Fixed #16905 -- Added extensible checks (nee validation) framework

This is the result of Christopher Medrela's 2013 Summer of Code project.

Thanks also to Preston Holmes, Tim Graham, Anssi Kääriäinen, Florian
Apolloner, and Alex Gaynor for review notes along the way.

Also: Fixes #8579, fixes #3055, fixes #19844.

1 files changed, 20 insertions, 16 deletions

diff --git a/tests/model_validation/tests.py b/tests/model_validation/tests.py
index 225656e4cb..b166f0c072 100644
--- a/tests/model_validation/tests.py
+++ b/tests/model_validation/tests.py
@@ -1,7 +1,5 @@
 from django.core import management
-from django.core.management.validation import (
-    ModelErrorCollection, validate_model_signals
-)
+from django.core.checks import run_checks, Error
 from django.db.models.signals import post_init
 from django.test import TestCase
 from django.utils import six
@@ -24,26 +22,32 @@ class ModelValidationTest(TestCase):
         #       See: https://code.djangoproject.com/ticket/20430
         #   * related_name='+' doesn't clash with another '+'
         #       See: https://code.djangoproject.com/ticket/21375
-        management.call_command("validate", stdout=six.StringIO())
+        management.call_command("check", stdout=six.StringIO())
 
     def test_model_signal(self):
         unresolved_references = post_init.unresolved_references.copy()
         post_init.connect(on_post_init, sender='missing-app.Model')
         post_init.connect(OnPostInit(), sender='missing-app.Model')
-        e = ModelErrorCollection(six.StringIO())
-        validate_model_signals(e)
-        self.assertSetEqual(
-            set(e.errors),
-            {(
-                'model_validation.tests',
+
+        errors = run_checks()
+        expected = [
+            Error(
                 "The `on_post_init` function was connected to the `post_init` "
                 "signal with a lazy reference to the 'missing-app.Model' "
-                "sender, which has not been installed."
-            ), (
-                'model_validation.tests',
+                "sender, which has not been installed.",
+                hint=None,
+                obj='model_validation.tests',
+                id='E014',
+            ),
+            Error(
                 "An instance of the `OnPostInit` class was connected to "
                 "the `post_init` signal with a lazy reference to the "
-                "'missing-app.Model' sender, which has not been installed."
-            )}
-        )
+                "'missing-app.Model' sender, which has not been installed.",
+                hint=None,
+                obj='model_validation.tests',
+                id='E014',
+            )
+        ]
+        self.assertEqual(errors, expected)
+
         post_init.unresolved_references = unresolved_references