RE: what's an "Unrooted Test" and why can't I find anything online about
In case somebody still has this problem (I ran into this as well - JUnit4, no use of TestCase at all).
If you extend a class and the supre class has a @BeforeClass method and and exception occures in the @BeforeClass method that isn't caught (or logged) you might get this 'Unrooted Test' error.
(Note: if you put a breakpoint in the @BeforeClass method and run your test in debug mode subsequent test runs will behave as expected (and also report on the thrown error.)
Hope it helps somebody out there...