GithubAction: added job to verify tests fail without src/ changes

[staabm]

Refs laminas/laminas-continuous-integration-action#117

Refs phpstan/phpstan#8228 (comment)

[ondrejmirtes]

Some suggestions:

• Run it only if both src/ and tests/ were changed
• Run it only if the usual tests passed
• Somehow you need to evaluate that one of the items from the matrix failed, and consider that a success build. Otherwise the build should fail. Possibly you'll need to save the tests result in a machine-readable format, upload the artifact, and do an "evaluate" step with some custom logic written in PHP. I do a similar thing already for the issue bot.

[staabm]

I think it works as expected regarding

• Run it only if the usual tests passed
• evaluate that one of the items from the matrix failed

missing atm is

• a check to run all these checks only if both src/ and tests/ were changed
• a prettty action summary

(and of course the temp changes need to be reverted, as soon as we get everything running as expected)

[staabm]

I think we are feature complete.

• summary with accumulated failing test cases https://github.com/phpstan/phpstan-src/actions/runs/3553045875#summary-9719268731

• a run which skipped checks because it only contains tests/ but not src/ changes https://github.com/phpstan/phpstan-src/actions/runs/3553104875/jobs/5968433529 on commit 8b688fc

• a run which verified tests because it contained src/ and tests/ changes https://github.com/phpstan/phpstan-src/actions/runs/3553108621 on commit 7d73752

the job dependency graph

if you are fine with the result, I will re-enable all lines I previously commented to speedup the feedback loop.

[staabm]

If we agreed on this one, I can cleanup all the test code and remove the temporary changes

[staabm]

squashed and rebased

[phpstan-bot]

This pull request has been marked as ready for review.

[staabm]

@ondrejmirtes is this PR useful? should I rebase it for 1.10.x?