From 865bc7178364145f901c5ac5a5b8eb722cc0a646 Mon Sep 17 00:00:00 2001
From: Daniel Pyrathon <pirosb3@gmail.com>
Date: Tue, 8 Jul 2014 11:24:08 +0200
Subject: [PATCH] Added a unit test to ensure models cannot be ordered by a M2M
 field.

---
 tests/invalid_models_tests/test_models.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tests/invalid_models_tests/test_models.py b/tests/invalid_models_tests/test_models.py
index 6bce3f9a26..3bfccdb2a9 100644
--- a/tests/invalid_models_tests/test_models.py
+++ b/tests/invalid_models_tests/test_models.py
@@ -540,6 +540,27 @@ class OtherModelTests(IsolatedModelsTestCase):
         ]
         self.assertEqual(errors, expected)
 
+    def test_non_valid(self):
+        class RelationModel(models.Model):
+            pass
+
+        class Model(models.Model):
+            relation = models.ManyToManyField(RelationModel)
+
+            class Meta:
+                ordering = ['relation']
+
+        errors = Model.check()
+        expected = [
+            Error(
+                "'ordering' refers to the non-existent field 'relation'.",
+                hint=None,
+                obj=Model,
+                id='models.E015',
+            ),
+        ]
+        self.assertEqual(errors, expected)
+
     def test_ordering_pointing_to_missing_field(self):
         class Model(models.Model):
             class Meta: