def test_book_autodelete(self):
note1 = Note(text='text')
note1.save()
note2 = Note(text='text')
note2.save()
book = Book(title='title')
book.save()
book.notes.add(*[note1, note2])
note1.delete()
self.assertTrue(Book.objects.all())
note2.delete()
self.assertFalse(Book.objects.all())
