[Django]-How to create table during Django tests with managed = False

You can use SchemaEditor in TestCase.setUp method to explicitly create models with managed = False.

# models.py

from django.db import models


class Unmanaged(models.Model):
    foo = models.TextField()

    class Meta:
        # This model is not managed by Django
        managed = False
        db_table = 'unmanaged_table'

And in your tests:

# tests.py

from django.db import connection
from django.test import TestCase

from myapp.models import Unmanaged


class ModelsTestCase(TestCase):
    def setUp(self):
        super().setUp()

        with connection.schema_editor() as schema_editor:
            schema_editor.create_model(Unmanaged)

            if (
                Unmanaged._meta.db_table
                not in connection.introspection.table_names()
            ):
                raise ValueError(
                    "Table `{table_name}` is missing in test database.".format(
                        table_name=Unmanaged._meta.db_table
                    )
                )

    def tearDown(self):
        super().tearDown()

        with connection.schema_editor() as schema_editor:
            schema_editor.delete_model(Unmanaged)

    def test_unmanaged_model(self):
        with self.assertNumQueries(num=3):
            self.assertEqual(0, Unmanaged.objects.all().count())
            Unmanaged.objects.create()
            self.assertEqual(1, Unmanaged.objects.all().count())

Execute raw SQL to create the table in the test setup:

from django.db import connection

class MyTest(unittest.TestCase):
    def setUp(self):
        connection.cursor().execute("CREATE TABLE ...")

    def tearDown(self):
        connection.cursor().execute("DROP TABLE ...")

Nice plug and play solution. Just paste this before your test class definition. (note: django 1.8 used)

from django.db.models.loading import get_models

def change_managed_settings_just_for_tests():
  """django model managed bit needs to be switched for tests."""    

  unmanaged_models = [m for m in get_models() if not m._meta.managed]
  for m in unmanaged_models:
    m._meta.managed = True

change_managed_settings_just_for_tests()

A quick fix if you don’t have many unmanaged tables:

First add a new variable to the settings.

# settings.py
import sys
UNDER_TEST = (len(sys.argv) > 1 and sys.argv[1] == 'test')

then in the models

# models.py
from django.conf import settings

class SampleModel(models.Model):
    apple = models.CharField(max_length=30)
    orange = models.CharField(max_length=30)

    class Meta:
        managed = getattr(settings, 'UNDER_TEST', False)

Create your own test runner using this:

from django.test.simple import DjangoTestSuiteRunner

class NoDbTestRunner(DjangoTestSuiteRunner):
  """ A test runner to test without database creation """

  def setup_databases(self, **kwargs):
    """ Override the database creation defined in parent class """
    #set manage=True for that specific database on here

Then on your settings add this class to TEST_RUNNER.

Just to add :django.db.models.loading.get_models will be removed in Django 1.9 (see https://github.com/BertrandBordage/django-cachalot/issues/33).

Below is an updated one for Django 1.10:

class UnManagedModelTestRunner(DiscoverRunner):
    '''
    Test runner that automatically makes all unmanaged models in your Django
    project managed for the duration of the test run.
    Many thanks to the Caktus Group 
    '''

    def setup_test_environment(self, *args, **kwargs):
        from django.apps  import apps
        self.unmanaged_models = [m for m in apps.get_models() if not m._meta.managed]
        for m in self.unmanaged_models:
            m._meta.managed = True
        super(UnManagedModelTestRunner, self).setup_test_environment(*args, **kwargs)

    def teardown_test_environment(self, *args, **kwargs):
        super(UnManagedModelTestRunner, self).teardown_test_environment(*args, **kwargs)
        # reset unmanaged models
        for m in self.unmanaged_models:
            m._meta.managed = False 

Note you also need to take care migrations(see Testing django application with several legacy databases)

MIGRATION_MODULES = {
    'news': 'news.test_migrations',
    'economist': 'economist.test_migrations'
}

Using pytest and pytest-django

To make this work (has been tested with django 3.0.2, pytest 5.3.5 and pytest-django 3.8.0):

