JavaTest is a test harness, JUnit is a test format. JavaTest is created to manage test suites written in many different formats, JUnit is a specific format and API for test development. The comparison is invalid, it would be more appropriate to compare JUnit API with one of test APIs, included into JavaTest's core libraries or its extensions.

Test format that is traditionally associated with this harness is the one that is used in most of Java Technology Compatibility Kits (TCK), based on test meta data provided in html form and Test/MultiTest API. Check the previous article for example of how JavaTest's Test Description looks like in .html. Comparing to JUnit, the java code of the TCK test may look like this:

The choice of the test API with explicit return for both positive and negative test conditions was driven by its use in TCKs, test suites, that are used for certification. One reason is requirement to be able to provide maximum to evaluate test failures offline without access to the implementation, where test failure is reproduced. Because of this there 'log' API is used instead of 'System.out', there is a special class Status that holds additional information other then pass/fail indication. Another reason is that TCK tests verify specific assertions of the specification and action of qualifying test as Passed need to be concise.

The JTReg is a JavaTest with set of plugins tuned for JDK regression testing. As opposite to the primary JavaTest use as a test harness for certification test suites, like TCK, where main requirements come from the test suite end user, JTReg is targeted to JDK developers. Main goals here are easiness to write and execute a test, support for major test types, possibility to execute shell scripts, adoption to the JDK development process. As you can see, there API for JDK regression tests is even simpler. See also JTReg FAQ for comments about JUnit support in JavaTest and JTReg.

Overall, different needs and different uses result in different test formats, that can be supported with single test harness.