pytest-tornasync

A simple pytest plugin that provides some helpful fixtures for testing Tornado (version 5.0 or newer) apps and easy handling of plain (undecoratored) native coroutine tests (Python 3.5+).

Why another Tornado pytest plugin when the excellent pytest-tornado already exists? The main reason is that I didn't want to have to decorate every test coroutine with @pytest.mark.gen_test. This plugin doesn't have anything like gen_test. Defining a test with async def and a name that begins with test_ is all that is required.

Installation

Install using pip, which must be run with Python 3.5+:

pip install pytest-tornasync

Usage

Define an app fixture:

import pytest


@pytest.fixture
def app():
    import yourapp
    return yourapp.make_app()  # a tornado.web.Application

Create tests as native coroutines using Python 3.5+ async def:

async def test_app(http_server_client):
    resp = await http_server_client.fetch('/')
    assert resp.code == 200
    # ...

Fixtures

When the plugin is installed, then pytest --fixtures will show the fixtures that are available:

http_server_port

Port used by http_server.

http_server

Start a tornado HTTP server that listens on all available interfaces.

You must create an app fixture, which returns the tornado.web.Application to be tested.

Raises: FixtureLookupError: tornado application fixture not found

http_server_client

Create an asynchronous HTTP client that can fetch from http_server.

http_client

Create an asynchronous HTTP client that can fetch from anywhere.

io_loop

Create a new tornado.ioloop.IOLoop for each test case.

Examples

import time

import tornado.web
import tornado.gen

import pytest


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world!")


@pytest.fixture
def app():
    return tornado.web.Application([(r"/", MainHandler)])


async def test_http_server_client(http_server_client):
    # http_server_client fetches from the `app` fixture and takes path
    resp = await http_server_client.fetch('/')
    assert resp.code == 200
    assert resp.body == b"Hello, world!"


async def test_http_client(http_client):
    # http_client fetches from anywhere and takes full URL
    resp = await http_client.fetch('http://httpbin.org/status/204')
    assert resp.code == 204


async def example_coroutine(period):
    await tornado.gen.sleep(period)


async def test_example():
    # no fixtures needed
    period = 1.0
    start = time.time()
    await example_coroutine(period)
    elapsed = time.time() - start
    assert elapsed >= period