ServiceManager serviceManager = new ServiceManager(asList(a, b));
    serviceManager.startAsync().awaitHealthy();
    ImmutableMap<Service, Duration> startupTimes = serviceManager.startupDurations();
    assertThat(startupTimes).hasSize(2);
    assertThat(startupTimes.get(a)).isAtLeast(Duration.ofMillis(150));
    assertThat(startupTimes.get(b)).isAtLeast(Duration.ofMillis(353));
  }