pytest-flask

1.3.0 · active · verified Sat Apr 11

pytest-flask is an extension for the pytest test runner, providing a set of useful fixtures and tools to simplify the testing and development of Flask applications and extensions. It is currently at version 1.3.0 and actively maintained, with releases typically tied to Flask and pytest major version updates and bug fixes.

Warnings

breaking The `request_ctx` fixture was removed in version 1.3.0 due to compatibility changes with Flask 3.0.0. Older versions of pytest-flask using this fixture will be incompatible with Flask 3.0.0+.
Fix: Update to pytest-flask 1.3.0+ and refactor tests to not use `request_ctx`. Consider `app.test_request_context()` for manual context manipulation if necessary.
breaking The `live_server.url` method was removed in version 1.2.0. Direct access to the live server URL should use string formatting or `flask.url_for` with `_external=True`.
Fix: Remove `.url` calls. Construct URLs manually or use `flask.url_for(..., _external=True)` if testing a live server.
breaking Starting from version 1.0.0, the `live_server` fixture became session-scoped by default. This changes its lifecycle from function-scoped, potentially impacting tests expecting a fresh server for each test function.
Fix: If a function-scoped live server is required, configure `live-server_scope = function` in your `pytest.ini` file.
breaking Support for Python 2.7 and 3.4 was dropped in version 1.0.0. Ensure your testing environment uses Python 3.5 or newer.
Fix: Upgrade your Python environment to 3.5 or a later supported version (currently Python >=3.7 is required).
gotcha Older versions of `pytest-flask` might encounter incompatibilities with newer versions of Werkzeug (e.g., Werkzeug >=3.1). Check release notes and open issues for specific version requirements.
Fix: Always keep `pytest-flask` updated to the latest version to ensure compatibility with recent Flask and Werkzeug releases. If encountering issues, check `pytest-flask`'s GitHub issues for known incompatibilities.

Install

pip install pytest-flask Install stable version

Imports

app (fixture)
```
import pytest
# @pytest.fixture def app(): ...
```
pytest-flask fixtures like 'app', 'client', 'live_server' are auto-discovered by pytest and typically not imported directly from pytest_flask. You define your 'app' fixture, and then 'client' and 'live_server' use it.
client (fixture)
```
def test_something(client): ...
```
Accessed as an argument in your test functions after defining the 'app' fixture.
live_server (fixture)
```
def test_live_server_access(live_server): ...
```
Accessed as an argument in your test functions after defining the 'app' fixture.

Quickstart

To get started, define your Flask application factory in a module (e.g., `myapp.py`), then create a `pytest` fixture named `app` in your `conftest.py` file. This fixture will create and configure your Flask application for testing. The `client` fixture, provided by `pytest-flask`, will then be available in your tests to make requests against your application. Run tests with `pytest`.

# myapp.py
from flask import Flask

def create_app():
    app = Flask(__name__)

    @app.route('/hello')
    def hello():
        return 'Hello, World!'

    return app

# conftest.py
import pytest
from myapp import create_app

@pytest.fixture
def app():
    app = create_app()
    app.config.update({"TESTING": True}) # Recommended for testing
    yield app

@pytest.fixture
def client(app):
    return app.test_client()

# test_app.py
def test_hello_world(client):
    response = client.get('/hello')
    assert response.status_code == 200
    assert b'Hello, World!' in response.data

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