Why when creating instance as a class attribute:
class ModelTestsProducts(TestCase):
# Create example objects in the database
product_category = models.Product_category.objects.create(
name='Spring'
)
product_segment = models.Product_segment.objects.create(
name='PS1',
product_category=self.product_category
)
product_group = models.Product_group.objects.create(
name='PG1',
product_segment=self.product_segment
)
def test_product_category(self):
self.assertEqual(str(self.product_category), self.product_category.name)
def test_product_segment(self):
self.assertEqual(str(self.product_segment), self.product_segment.name)
def test_product_group(self):
self.assertEqual(str(self.product_group), self.product_group.name)
I am getting following error when running test for the 2nd time?
django.db.utils.IntegrityError: duplicate key value violates unique constraint "products_product_category_name_key"
DETAIL: Key (name)=(dadsad) already exists.
When I use setUp method and then create objects insite this setUp method it works fine, but I cant understand why the above method somehow creates every object multiple times and thus fails the unique constraint set in the model.
Is it because django test suite somehow calls this class everytime every test function is run, thus every attribute is assigned multiple times?
But then if I move the object assignment outside the class (in the test file) then I also get this duplicate error, so that would mean whole test file is being called multiple times every time test is being run.
One more thing I use docker to run this Django app and and run django test from docker-compose command.
If you’re using Django’s TestCase, Django will run each test in a separate transaction, that will be rolled back after the test is finished, which means there will be no changes in your database and everything you’ll try to run, will only exist inside your test. This is done to make sure your tests are not affecting each other.
setUp function is also executed inside this transaction and it’s invoked before every test in your test class. But everything you run outside of that function, in your case in the class body, will not be wrapped in such transaction, so it won’t be rolled back between your tests. If this code is reached twice (which may be done under the hood by the test runner), your code will try to create some data in the database that already exists and it will fail.
If you want to do some optimizations of how your tests are being executed, you may use setUpTestData, so your test data is initialized only once for all tests in a single test class. It’ll be wrapped in an outer-shell transaction and will be rolled back after all tests from such test case are done.