#28400: TransactionTestCase will truncate data created from data migration
-------------------------------------+-------------------------------------
Reporter: Jared | Owner: nobody
Mackey |
Type: Bug | Status: new
Component: Testing | Version: 1.11
framework | Keywords: tests,data-
Severity: Normal | migrations
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Data migrations that create data in the database do not persist after
running tests that inherit from `TransactionTestCase`. The first test that
runs on the database works as expected but subsequent tests do not.
Here is an example migration:
{{{
def add_group_permissions(apps, schema_editor):
for app_config in apps.get_app_configs():
app_config.models_module = True
create_permissions(app_config, verbosity=0)
app_config.models_module = None
Group = apps.get_model('auth', 'Group')
Permission = apps.get_model('auth', 'Permission')
group, _ = Group.objects.get_or_create(name='demo_group')
group.permissions.clear()
permission = Permission.objects.get(codename='existing_permission')
group.permissions.add(permission)
class Migration(migrations.Migration):
dependencies = [ ]
operations = [
migrations.RunPython(add_group_permissions,
reverse_code=migrations.RunPython.noop),
migrations.RunPython(lambda apps, schema_editor:
ContentType.objects.clear_cache()), # hack to get the ContentType cache
to clear
]
}}}
Here is a test case that will prove that the second test to run will fail
with `django.contrib.auth.models.DoesNotExist: Group matching query does
not exist.`
{{{
class TestGroupsExist(TransactionTestCase):
""" One of these tests will fail. Which one depends on which one the
test runner runs first. The second one to run will fail. """
def test_group_exists_1(self):
self.assertIsNotNone(Group.objects.get_by_natural_key('demo_group'))
def test_group_exists_2(self):
self.assertIsNotNone(Group.objects.get_by_natural_key('demo_group'))
}}}
The following log is found after the first test is ran.
`TRUNCATE ... "auth_group_permissions", "auth_group", ...;; args=None`
A possible solution to this is to re-run data only migrations after
truncating the tables.
--
Ticket URL: <https://code.djangoproject.com/ticket/28400>
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