It seems that
resolve removes packages under [extra] (in Project.toml) from the Manifest.toml.
Is this intended behavior? It implies that
instante'ing a package is not enough to make it testable, and that packages that are only required for testing might get completely removed from the system after a call to
gc (if no other project references it).
extra are not put in the Manifest at all (except when they are used) and they will indeed be garbage collected.
I am kinda coming around thinking that the whole
target thing was perhaps a mistake, or at least not thought through enough for it to make sense for it to been implemented, and something like PSA: Use a project for building your docs (but for testing) should be used instead.
Using that means the testing environment is fully reproducible, which is not the case right now.