How to override a pytest fixture calling the original in pytest 4

Question

I am defining a pytest fixture that to overrides the django_db_setup fixture.

The change I have sets up additional teardown for safety, as there are integration tests th

Answer 1

There is a simple trick to redefine a fixture with a custom impl. Just declare a fixture with the same name and signature in your local test code (I usually do it in the conftest.py in project root). Examples:

"Inheritance"

# conftest.py

import pytest


@pytest.fixture(scope='session')
def django_db_setup(
    request,
    django_db_setup,
    django_test_environment,
    django_db_blocker,
    django_db_use_migrations,
    django_db_keepdb,
    django_db_createdb,
    django_db_modify_db_settings,
):
    # do custom stuff here
    print('my custom django_db_setup executing')

Notice I have django_db_setup argument in the custom django_db_setup fixture - this ensures the original fixture is called before the custom one.

"Redeclaration"

If you omit the argument, the custom fixture will replace the original one, so it won't be executed:

@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,
):
    print((
        'my custom django_db_setup executing - '
        'original django_db_setup will not run at all'
    ))

BTW, this is another handy trick to use when you e.g. want to turn off a fixture that is defined elsewhere.