Consolidated get_or_create tests.

tests/get_or_create/tests.py

@@ -8,7 +8,8 @@ from django.db import IntegrityError, DatabaseError
 from django.utils.encoding import DjangoUnicodeDecodeError
 from django.test import TestCase, TransactionTestCase
 
-from .models import DefaultPerson, Person, ManualPrimaryKeyTest, Profile, Tag, Thing
+from .models import (DefaultPerson, Person, ManualPrimaryKeyTest, Profile,
+    Tag, Thing, Publisher, Author)
 
 
 class GetOrCreateTests(TestCase):
@@ -237,3 +238,62 @@ class UpdateOrCreateTests(TestCase):
         except IntegrityError:
             formatted_traceback = traceback.format_exc()
             self.assertIn('obj.save', formatted_traceback)
+
+    def test_related(self):
+        p = Publisher.objects.create(name="Acme Publishing")
+        # Create a book through the publisher.
+        book, created = p.books.get_or_create(name="The Book of Ed & Fred")
+        self.assertTrue(created)
+        # The publisher should have one book.
+        self.assertEqual(p.books.count(), 1)
+
+        # Try get_or_create again, this time nothing should be created.
+        book, created = p.books.get_or_create(name="The Book of Ed & Fred")
+        self.assertFalse(created)
+        # And the publisher should still have one book.
+        self.assertEqual(p.books.count(), 1)
+
+        # Add an author to the book.
+        ed, created = book.authors.get_or_create(name="Ed")
+        self.assertTrue(created)
+        # The book should have one author.
+        self.assertEqual(book.authors.count(), 1)
+
+        # Try get_or_create again, this time nothing should be created.
+        ed, created = book.authors.get_or_create(name="Ed")
+        self.assertFalse(created)
+        # And the book should still have one author.
+        self.assertEqual(book.authors.count(), 1)
+
+        # Add a second author to the book.
+        fred, created = book.authors.get_or_create(name="Fred")
+        self.assertTrue(created)
+
+        # The book should have two authors now.
+        self.assertEqual(book.authors.count(), 2)
+
+        # Create an Author not tied to any books.
+        Author.objects.create(name="Ted")
+
+        # There should be three Authors in total. The book object should have two.
+        self.assertEqual(Author.objects.count(), 3)
+        self.assertEqual(book.authors.count(), 2)
+
+        # Try creating a book through an author.
+        _, created = ed.books.get_or_create(name="Ed's Recipes", publisher=p)
+        self.assertTrue(created)
+
+        # Now Ed has two Books, Fred just one.
+        self.assertEqual(ed.books.count(), 2)
+        self.assertEqual(fred.books.count(), 1)
+
+        # Use the publisher's primary key value instead of a model instance.
+        _, created = ed.books.get_or_create(name='The Great Book of Ed', publisher_id=p.id)
+        self.assertTrue(created)
+
+        # Try get_or_create again, this time nothing should be created.
+        _, created = ed.books.get_or_create(name='The Great Book of Ed', publisher_id=p.id)
+        self.assertFalse(created)
+
+        # The publisher should have three books.
+        self.assertEqual(p.books.count(), 3)