Run pytest against a specific Python version using Docker

For datasette issue #1802 I needed to run my pytest test suite using a specific version of Python 3.7.

I decided to do this using Docker, using the official python:3.7-buster image.

Here's the recipe that worked for me:

docker run --rm -it -v `pwd`:/code \
  python:3.7-buster \
  bash -c "cd /code && pip install -e '.[test]' && pytest"

This command runs interactively so I can see the output (the -it option).

It mounts the current directory (with my testable application in it - I ran this in the root of a datasette checkout) as the /code volume inside the container.

The --rm option ensures that the container used for the test will be deleted once the test has completed (not just stopped).

It then runs the following using bash -c:

cd /code && pip install -e '.[test]' && pytest

This installs my project's dependencies and test dependencies and then runs pytest.

The truncated output looks like this:

% docker run -it -v `pwd`:/code \
  python:3.7-buster \
  bash -c "cd /code && pip install -e '.[test]' && pytest"
Obtaining file:///code
  Preparing metadata ( ... done
Collecting asgiref>=3.2.10
  Downloading asgiref-3.5.2-py3-none-any.whl (22 kB)
Installing collected packages: rfc3986, mypy-extensions, iniconfig, zipp, typing-extensions, typed-ast, tomli, soupsieve, sniffio, six, PyYAML, pyparsing, pycparser, py, platformdirs, pathspec, mergedeep, MarkupSafe, itsdangerous, idna, hupper, h11, execnet, cogapp, certifi, attrs, aiofiles, python-multipart, packaging, Jinja2, janus, importlib-metadata, cffi, beautifulsoup4, asgiref, anyio, pluggy, pint, httpcore, cryptography, click, asgi-csrf, uvicorn, trustme, pytest, httpx, click-default-group-wheel, black, pytest-timeout, pytest-forked, pytest-asyncio, datasette, blacken-docs, pytest-xdist
  Running develop for datasette
========================================================= test session starts ==========================================================
platform linux -- Python 3.7.13, pytest-7.1.3, pluggy-1.0.0
SQLite: 3.27.2
rootdir: /code, configfile: pytest.ini
plugins: asyncio-0.19.0, anyio-3.6.1, timeout-2.1.0, xdist-2.5.0, forked-1.4.0
asyncio: mode=strict
collected 1054 items                                                                                                                   

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Created 2022-09-05T16:23:06-07:00, updated 2022-09-06T10:51:25-07:00 · History · Edit