Ticket #19822: 19822-1.diff

django/contrib/auth/tests/custom_user.py

@@ -144 +144 @@
         app_label = 'auth'
 
     # the is_active attr is provided by AbstractBaseUser
+
+
+class CustomUserNonUniqueUsername(AbstractBaseUser):
+    username =models.CharField(max_length=30)
+
+    USERNAME_FIELD = 'username'
+
+    class Meta:
+        app_label = 'auth'

django/contrib/auth/tests/management.py

@@ -9 +9 @@
 from django.contrib.auth.tests.utils import skipIfCustomUser
 from django.core.management import call_command
 from django.core.management.base import CommandError
+from django.db.models.loading import get_app
 from django.test import TestCase
 from django.test.utils import override_settings
 from django.utils import six
@@ -170 +171 @@
         self.assertEqual(CustomUser._default_manager.count(), 0)
 
 
+class CustomUserModelValidationTestCase(TestCase):
+    @override_settings(AUTH_USER_MODEL='auth.CustomUserNonUniqueUsername')
+    def test_username_non_unique(self):
+        """
+        A non-unique USERNAME_FIELD should raise a model validation error.
+        """
+        from django.core.management.validation import get_validation_errors
+        new_io = StringIO()
+        get_validation_errors(new_io, get_app('auth'))
+        self.assertIn("The USERNAME_FIELD must be indexed as unique", new_io.getvalue())
+
 class PermissionDuplicationTestCase(TestCase):
 
     def setUp(self):

django/core/management/validation.py

@@ -54 +54 @@
             # Check that the USERNAME FIELD isn't included in REQUIRED_FIELDS.
             if cls.USERNAME_FIELD in cls.REQUIRED_FIELDS:
                 e.add(opts, 'The field named as the USERNAME_FIELD should not be included in REQUIRED_FIELDS on a swappable User model.')
+            if not opts.get_field(cls.USERNAME_FIELD).unique:
+                e.add(opts, 'The USERNAME_FIELD must be indexed as unique (unique=True in the field parameters).')
 
         # Model isn't swapped; do field-specific validation.
         for f in opts.local_fields: