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224 lines
8.4 KiB
Python
224 lines
8.4 KiB
Python
from django.db.models import Prefetch, prefetch_related_objects
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from django.test import TestCase
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from .models import Author, Book, House, Reader, Room
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class PrefetchRelatedObjectsTests(TestCase):
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"""
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Since prefetch_related_objects() is just the inner part of
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prefetch_related(), only do basic tests to ensure its API hasn't changed.
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"""
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@classmethod
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def setUpTestData(cls):
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cls.book1 = Book.objects.create(title="Poems")
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cls.book2 = Book.objects.create(title="Jane Eyre")
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cls.book3 = Book.objects.create(title="Wuthering Heights")
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cls.book4 = Book.objects.create(title="Sense and Sensibility")
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cls.author1 = Author.objects.create(name="Charlotte", first_book=cls.book1)
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cls.author2 = Author.objects.create(name="Anne", first_book=cls.book1)
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cls.author3 = Author.objects.create(name="Emily", first_book=cls.book1)
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cls.author4 = Author.objects.create(name="Jane", first_book=cls.book4)
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cls.book1.authors.add(cls.author1, cls.author2, cls.author3)
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cls.book2.authors.add(cls.author1)
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cls.book3.authors.add(cls.author3)
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cls.book4.authors.add(cls.author4)
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cls.reader1 = Reader.objects.create(name="Amy")
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cls.reader2 = Reader.objects.create(name="Belinda")
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cls.reader1.books_read.add(cls.book1, cls.book4)
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cls.reader2.books_read.add(cls.book2, cls.book4)
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cls.house1 = House.objects.create(name="b1", address="1")
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cls.house2 = House.objects.create(name="b2", address="2")
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cls.room1 = Room.objects.create(name="a1", house=cls.house1)
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cls.room2 = Room.objects.create(name="a2", house=cls.house2)
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cls.house1.main_room = cls.room1
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cls.house1.save()
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cls.house2.main_room = cls.room2
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cls.house2.save()
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def test_unknown(self):
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book1 = Book.objects.get(id=self.book1.id)
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with self.assertRaises(AttributeError):
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prefetch_related_objects([book1], "unknown_attribute")
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def test_m2m_forward(self):
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book1 = Book.objects.get(id=self.book1.id)
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with self.assertNumQueries(1):
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prefetch_related_objects([book1], "authors")
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with self.assertNumQueries(0):
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self.assertCountEqual(
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book1.authors.all(), [self.author1, self.author2, self.author3]
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)
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def test_m2m_reverse(self):
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author1 = Author.objects.get(id=self.author1.id)
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with self.assertNumQueries(1):
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prefetch_related_objects([author1], "books")
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with self.assertNumQueries(0):
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self.assertCountEqual(author1.books.all(), [self.book1, self.book2])
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def test_foreignkey_forward(self):
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authors = list(Author.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(authors, "first_book")
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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with self.assertNumQueries(0):
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[author.first_book for author in authors]
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authors = list(Author.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(
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authors,
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Prefetch("first_book", queryset=Book.objects.order_by("-title")),
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)
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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def test_foreignkey_reverse(self):
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books = list(Book.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(books, "first_time_authors")
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self.assertIn("ORDER BY", ctx.captured_queries[0]["sql"])
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with self.assertNumQueries(0):
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[list(book.first_time_authors.all()) for book in books]
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books = list(Book.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(
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books,
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Prefetch(
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"first_time_authors",
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queryset=Author.objects.order_by("-name"),
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),
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)
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self.assertIn("ORDER BY", ctx.captured_queries[0]["sql"])
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def test_one_to_one_forward(self):
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houses = list(House.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(houses, "main_room")
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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with self.assertNumQueries(0):
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[house.main_room for house in houses]
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houses = list(House.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(
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houses,
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Prefetch("main_room", queryset=Room.objects.order_by("-name")),
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)
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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def test_one_to_one_reverse(self):
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rooms = list(Room.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(rooms, "main_room_of")
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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with self.assertNumQueries(0):
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[room.main_room_of for room in rooms]
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rooms = list(Room.objects.all())
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with self.assertNumQueries(1) as ctx:
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prefetch_related_objects(
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rooms,
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Prefetch("main_room_of", queryset=House.objects.order_by("-name")),
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)
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self.assertNotIn("ORDER BY", ctx.captured_queries[0]["sql"])
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def test_m2m_then_m2m(self):
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"""A m2m can be followed through another m2m."""
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authors = list(Author.objects.all())
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with self.assertNumQueries(2):
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prefetch_related_objects(authors, "books__read_by")
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with self.assertNumQueries(0):
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self.assertEqual(
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[
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[[str(r) for r in b.read_by.all()] for b in a.books.all()]
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for a in authors
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],
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[
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[["Amy"], ["Belinda"]], # Charlotte - Poems, Jane Eyre
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[["Amy"]], # Anne - Poems
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[["Amy"], []], # Emily - Poems, Wuthering Heights
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[["Amy", "Belinda"]], # Jane - Sense and Sense
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],
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)
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def test_prefetch_object(self):
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book1 = Book.objects.get(id=self.book1.id)
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with self.assertNumQueries(1):
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prefetch_related_objects([book1], Prefetch("authors"))
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with self.assertNumQueries(0):
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self.assertCountEqual(
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book1.authors.all(), [self.author1, self.author2, self.author3]
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)
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def test_prefetch_object_twice(self):
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book1 = Book.objects.get(id=self.book1.id)
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book2 = Book.objects.get(id=self.book2.id)
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with self.assertNumQueries(1):
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prefetch_related_objects([book1], Prefetch("authors"))
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with self.assertNumQueries(1):
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prefetch_related_objects([book1, book2], Prefetch("authors"))
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with self.assertNumQueries(0):
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self.assertCountEqual(book2.authors.all(), [self.author1])
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def test_prefetch_object_to_attr(self):
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book1 = Book.objects.get(id=self.book1.id)
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with self.assertNumQueries(1):
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prefetch_related_objects(
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[book1], Prefetch("authors", to_attr="the_authors")
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)
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with self.assertNumQueries(0):
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self.assertCountEqual(
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book1.the_authors, [self.author1, self.author2, self.author3]
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)
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def test_prefetch_object_to_attr_twice(self):
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book1 = Book.objects.get(id=self.book1.id)
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book2 = Book.objects.get(id=self.book2.id)
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with self.assertNumQueries(1):
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prefetch_related_objects(
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[book1],
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Prefetch("authors", to_attr="the_authors"),
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)
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with self.assertNumQueries(1):
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prefetch_related_objects(
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[book1, book2],
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Prefetch("authors", to_attr="the_authors"),
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)
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with self.assertNumQueries(0):
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self.assertCountEqual(book2.the_authors, [self.author1])
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def test_prefetch_queryset(self):
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book1 = Book.objects.get(id=self.book1.id)
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with self.assertNumQueries(1):
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prefetch_related_objects(
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[book1],
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Prefetch(
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"authors",
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queryset=Author.objects.filter(
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id__in=[self.author1.id, self.author2.id]
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),
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),
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)
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with self.assertNumQueries(0):
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self.assertCountEqual(book1.authors.all(), [self.author1, self.author2])
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