java -jar HtmlUnitTestrunner.jar <URL to unit test page>
If you want to run a unit test from your filesystem, just use a file:// URL.
6 tests, 15 assertions, 0 failures, 0 errors
The general result will also be communicated via the program exit code (0 = success, 1 = failure).
HtmlUnitTestrunner was tested successfully even on complex JS files including the rather large ExtJS framework, for instance.