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Description:

pytestasyncsqlalchemy 0.2.0

pytest-async-sqlalchemy

Database testing fixtures using the SQLAlchemy asyncio API
You can install "pytest-async-sqlalchemy" via pip from PyPI
$ pip install pytest-async-sqlalchemy

Setup
Providing a Session Scoped Event Loop
The first thing to do is to declare an even_loop fixture with the scope set as "session".
You can copy & paste the code below to your conftest.py:
@pytest.fixture(scope="session")
def event_loop():
"""
Creates an instance of the default event loop for the test session.
"""
if sys.platform.startswith("win") and sys.version_info[:2] >= (3, 8):
# Avoid "RuntimeError: Event loop is closed" on Windows when tearing down tests
# https://github.com/encode/httpx/issues/914
asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

loop = asyncio.new_event_loop()
yield loop
loop.close()

This is required since pytest-async-sqlalchemy shares the database connection between tests
for performance reasons, but the default even_loop fixture defined by
pytest-asyncio is function scoped1 (i.e., it
kills the database connection after each test).
Providing Database URL and Initialization
pytest-async-sqlalchemy provides placeholders to configure and initialize
the testing database: database_url and init_database. These two must be
defined in your project conftest.py like below:
@pytest.fixture(scope="session")
def _database_url():
return "postgresql+asyncpg://postgres:masterkey@localhost/dbtest"

@pytest.fixture(scope="session")
def init_database():
from myprorject.db import metadata

return metadata.create_all

The _database_url must be a session-scoped fixture that returns the database URL in
SQLAlchemy standard. init_database must also be a session-scoped fixture that returns
the callable used to initialize the database (in most cases, this would return the
metadata.create_all function).
Usage
This plugin provides the following fixtures:

db_session: An AsyncSession object bounded to the test session database. Database
transactions are discarded after each test function, so the same database is used for
the entire test suite (avoiding the overhead of initializing a database on every test).
database: An URL to the initialized test session database.
scoped_database: scoped_database provides a new database within the scope of the
test function. The value of the fixture is a string URL pointing to the database.

Contributing
Contributions are very welcome. Tests can be run with tox, please ensure
the coverage at least stays the same before you submit a pull request.
License
Distributed under the terms of the MIT license, "pytest-async-sqlalchemy" is free and open source software

1. pytest-async-sqlalchemy can't provide its own even_loop since pytest plugins are not
able to override fixtures from one another. So the only solution we have now is to aks the user to
declare its own event_loop fixture. Suggestions on how to overcome that in a better way are
welcome, hit us on the Issues section.