Pytest use django_db with rest framework

Question

I am trying to get a simple test to work against the real django_db not the test database using the django rest framework.

Basic test setup:

import pytest
from django.urls import reverse
from rest_framework import status
from rest_framework.test import APIClient

@pytest.mark.django_db
def test_airport_list_real():
    client = APIClient()
    response = client.get(reverse('query_flight:airports-list'))
    assert response.status_code == 200
    assert len(response.json()) > 0

Running this test I get:

___________________________ test_airport_list_real ____________________________

    @pytest.mark.django_db
    def test_airport_list_real():
        client = APIClient()
        response = client.get(reverse('query_flight:airports-list'))
        assert response.status_code == 200
>       assert len(response.json()) > 0
E       assert 0 > 0
E        +  where 0 = len([])
E        +    where [] = functools.partial(<bound method Client._parse_json of <rest_framework.test.APIClient object at 0x000001A0AB793908>>, <Response status_code=200, "application/json">)()
E        +      where functools.partial(<bound method Client._parse_json of <rest_framework.test.APIClient object at 0x000001A0AB793908>>, <Response status_code=200, "application/json">) = <Response status_code=200, "application/json">.json

query_flight\tests\query_flight\test_api.py:60: AssertionError

When just running in the shell using pipenv run python manage.py shell I get the expected results: In [1]: from django.urls import reverse

In [2]: from rest_framework.test import APIClient

In [3]: client = APIClient()

In [4]: response = client.get(reverse('query_flight:airports-list'))

In [5]: len(response.json())
Out[5]: 100

Using the following packages:

pytest-django==3.2.1
pytest [required: >=2.9, installed: 3.5.1]
djangorestframework==3.8.2
django [required: >=1.8, installed: 2.0.5]

Is there anyway to get pytest to access the real database in this way?

Answer 1

The django_db marker is only responsible to provide a connection to the test database for the marked test. The django settings passed to pytest-django are solely responsible for the selection of database used in the test run.

You can override the database usage in pytest-django by defining the django_db_setup fixture. Create a conftest.py file in the project root if you don't have it yet and override the db configuration:

# conftest.py
import pytest

@pytest.fixture(scope='session')
def django_db_setup():
    settings.DATABASES['default'] = {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': 'path/to/dbfile.sqlite3',
    }

However, you shouldn't use the real database in tests. Make a dump of your current db to get a snapshot of test data (python manage.py dumpdata > testdata.json) and load it into an empty test database to populate it before the test run:

# conftest.py
import pytest
from django.core.management import call_command

@pytest.fixture(scope='session')
def django_db_setup(django_db_setup, django_db_blocker):
    with django_db_blocker.unblock():
        call_command('loaddata', 'testdata.json')

Now, you can't possibly corrupt your real db when running tests; any future changes in real db will not cause the tests to fail (for example, when some data was deleted) and you always have a deterministic state on each test run. If you need some additional test data, add it in JSON format to testdata.json and your tests are good to go.

Source: Examples in pytest-django docs.