public int getDepth(Throwable ex) {
        return getDepth(ex.getClass(), 0);
    }
@Test
    public void ancestry() {
        RollbackRule rr = new RollbackRule(java.lang.Exception.class.getName());
        // Exception -> Runtime -> MyRuntimeException
        assertThat(rr.getDepth(new MyRuntimeException(""))).isEqualTo(2);
    }