.containsExactlyInAnyOrder(a1, a2)
    assertThat(dispatcher.queuedCalls()).isEmpty()

    // Let the calls finish.
    waiting.countDown()
    t1.join()
    t2.join()

    // Now we should have 0 running calls and 0 queued calls.
    assertThat(dispatcher.runningCallsCount()).isEqualTo(0)
    assertThat(dispatcher.queuedCallsCount()).isEqualTo(0)
    assertThat(dispatcher.runningCalls()).isEmpty()