and has a basic
   admin-compliant permissions setup
 
-* ``django.contrib.auth.tests.custom_user.ExtensionUser``, a custom
-  user model that extends ``django.contrib.auth.models.AbstractUser``,
+.. class:: tests.custom_user.ExtensionUser
+
+  A custom user model that extends ``django.contrib.auth.models.AbstractUser``,
   adding a ``date_of_birth`` field.
 
 You can then use the ``@override_settings`` decorator to make that test run
@@ -907,6 +909,7 @@ would test three possible User models -- the default, plus the two User
 models provided by ``auth`` app::
 
     from django.contrib.auth.tests.utils import skipIfCustomUser
+    from django.contrib.auth.tests.custom_user import CustomUser, ExtensionUser
     from django.test import TestCase
     from django.test.utils import override_settings
 
@@ -927,6 +930,9 @@ models provided by ``auth`` app::
             "Run tests for a simple extension of the built-in User."
             self.assertSomething()
 
+.. versionchanged:: 1.6
+
+    In Django 1.5, it wasn't necessary to explicitly import the test User models.
 
 A full example
 --------------