Thanks for the review @Seldaek! I've updated the config key name and json schema. Unfortunately, I had to remove the test as it was not working - I realized it doesn't actually test the command but rather the underlying installer so the config was not applied there. I think a bigger change would be needed to test such scenario.

We could add an InstallerFactory which would create an instance of Installer from InputInterface and Config, resolving the parameters accordingly. Moving Installer instantiation would improve testability and reduce repetitions pointed out above and improve readability.

Yep to support this in tests you'd need to update https://github.com/composer/composer/blob/main/tests/Composer/Test/InstallerTest.php#L420 too.

InstallerTest creates their own simplified version of update command and mocks Config too. We could add support to read config from .test file and apply it to the mock but that still won't verify actual command behaviour.

Let me try to pick it up as an improvement in a separate PR, if that's ok 🙏🏻

yeah please don't mix this in this PR for sure :D Not sure if much can be done about this.. I don't really mind it's not using the real command, because these .test files are about testing the Installer class and the solver internals in integration, the command class is irrelevant here.

Thanks