Poly diff to list changed bases/components for CI testing

[BeRT2me]

Is your feature request related to a problem? Please describe.
poetry poly diff -s is an amazing tool for a CI environment, but when working in a large project where tests for components/bases can become rather extensive, it would be nice to be able to get a simple list of those which were updated as well. (Rather than having to run all tests)

Describe the solution you'd like
Something like:
poetry poly diff bases --> base1 base3
poetry poly diff components --> component2 component4

Describe alternatives you've considered
Maybe -s flag, and/or bases/components as flags rather than an argument.

Nice to have would be a list of test paths, so you could just run :

poetry run pytest `poetry poly diff --test-paths`

Additional context

# Test projects by using their self-defined dependencies.
for val in `poetry poly diff -s`
do
    poetry install --sync -C ./projects/${val}
    poetry install --only=dev
    for base in `poetry poly diff bases -C ./projects/${val}`
    do
        poetry run pytest ./test/proj/bases/${base}
    done
done

cd test/proj/components && poetry run pytest `poetry poly diff components`

[DavidVujic]

Good ideas @BeRT2me!

I have thought about this, and ways of implementing a poly test command that should be able to run tests for the changed bricks only. Inspired by the Clojure tooling: https://polylith.gitbook.io/poly/commands#test

This will probably be doable when using the Polylith structure also for the tests,
such as test/<component-or-base>/<top-namespace>/<brick-name>.

If not disabled in the workspace.toml, a unit test template file is created when running poetry poly create for a component or base. Another idea I have is to add Pytest markers to the template (but then the tool will assume that the test tool is actually pytest). Alternatively, write about this as suggestions in the docs on how to run tests in an efficient way, by using markers.

The markers could be the corresponding brick name, and with some help from the diff command we have a list of changed bricks matching the markers when running pytest.

[DavidVujic]

Hello again @BeRT2me!

I have added a new option to the poly diff command, to make it easier running tests for changed code only. I hope this will be useful for you. It is available in v1.11.0 of the tool.

Here's updated docs about the option and how it can be used for testing with pytest:
https://davidvujic.github.io/python-polylith-docs/commands/#testing