django 1.8 tests with models and migrations

Question

I use django 1.8 I have a model with reference to django.contrib.contenttypes.ContentType:

from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType


class TaggedItem(models.Model):
    tag = models.SlugField()
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')

    def __str__(self):              # __unicode__ on Python 2
        return self.tag

And I have a tests.py:

class TestObj(models.Model):
    value = models.IntegerField(default=42, null=False)

    def __str__(self):
        text = "%s-%i" % ("name", self.value)
        return text


class MyUnitTest(TestCase):
    def setUp(self):
        TestObj.objects.create(value=40)
        TestObj.objects.create()

    def test_my_test(self):
        obj1 = TestObj.objects.get(value=40)
        obj2 = TestObj.objects.get(value=42)
        self.assertEqual(obj1.value, 40)
        self.assertEqual(obj2.value, 42)

When I try to create DB without migrations (and "test" too), I get an error with an invalid reference:

./manage.py syncdb
...
django.db.utils.ProgrammingError: ERROR: reference "django_content_type" does not exist

But if I create a migration (./manage.py makemigrations myobj), migration contains only a models.py model (TaggedItem):

Migrations for 'myobj':
  0001_initial.py:
    - Create model TaggedItem

After I try to test my app and I get an error with reference myob_testobj does not exist:

./manage.py test -v3
Creating test database for alias 'default' ('testdb_49308_4288843')...
Operations to perform:
  Synchronize unmigrated apps: staticfiles
  Apply all migrations: myobj, contenttypes, sessions
Synchronizing apps without migrations:
Running pre-migrate handlers for application contenttypes
Running pre-migrate handlers for application sessions
Running pre-migrate handlers for application myobj
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Loading 'initial_data' fixtures...
Checking 'mypro' for fixtures...
No fixture 'initial_data' in 'mypro'.
Installed 0 object(s) from 0 fixture(s)
Running migrations:
  Rendering model states... DONE (0.010s)
  Applying contenttypes.0001_initial... OK (0.133s)
  Applying contenttypes.0002_remove_content_type_name... OK (0.017s)
  Applying myobj.0001_initial... OK (0.217s)
  Applying sessions.0001_initial... OK (0.233s)
Running post-migrate handlers for application contenttypes
Adding content type 'contenttypes | contenttype'
Running post-migrate handlers for application sessions
Adding content type 'sessions | session'
Running post-migrate handlers for application myobj
Adding content type 'myobj | taggeditem'
Adding content type 'myobj | testobj'
Traceback
...
django.db.utils.ProgrammingError: ERROR: reference "myobj_testobj" does not exist

If I don't use a migration and run test, table myobj_testobj was created but I get an error with no reference to "django_content_type"

/manage.py test -v3
Creating test database for alias 'default' ('testdb_773982_6463361')...
Operations to perform:
  Synchronize unmigrated apps: staticfiles, myobj
  Apply all migrations: contenttypes, sessions
Synchronizing apps without migrations:
Running pre-migrate handlers for application contenttypes
Running pre-migrate handlers for application sessions
Running pre-migrate handlers for application myobj
  Creating tables...
    Creating table myobj_taggeditem
    **Creating table myobj_testobj**
    Running deferred SQL...
Traceback
...
django.db.utils.ProgrammingError: ERROR: reference "django_content_type" does not exist

How do I use tests with models? Thank you.

Answer 1

Django cant discover model TestObj because your test.py is not an app and there is no any installed app that describes TestObj in settings.INSTALLED_APPS. You need to add model TestObj to module myobj.models.

After that run python manage.py makemigrations myobj and then migration for TestObj will be created. So you can run your tests.