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I am trying to implement a many-to-many scenario using peewee python ORM and I'd like some unit tests. Peewee tutorial is great but it assumes that database is defined at module level then all models are using it. My situation is different: I don't have a source code file (a module from python's point of view) with tests which I run explicitly, I am using nose which collects tests from that file and runs them.

How do I use a custom database only for models instantiated in tests (which are being run by nose)? My goal is to use an in-memory database for tests only, to speedup the testing process.

Answers

I just pushed a commit today that makes this easier.

The fix is in the form of a context manager which allows you to override the database of a model:

from unittest import TestCase
from playhouse.test_utils import test_database
from peewee import *

from my_app.models import User, Tweet

test_db = SqliteDatabase(':memory:')

class TestUsersTweets(TestCase):
    def create_test_data(self):
        # ... create a bunch of users and tweets
        for i in range(10):
            User.create(username='user-%d' % i)

    def test_timeline(self):
        with test_database(test_db, (User, Tweet)):
            # This data will be created in `test_db`
            self.create_test_data()

            # Perform assertions on test data inside ctx manager.
            self.assertEqual(Tweet.timeline('user-0') [...])

        # once we exit the context manager, we're back to using the normal database

See the documentation and have a look at the example testcases:

• Context manager
• Testcases showing how to use