1. Run your pytest with the additional argument --no-migrations.
2. Put the following code in your conftest.py. This has an unfortunate amount of copypasta, but I could not figure out how to first make my models unmanaged and then call the original django_db_setup. The issue of not being able to call pytest fixtures directly is discussed here: https://github.com/pytest-dev/pytest/issues/3950

conftest.py

# example file
import pytest
from pytest_django.fixtures import _disable_native_migrations


@pytest.fixture(scope="session")
def django_db_setup(
        request,
        django_test_environment,
        django_db_blocker,
        django_db_use_migrations,
        django_db_keepdb,
        django_db_createdb,
        django_db_modify_db_settings,
):
    # make unmanaged models managed
    from django.apps import apps
    unmanaged_models = []
    for app in apps.get_app_configs():
        unmanaged_models = [m for m in app.get_models()
                            if not m._meta.managed]
    for m in unmanaged_models:
        m._meta.managed = True

    # copypasta fixture code

    """Top level fixture to ensure test databases are available"""
    from pytest_django.compat import setup_databases, teardown_databases

    setup_databases_args = {}

    if not django_db_use_migrations:
        _disable_native_migrations()

    if django_db_keepdb and not django_db_createdb:
        setup_databases_args["keepdb"] = True

    with django_db_blocker.unblock():
        db_cfg = setup_databases(
            verbosity=request.config.option.verbose,
            interactive=False,
            **setup_databases_args
        )

    def teardown_database():
        with django_db_blocker.unblock():
            try:
                teardown_databases(db_cfg, verbosity=request.config.option.verbose)
            except Exception as exc:
                request.node.warn(
                    pytest.PytestWarning(
                        "Error when trying to teardown test databases: %r" % exc
                    )
                )

    if not django_db_keepdb:
        request.addfinalizer(teardown_database)

After spending a few hours testing and researching ways to test my django unmanaged models, I finally came up with a solution that worked for me.
My implementation is in this below snippet. It’s working great with local tests using db.sqlite3.

# Example classes Implementation

from django.db import models, connection
from django.db.models.base import ModelBase as DjangoModelBase
from django.db.utils import OperationalError
from django.test import TransactionTestCase


class AbstractModel(models.Model):
    name = models.TextField(db_column="FIELD_NAME", blank=True, null=True)

    class Meta:
        managed = False
        abstract = True


class TestModel(AbstractModel):
    test_field = models.TextField(db_column="TEST_FIELD", blank=True, null=True)

    def test_method(self):
        print("just testing")

    class Meta(AbstractModel.Meta):
        db_table = "MY_UNMANAGED_TABLE_NAME"



# My Custom Django TestCases Implementation for my tests

def create_database(model):
    with connection.schema_editor() as schema_editor:
        try:
            schema_editor.create_model(model)
        except OperationalError:
            pass


def drop_database(model):
    with connection.schema_editor() as schema_editor:
        try:
            schema_editor.delete_model(model)
        except OperationalError:
            pass


class BaseModelTestCase(TransactionTestCase):
    """Custom TestCase for testing models not managed by django."""

    Model = DjangoModelBase

    def setUp(self):
        super().setUp()
        create_database(self.Model)

    def tearDown(self):
        super().tearDown()
        drop_database(self.Model)


class AbstractBaseModelTestCase(TransactionTestCase):
    """Custom TestCase for testing abstract django models."""

    Model = DjangoModelBase

    def setUp(self):
        # this is necessary for testing an abstract class
        self.Model = DjangoModelBase(
            "__TestModel__" + self.Model.__name__,
            (self.Model,),
            {"__module__": self.Model.__module__},
        )
        create_database(self.Model)

    def tearDown(self):
        drop_database(self.Model)



# Example of usage

class TestModelTestCase(BaseModelTestCase):
    Model = TestModel

    def setUp(self):
        super().setUp()
        self.instance = TestModel.objects.create()
        self.assertIsInstance(self.instance, TestModel)


class AbstractModelTestCase(AbstractBaseModelTestCase):
    Model = AbstractModel

    def setUp(self):
        super().setUp()
        self.instance = AbstractModel.objects.create()
        self.assertIsInstance(self.instance, AbstractModel)

p.s. I am not using any Django migrations as soon as my models are managed=False. So this was not necessary for me.

Simply move your unmanaged models to a dedicated app and delete migrations folder. Details in my answer in Multi db and unmanged models – Test case are failing