I was able to convert three tests in derbynet to run via HarnessJavaTest. The problems with the other tests are mentioned in the javadoc for the test. Forking the VM seemed to be a problem in most cases, at least running from within Eclipse, because the forked VM would not have the correct classpath. Attaching patch for review. Note that BadConnectionTest is commented out in _Suite in this patch, as I have a separate patch for converting the very simple bad connection test.