# Testing

Quart’s usage of global variables (`request` etc) makes testing any code that uses these variables more difficult. To combat this it is best practice to only use these variables in the code directly called by Quart e.g. route functions or before request functions. Thereafter Quart provides a testing framework to control these globals.

Primarily testing should be done using a test client bound to the Quart app being tested. As this is so common there is a helper method `test_client()` which returns a bound client, e.g.

    async def test_app(app):
        client = app.test_client()
        response = await client.get('/')
        assert response.status_code == 200

## Event loops

To test with quart you will need to have an event loop in order to call the async functions. This is possible to do manually, for example

    def aiotest(func):
        loop = asyncio.get_event_loop()
        loop.run_until_complete(func())

    @aiotest
    async def test_app(app)
        ...

However it is much easier to use `pytest-asyncio` and the to do this for you. Note that `pytest` is the recommended test runner and the examples throughout assume `pytest` is used with `pytest-asyncio`.

## Calling routes

The test client has helper methods for all the HTTP verbs e.g. `post()`. These are helper methods for `open()`, as such all the methods at a minimum expect a path and optionally can have query parameters, json or form data. A standard `Response` class is returned. An example:

    async def test_create(app):
        test_client = app.test_client()
        data = {'name': 'foo'}
        response = await test_client.post('/resource/', json=data)
        assert response.status_code == 201
        result = await response.get_json()
        assert result == data

To test test routes which stream requests or responses, use the `request()` method:

    async def test_stream() -> None:
        test_client = app.test_client()
        async with test_client.request(...) as connection:
            await connection.send(b"data")
            await connection.send_complete()
            ...
            # receive a chunk of the response
            data = await connection.receive()
            ...
        # assemble the rest of the response without the first bit
        response = await connection.as_response()

To learn more about streaming requests and responses, read Consuming the request body and Streaming responses.

## Context testing

It is often necessary to test something within the app or request contexts. This is simple enough for the app context,

    async def test_app_context(app):
        async with app.app_context():
            current_app.[use]

for the request context however the request context has to be faked, at a minimum this means the method and path must be supplied, e.g.

    async def test_app_context(app):
        async with app.test_request_context("/", method="GET"):
            request.[use]

Note

Any `before_request` or `after_request` functions are not called when using the `test_request_context`. You can add `await app.preprocess_request()` to ensure the `before_request` functions are called.

    async def test_app_context(app):
        async with app.test_request_context("/", method="GET"):
            await app.preprocess_request()
            # The before_request functions have now been called
            request.[use]