Currently for pytest we just outright exclude scm_unittest, as we do with test-webkitpy. However, there's no need to ignore absolutely everything; there are some tests in there which aren't slow, so instead we should explicitly mark those which are slow. (Aside: I thought I'd already filed this and posted patch, but seemingly not?)
Created attachment 427280 [details] Patch
<rdar://problem/77566017>
Committed r277089 (237392@main): <https://commits.webkit.org/237392@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 427280 [details].