Denis

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By Denis Nuțiu

2 minute read

Hi đź‘‹

In this article I will show you how to test your Python projects with Tox.

Introduction

Tox is a tool for automating testing in Python, their vision is to standardize the testing process. It can be used to easily test your project using multiple Python interpreters and run various commands.

Getting Started

To get started all you need to add to your project is a tox.ini file. To simplify running the tests we will make use of the following Dockerfile, which contains Python interpreters for 3.6 and 3.7

FROM ubuntu:20.04RUN apt update && apt install -y software-properties-common \               && add-apt-repository ppa:deadsnakes/ppa \               && apt install -y python3.6 && apt install -y python3.7 \               && apt install -y python3-pip && pip3 install toxVOLUME /codeWORKDIR /codeENTRYPOINT tox

A tox.ini file which tests using python 3.6 and python 3.7 looks like this:

# content of: tox.ini , put in same dir as setup.py[tox]skip_missing_interpreters = Trueenvlist = py36,py37[testenv]# install pytest in the virtualenv where commands will be executeddeps =    pytest==6.2.1    pytest-cov==2.11.1    responses==0.13.3commands =    # NOTE: you can run any command line tool here – not just tests    pytest[testenv:bamboo]commands =  pytest —junitxml=results.xml \    —cov=your-module—cov-config=tox.ini —cov-report=xml    coverage2clover -i coverage.xml -o clover.xmldeps =    {[testenv]deps}    coverage2clover

We have two environments: testenv and testenv:bamboo, the later one being used for coverage reporting in Bamboo using clover. To run Tox with a specific environment you’d type tox -e bamboo.

To run the test via the Dockerfile, first you’d build the docker container using: docker build . -f Dockerfile -t tox

Then, you’d run the container with docker run -v “$(pwd)”:”/code” tox -e bamboo to test with the Bamboo environment or just docker run -v “$(pwd)”:”/code” tox for the default env.

Practical Example

Here’s an example that you can use to follow along. We have the following files:

@denis âžś tox_article ls__pycache__  tests.py  tox.ini
# @denis âžś tox_article cat tests.pyimport unittestclass TestStringMethods(unittest.TestCase):    def test_upper(self):        self.assertEqual('foo'.upper(), 'FOO')    def test_isupper(self):        self.assertTrue('FOO'.isupper())        self.assertFalse('Foo'.isupper())    def test_split(self):        s = 'hello world'        self.assertEqual(s.split(), ['hello', 'world'])        # check that s.split fails when the separator is not a string        with self.assertRaises(TypeError):            s.split(2)if __name__ == '__main__':    unittest.main()%
# @denis âžś tox_article cat tox.ini[tox]skip_missing_interpreters = Trueenvlist = py36,py37skipsdist = True[testenv]commands =    python -m unittest%

Running Tox in our docker image will yield the following output:

@denis âžś tox_article docker run -v "$(pwd)":"/code" toxpy36 create: /code/.tox/py36py36 run-test-pre: PYTHONHASHSEED='520882151'py36 run-test: commands[0] | python -m unittest...----------------------------------------------------------------------Ran 3 tests in 0.000sOKpy37 create: /code/.tox/py37py37 run-test-pre: PYTHONHASHSEED='520882151'py37 run-test: commands[0] | python -m unittest...----------------------------------------------------------------------Ran 3 tests in 0.000sOK___________________________________ summary ____________________________________  py36: commands succeeded  py37: commands succeeded  congratulations :)

The same tests are run twice, first with Python 3.6 and then with Python 3.7.

Thanks for reading and happy testing! 🔧