#28400: TransactionTestCase will truncate data created from data migration
-------------------------------------+-------------------------------------
Reporter: Jared Mackey | Owner: nobody
Type: Bug | Status: new
Component: Testing framework | Version: 1.11
Severity: Normal | Resolution:
Keywords: tests,data- | Triage Stage:
migrations | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Jared Mackey:
Old description:
> 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.
New description:
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. I am
filling as a bug as I would expect that data created before tests are ran
would persist a transaction rollback during the test cases. A possible
solution to this is to re-run data only migrations after truncating the
tables.
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`
--
--
Ticket URL: <https://code.djangoproject.com/ticket/28400#comment:1>
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