ATF is ServiceNow’s automatic testing framework. Like all the ServiceNow tools, it’s OK. These are some notes, in no particular order, on ATF.
Tests should be named something that makes sense, and include a description of what the test does in the main test record.
Tests should not rely on data that is specific to the system. If specific things are needed by a test (such as associated records, users, or anything else) the test should create it.
For testing users/roles/permissions (which is a must) create the user with the proper role(s) in the test.
You can specify the role when creating the user, and this makes moving tests across systems much easier, and anyone that has to maintain the test (including the author) will be much happier.