Test & Code in Python 125: pytest 6

About this Episode

pytest 6 is out. Specifically, 6.0.1, as of July 31.

And there's lots to be excited about.
Anthony Sottile joins the show to discuss features, improvements, documentation updates and more.

Full release notes / changelog

Some of what we talk about:

How to update (at least, how I do it)
- Run your test suites with 5.4.3 or whatever the last version you were using
- Update to 6
- Run again. Same output? Probably good.
- If there are any warnings, maybe fix those.
- You can also run with pytest -W error to turn warnings into errors.
- Then find out all the cool stuff you can do now
New Features
- pytest now supports pyproject.toml files for configuration.
  - but remember, toml syntax is different than ini files. mostly quotes are needed
- pytest now includes inline type annotations and exposes them to user programs.
  - Most of the user-facing API is covered, as well as internal code.
- New command-line flags --no-header and --no-summary
- A warning is now shown when an unknown key is read from a config INI file.
  - The --strict-config flag has been added to treat these warnings as errors.
- New required_plugins configuration option allows the user to specify a list of plugins, including version information, that are required for pytest to run. An error is raised if any required plugins are not found when running pytest.
Improvements
- You can now pass output to things like less and head that close the pipe passed to them.
  - thank you!!!
- Improved precision of test durations measurement.
  - use --durations=10 -vv to capture and show durations
- Rich comparison for dataclasses and attrs-classes is now recursive.
- pytest --version now displays just the pytest version,
  - while pytest --version --version displays more verbose information including plugins.
- --junitxml now includes the exception cause in the message XML attribute for failures during setup and teardown.
Improved Documentation
- Add a note about --strict and --strict-markers and the preference for the latter one.
- Explain indirect parametrization and markers for fixtures.
Bug Fixes
Deprecations
Trivial/Internal Changes
Breaking Changes you might need to care about before upgrading
- PytestDeprecationWarning are now errors by default.
  - Check the deprecations and removals page if you are curious.
- -k and -m internals were rewritten to stop using eval(), this results in a few slight changes but overall makes them much more consistent
- testdir.run().parseoutcomes() now always returns the parsed nouns in plural form.
  - I'd say that's an improvement