CSS-Values-3 reftests use a few helper-files that live in subdirectories called "iframe" and "reference", shown here: https://github.com/w3c/csswg-test/tree/master/css-values-3 We don't currently import those subdirectories, though -- we only import "support": https://dxr.mozilla.org/mozilla-central/source/layout/reftests/w3c-css/received/css-values-3 Perhaps we should import those other subdirectories? (Or: perhaps the tests need to be rewritten such that all of their resources live in "support/"? At first I thought there was a requirement to that effect, but I can't find any such requirement on http://testthewebforward.org/docs/reftests.html at the moment.)

We do have some imported tests that reference files in these subdirectories -- e.g. this one: https://dxr.mozilla.org/mozilla-central/rev/054d4856cea6150a6638e5daf7913713281af97d/layout/reftests/w3c-css/received/css-values-3/vh-support-transform-origin.html#39 > <iframe src="iframe/vh-support-transform-origin.html"></iframe> ...though this test is marked "skip" at the moment: https://dxr.mozilla.org/mozilla-central/rev/054d4856cea6150a6638e5daf7913713281af97d/layout/reftests/w3c-css/received/reftest.list#97 ...perhaps because it fails due to this missing helper-file (not sure).

(In reply to Daniel Holbert [:dholbert] from comment #1) > ...perhaps because it fails due to this missing helper-file (not sure). That's right. It's bug 1256580. See https://dxr.mozilla.org/mozilla-central/rev/054d4856cea6150a6638e5daf7913713281af97d/layout/reftests/w3c-css/failures.list#29-31

Oh, I guess actually this is a duplicate of that bug.

Ah, looks like it. Thanks!