code: @Test public void shouldBeFasterWhenRunningMultipleSlowTasks() throws Exception {
    final Collection<Callable<Void>> callables=new ArrayList<Callable<Void>>();
    final long delay=100;
    final int times=10;
    for (int i=0; i < times; i++) {
      callables.add(createSlowCallable(delay));
    }
    final long start=System.currentTimeMillis();
    victim.submit(callables);
    final long end=System.currentTimeMillis();
    final long delta=end - start;
    LOG.debug("Execution took: {}",delta);
    assertTrue(delta < delay * times);
  }
  