The tests are documented in a GitHub repository. To run the test, or to see any comments relating to the results, click on the link in the left-most column.
This page summarises results for interactive tests related to text alignment & justification. It complements the Styling initials section of the Language Enablement Index.
The tests themselves are linked to and described in a set of GitHub issues. Follow the links to the issue to run the test, or to see notes on the results (especially where the test only partially passes).
If you are developing a gap-analysis document, these tests can be set up very quickly, and the results captured simply. You can easily add tests to this list. See the instructions for further information. There is also a list of all tests and results pages.