This directory contains test that rely in internal testing APIs as well as legacy tests, which should be migrated to WPT over time (or simply removed if we have the equivalent coverage in WPT). When fixing a test flake in this directory subtree, consider migrating to WPT if here only for legacy reasons.
Please avoid adding new tests to this directory or any of its sub-folders. New tests should be authored in WPT with few exceptions. The following guidelines may be useful for choosing where to place a test:
Exceptions to authoring in WPT are when an internal testing API is needed or testing Chromium specific behavior (e.g. compositor thread). Before adding a new internal API or adding a test based on an existing testing API, check if a similar problem has been solved in a WPT test. For example, the functionality in the internal animation pause API is fully replaceable with web-animation API calls that are supported on all browsers.
Please refer to README.md files in these WPT directories for more help on writing effective tests.
In some cases, multiple folders may seem appropriate (e.g. a scroll-driven transform), though even in these cases, one category may be more central to the test (common theme across sub-tests). If the sub-tests feel too disjoint to fall into a single category, then consider breaking into multiple tests.