Automatic Test Runner Engine

tdd, unit-testing, test, runner, django, live-coding, pycharm, pycrunch-engine
pip install pycrunch-engine==1.4


Quick start

pip install pycrunch-engine

This engine depends on aiohttp, you may need to check cross-dependencies if your project also uses aiohttp

PyCrunch is written and supports Python 3.6+.

What Covers What

How to run:

Using PyCharm Connector extension

Download extension and install it from disk using PyCharm

Open your project in PyCharm, and select "Run/Restart PyCrunch Engine"

Engine will be started automatically, and you will be able to see your test in PyCrunch plugin window

Manual (Without PyCharm)

In python project root, run:


Optionally, port can be specified, in order to run more than one instance of engine:

pycrunch-engine --port=31234

Configuration file

Configuration file should be created prior to the first use of pycrunch-engine

Configuration file .pycrunch-config.yaml should be created and placed at project root

Minimum configuration

  runtime: pytest

Django configuration

  - front/
  - build/
  runtime: django
  DJANGO_SETTINGS_MODULE: djangoapp.settings.local

Configuration File may be checked-in the to source control, to allow other developers to use engine.

Beta restriction

For Django, you probably need to disable logging, pasting following line in your settings file:


This issue is already on roadmap and will be addressed soon.

Django Support Details

Primary goal of extension is to run as fast as possible.

Default Django Test Runner creates new database each time when tests are run.

This leads to multiple problems:

  • Inability to run tests in parallel
  • Sometimes database got stale, and you need to type yes in terminal in order to destroy it
  • Each test run consumes more resources than it should, by creating database and applying migrations each time
  • Tests are not really unit-tests, sometimes you do not need database at all
  • Cannot run tests (or some code from unit-test) upon data stored in local database

As a result, pycrunch will use same database for running tests as runserver, without initializing temporary database.

Be careful when you run your suite for the first time, as it may corrupt data.

If your insist on using separate database, please create new django.setting module and pass it as environment variable to pycrunch-engine using .pycrunch-config.yaml file in env section, something like

 runtime: django
 DJANGO_SETTINGS_MODULE: djangoapp.settings.pycrunch_local

Running in Docker

Some developers are using docker or docker-compose to set up environment and run development server in docker container

pycrunch-engine and extension support this use case.

All you need, is to map some port from docker to your local machine (ex. 5000) and put additional path-mapping configuration inside .pycrunch-config.yaml:

  runtime: django
  DJANGO_SETTINGS_MODULE: djangoapp.settings.pycrunch_local
    /code: /Users/neo/code/matrix-django-api

You will probably need to rebuild containers using docker-compose up --build in order for exposed port to appear

Then, enter inside docker container (ex:)

docker-compose exec web bash
# inside container:
# will run on 5000 port by default

From PyCharm extension menu, select "Connect to Custom PyCrunch Engine"