Document tox in README

README.md

@@ -17,3 +17,52 @@ https://redis-tasks.readthedocs.io/en/latest/).
 ## Monitoring
 Want to monitor `redis-tasks` tasks, queues and workers? Check out [rt-dashboard](
 https://github.com/djangsters/rt-dashboard) - a monitoring tool for `redis-tasks`.
+
+## Contributing
+[tox](https://tox.readthedocs.io/en/latest/index.html) is used to run the tests 
+and automatically sets up virtual environments to run the tests in. It 
+implicitly uses [virtualenv]( https://virtualenv.pypa.io/en/latest/).
+To install `tox` run
+```
+pip install tox
+```
+Make sure to install the supported python versions on your local machine.
+If you don't want to install all supported python versions, you can either 
+explicitly specify environments you want to run `tox` in or alternatively you
+could run `tox` with the [--skip_missing_interpreters](
+https://tox.readthedocs.io/en/latest/config.html#conf-skip_missing_interpreters)
+flag.
+
+### Running tests
+You can run all the tests with
+```
+tox
+```
+or run specific test environments, for example only tests on Python 3.8, with
+```
+tox -e py38
+```
+If you want to customize the pytest run, you can pass in pytest arguments 
+after the `--` like so
+```
+tox -e py38 -- tests/test_cli.py
+```
+This will run tests only on Python 3.8 and from one module `tests/test_cli.py`
+only.
+
+### Running linter checks
+You can run `flake8` checks with 
+```
+tox -e flake8
+```
+`flake8` checks are also run as a part of the all tests run with
+```
+tox
+```
+
+### Building documentation locally
+You can build documentation locally with 
+```
+tox -e docs
+```
+The built html files will be located in `docs/build/html`.