Summary:
Yoga has a known bug where marginStart and marginEnd will swap with row-reverse flex direction. This is not the intended behavior. On Paper this is also an issue with marginLeft and marginRight (at least we think Paper is the culprit, not exactly clear yet).
margin-start (and end) is not actually valid css. The gentest.rb script will just turn this into margin-left, but the cpp generated will properly test marginStart. This seems a bit weird to be since marginStart != marginLeft AFAIK. Things like RTL and LTR modes might make this test not exactly right. But given how many other tests depend on this quirk I think it is fine to add as is - the end result is the same after all. If not, a followup would be to add support for mapping margin-inline-start (valid css) to marginStart.
Anyway, this diff is to add test coverage for this scenario. Next stop is to actually try to fix this problem, which may be a bit harder :P
See https://github.com/facebook/yoga/issues/1208 for more info.
Reviewed By: NickGerleman
Differential Revision: D49744271
fbshipit-source-id: 75b8dd0cc5c53b2f338476fb70b60006aaa89054
e60ae290ea