The initial implementation of test-verify-wpt simply assesses, for each changed file, is that file a test path in the web-platform test manifest? There is existing wpt code that does a better job of this and could probably be re-used with minor adjustments. As pointed out by jgraham in https://bugzilla.mozilla.org/show_bug.cgi?id=1411660#c7: """ So, wpt also has a function to get a list of affected tests (and types) from a list of changed files, see [1]. We don't need to switch to that as a prerequisite to landing this, but it does try to do a little better than just checking which changed files are tests because it tries to figure out if the file is a support file that's used by some other test that will be run. Switching to that will make this work just like upstream in terms of the tests that are run, which is what we ideally want. [1] https://searchfox.org/mozilla-central/source/testing/web-platform/tests/tools/wpt/testfiles.py#261-286 """