Fixed #25415 -- Made DiscoverRunner run system checks.

tests/check_framework/models.py

@@ -1,9 +1,19 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
+from django.core.checks import register
 from django.db import models
 
 
 class SimpleModel(models.Model):
     field = models.IntegerField()
     manager = models.manager.Manager()
+
+
+@register('tests')
+def my_check(app_configs, **kwargs):
+    my_check.did_run = True
+    return []
+
+
+my_check.did_run = False

tests/check_framework/tests.py

@@ -17,7 +17,7 @@ from django.test.utils import (
 from django.utils.encoding import force_text
 from django.utils.six import StringIO
 
-from .models import SimpleModel
+from .models import SimpleModel, my_check
 
 
 class DummyObj(object):
@@ -303,3 +303,8 @@ class CheckFrameworkReservedNamesTests(SimpleTestCase):
             ),
         ]
         self.assertEqual(errors, expected)
+
+
+class ChecksRunDuringTests(SimpleTestCase):
+    def test_registered_check_did_run(self):
+        self.assertTrue(my_check.did_run)