conftest.py

import os

import dj_database_url
import django
import pytest
from django.apps import apps
from django.core import management
from django.core.management.color import no_style
from django.db import connection
from django.test import TestCase, TransactionTestCase


@pytest.fixture(autouse=True)
def _reset_sequences(request):
    """Reset all database sequences so PKs start from 1 in each test.

    PostgreSQL sequences are non-transactional and persist across
    TestCase's transaction rollbacks. This fixture ensures every test
    gets predictable PKs starting from 1 regardless of execution order.
    No-op on SQLite and skipped for tests that don't use the database.
    """
    if connection.vendor != 'postgresql':
        return
    # Only run for tests that actually have database access.
    if not (request.cls and issubclass(request.cls, (TestCase, TransactionTestCase))):
        if 'db' not in request.fixturenames and 'transactional_db' not in request.fixturenames:
            return

    table_names = set(connection.introspection.table_names())
    models = [m for m in apps.get_models() if m._meta.db_table in table_names]
    sql_list = connection.ops.sequence_reset_sql(no_style(), models)
    if sql_list:
        with connection.cursor() as cursor:
            for sql in sql_list:
                cursor.execute(sql)


def pytest_addoption(parser):
    parser.addoption('--staticfiles', action='store_true', default=False,
                     help='Run tests with static files collection, using manifest '
                          'staticfiles storage. Used for testing the distribution.')


def pytest_configure(config):
    from django.conf import settings

    if os.getenv('DATABASE_URL'):
        databases = {
            'default': dj_database_url.config(),
            'secondary': dj_database_url.config(),
        }
    else:
        databases = {
            'default': {
                'ENGINE': 'django.db.backends.sqlite3',
                'NAME': ':memory:'
            },
            'secondary': {
                'ENGINE': 'django.db.backends.sqlite3',
                'NAME': ':memory:'
            },
        }

    settings.configure(
        DEBUG_PROPAGATE_EXCEPTIONS=True,
        DEFAULT_AUTO_FIELD="django.db.models.AutoField",
        DATABASES=databases,
        SITE_ID=1,
        SECRET_KEY='not very secret in tests',
        USE_I18N=True,
        STATIC_URL='/static/',
        ROOT_URLCONF='tests.urls',
        TEMPLATES=[
            {
                'BACKEND': 'django.template.backends.django.DjangoTemplates',
                'APP_DIRS': True,
                'OPTIONS': {
                    "debug": True,  # We want template errors to raise
                }
            },
        ],
        MIDDLEWARE=(
            'django.middleware.common.CommonMiddleware',
            'django.contrib.sessions.middleware.SessionMiddleware',
            'django.contrib.auth.middleware.AuthenticationMiddleware',
            'django.contrib.messages.middleware.MessageMiddleware',
        ),
        INSTALLED_APPS=(
            'django.contrib.admin',
            'django.contrib.auth',
            'django.contrib.contenttypes',
            'django.contrib.sessions',
            'django.contrib.sites',
            'django.contrib.staticfiles',
            'rest_framework',
            'rest_framework.authtoken',
            'tests.authentication',
            'tests.generic_relations',
            'tests.importable',
            'tests',
        ),
        PASSWORD_HASHERS=(
            'django.contrib.auth.hashers.MD5PasswordHasher',
        ),
    )

    # Add django.contrib.postgres when using a PostgreSQL database
    if settings.DATABASES['default']['ENGINE'] == 'django.db.backends.postgresql':
        settings.INSTALLED_APPS += (
            'django.contrib.postgres',
        )

    # guardian is optional
    try:
        import guardian  # NOQA
    except ImportError:
        pass
    else:
        settings.ANONYMOUS_USER_ID = -1
        settings.AUTHENTICATION_BACKENDS = (
            'django.contrib.auth.backends.ModelBackend',
            'guardian.backends.ObjectPermissionBackend',
        )
        settings.INSTALLED_APPS += (
            'guardian',
        )

    # Manifest storage will raise an exception if static files are not present (ie, a packaging failure).
    if config.getoption('--staticfiles'):
        import rest_framework
        settings.STATIC_ROOT = os.path.join(os.path.dirname(rest_framework.__file__), 'static-root')
        backend = 'django.contrib.staticfiles.storage.ManifestStaticFilesStorage'
        settings.STORAGES['staticfiles']['BACKEND'] = backend

    django.setup()

    if config.getoption('--staticfiles'):
        management.call_command('collectstatic', verbosity=0, interactive=False)


def pytest_collection_modifyitems(config, items):
    from django.conf import settings

    if settings.DATABASES['default']['ENGINE'] != 'django.db.backends.postgresql':
        skip_postgres = pytest.mark.skip(reason='Requires PostgreSQL database backend')
        for item in items:
            if 'requires_postgres' in item.keywords:
                item.add_marker(skip_postgres)