Visual tests are typically used when testing rendering of things that cannot be tested with reftests.
Their main advantage of over manual tests is they can be verified using browser-specific and platform-specific screenshots; note, however, that many browser vendors treat them identically to manual tests hence they are similarly discouraged as they very infrequently, if ever, get run by them.
Writing a Visual Test¶
Visuals tests are test files which have
-visual at the end of their
filename, before the extension. There is nothing needed in them to
make them work.
They should follow the [general test guidelines](general guidelines), especially noting the requirement to be self-describing (i.e., they must give a clear pass condition in their rendering).
Similarly, they should consider the rendering test guidelines, especially those about color, to ensure those running the test don’t incorrectly judge its result.