@Nightcrawler though I am not sure what
composer require will behave in that
project-files-installed light spot.
I didn't do a composer-create, I copied the files from my 'base project' but yes, they definitely exist on the host server along with the composer.json that will be executed.
autoloader might be missing them.
don't get to dev/build. Did a composer dump-autoload, generated new files with 465 classes but no change
I'm doing some extra work the SS4 upgrade guide. https://docs.silverstripe.org/en/4/upgrading/
I'm thinking of adding a section specifically on how to update your unit tests, but I'm wondering if it's different enough to warrant it. Did any one have issues with this area in the past?