2 files changed, 25 insertions, 2 deletions
diff --git a/tests/regressiontests/delete_regress/models.py b/tests/regressiontests/delete_regress/models.py
index 214452c97b..5db253f713 100644
--- a/tests/regressiontests/delete_regress/models.py
+++ b/tests/regressiontests/delete_regress/models.py
@@ -90,4 +90,6 @@ class FooFile(models.Model):
 class FooPhoto(models.Model):
     my_photo = models.ForeignKey(Photo)
 
-
+class FooFileProxy(FooFile):
+    class Meta:
+        proxy = True
diff --git a/tests/regressiontests/delete_regress/tests.py b/tests/regressiontests/delete_regress/tests.py
index 889fba81be..32feae2ded 100644
--- a/tests/regressiontests/delete_regress/tests.py
+++ b/tests/regressiontests/delete_regress/tests.py
@@ -8,7 +8,7 @@ from django.test import TestCase, TransactionTestCase, skipUnlessDBFeature
 
 from .models import (Book, Award, AwardNote, Person, Child, Toy, PlayedWith,
     PlayedWithNote, Email, Researcher, Food, Eaten, Policy, Version, Location,
-    Item, Image, File, Photo, FooFile, FooImage, FooPhoto)
+    Item, Image, File, Photo, FooFile, FooImage, FooPhoto, FooFileProxy)
 
 
 # Can't run this test under SQLite, because you can't
@@ -237,3 +237,24 @@ class ProxyDeleteTest(TestCase):
         # to it.
         self.assertEqual(len(FooFile.objects.all()), 0)
         self.assertEqual(len(FooImage.objects.all()), 0)
+
+
+    def test_delete_proxy_pair(self):
+        """
+        If a pair of proxy models are linked by an FK from one concrete parent
+        to the other, deleting one proxy model cascade-deletes the other, and
+        the deletion happens in the right order (not triggering an
+        IntegrityError on databases unable to defer integrity checks).
+
+        Refs #17918.
+
+        """
+        # Create an Image (proxy of File) and FooFileProxy (proxy of FooFile,
+        # which has an FK to File)
+        image = Image.objects.create()
+        as_file = File.objects.get(pk=image.pk)
+        FooFileProxy.objects.create(my_file=as_file)
+
+        Image.objects.all().delete()
+
+        self.assertEqual(len(FooFileProxy.objects.all()), 0)