BuildTestBase makes assumptions it should not about the code layout

This blocks 📌 Start using gitlab ci in addition to Drupalci for testing Needs work , which slows down the Automatic Updates initiative.

This is working in https://git.drupalcode.org/project/locale_deploy/-/tree/1.0.x/tests/src/... see 📌 Fix build test on gitlabci Fixed

Only one failure:

    1) Drupal\BuildTests\Framework\Tests\BuildTestTest::testCopyCodebaseExclude
    Failed asserting that file
    "/tmp/build_workspace_b44d87ed120fbe0c41c5d4572777553dQLQ8rc/copied_codebase/modules/my_module/vendor/my_vendor/composer.json"
    exists.

Which is extra special, because it's a test for the build test infrastructure, and it uses VFS. It's the only build test test using VFS.

I think the problem is that the build test infra in the MR is using Composer\InstalledVersions, but in the VFS mock, there's nothing composer-related?

I wonder if it would be simpler to not use VFS? 🤔

I've addressed @Wim Leers's review.

Looks perfect now! 🚀

Committed/pushed to 11.x (which will also be 10.3.x once it's branched), thanks!

I think we could probably backport this to 10.2.x since it's test only, but can't get my head around whether there's any bc implications for contrib/custom build tests at all - feels like there are not, but leaving PTBP for a bit.

Contrib build tests running on DrupalCI are completely broken atm. I wrote this MR to fix the 1 contrib module I know that has a build test. I think this is worth backporting. As you can see from the MR none of the core build tests have had to change due to this MR - it's only the tests of the build tests that have.

Fair enough. Cherry-picked to 10.2.x.

Automatically closed - issue fixed for 2 weeks with no activity.