from django.test import TestCase

from models import Author, Publisher

class GetOrCreateTests(TestCase):

    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)

        # 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)