Fix authtoken.TokenProxy error when not installed in Django apps

rest_framework/authtoken/models.py

@@ -2,6 +2,7 @@ import binascii
 import os
 
 from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 
@@ -40,14 +41,31 @@ class Token(models.Model):
         return self.key
 
 
-class TokenProxy(Token):
+if 'rest_framework.authtoken' in settings.INSTALLED_APPS:
-    """
+    class TokenProxy(Token):
-    Proxy mapping pk to user pk for use in admin.
+        """
-    """
+        Proxy mapping pk to user pk for use in admin.
-    @property
+        """
-    def pk(self):
+        @property
-        return self.user.pk
+        def pk(self):
+            return self.user.pk
 
-    class Meta:
+        class Meta:
-        proxy = True
+            proxy = True
-        verbose_name = "token"
+            verbose_name = "token"
+else:
+    def improperly_configured(*args, **kwargs):
+        raise ImproperlyConfigured(
+            '"rest_framework.authtoken" must be in your '
+            'settings.INSTALLED_APPS to use the Token or TokenProxy model.')
+
+    # throw improperly_configured when accessing TokenProxy.objects
+    class Descriptor:
+        def __get__(self, obj, type=None):
+            improperly_configured()
+
+    class TokenProxy:
+        def __init__(self, *args, **kwargs):
+            improperly_configured()
+
+        objects = Descriptor()

tests/test_authtoken.py

@@ -1,10 +1,13 @@
+import importlib
 from io import StringIO
 
 import pytest
 from django.contrib.admin import site
 from django.contrib.auth.models import User
+from django.core.exceptions import ImproperlyConfigured
 from django.core.management import CommandError, call_command
-from django.test import TestCase
+from django.db import models
+from django.test import TestCase, modify_settings
 
 from rest_framework.authtoken.admin import TokenAdmin
 from rest_framework.authtoken.management.commands.drf_create_token import \
@@ -21,6 +24,31 @@ class AuthTokenTests(TestCase):
         self.user = User.objects.create_user(username='test_user')
         self.token = Token.objects.create(key='test token', user=self.user)
 
+    def test_authtoken_can_be_imported_when_not_installed(self):
+        try:
+            import rest_framework.authtoken.models
+            authtoken_models = rest_framework.authtoken.models
+            assert issubclass(authtoken_models.Token, models.Model)
+            assert issubclass(authtoken_models.TokenProxy, models.Model)
+            assert not authtoken_models.Token._meta.abstract
+            assert authtoken_models.TokenProxy._meta.proxy
+
+            with modify_settings(INSTALLED_APPS={
+                    'remove': 'rest_framework.authtoken'}):
+                importlib.reload(rest_framework.authtoken.models)
+                authtoken_models = rest_framework.authtoken.models
+                assert issubclass(authtoken_models.Token, models.Model)
+                assert authtoken_models.Token._meta.abstract
+                with pytest.raises(ImproperlyConfigured):
+                    authtoken_models.TokenProxy()
+                with pytest.raises(ImproperlyConfigured):
+                    authtoken_models.TokenProxy.objects
+
+        finally:
+            # Set the proxy and abstract properties back to the version,
+            # where authtoken is among INSTALLED_APPS.
+            importlib.reload(rest_framework.authtoken.models)
+
     def test_model_admin_displayed_fields(self):
         mock_request = object()
         token_admin = TokenAdmin(self.token, self.site)