django/tests/queries/test_iterator.py

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import datetime
from unittest import mock
from django.db.models.sql.compiler import cursor_iter
from django.test import TestCase
from .models import Article
class QuerySetIteratorTests(TestCase):
itersize_index_in_mock_args = 3
@classmethod
def setUpTestData(cls):
Article.objects.create(name='Article 1', created=datetime.datetime.now())
Article.objects.create(name='Article 2', created=datetime.datetime.now())
def test_iterator_invalid_chunk_size(self):
for size in (0, -1):
with self.subTest(size=size):
with self.assertRaisesMessage(ValueError, 'Chunk size must be strictly positive.'):
Article.objects.iterator(chunk_size=size)
def test_default_iterator_chunk_size(self):
qs = Article.objects.iterator()
with mock.patch('django.db.models.sql.compiler.cursor_iter', side_effect=cursor_iter) as cursor_iter_mock:
next(qs)
self.assertEqual(cursor_iter_mock.call_count, 1)
mock_args, _mock_kwargs = cursor_iter_mock.call_args
self.assertEqual(mock_args[self.itersize_index_in_mock_args], 2000)
def test_iterator_chunk_size(self):
batch_size = 3
qs = Article.objects.iterator(chunk_size=batch_size)
with mock.patch('django.db.models.sql.compiler.cursor_iter', side_effect=cursor_iter) as cursor_iter_mock:
next(qs)
self.assertEqual(cursor_iter_mock.call_count, 1)
mock_args, _mock_kwargs = cursor_iter_mock.call_args
self.assertEqual(mock_args[self.itersize_index_in_mock_args], batch_size)