时钟

简介

准确模拟依赖时间的行为对于验证应用程序的正确性至关重要。利用Clock功能，开发人员可以在测试中操作和控制时间，从而能够精确验证诸如渲染时间、超时、计划任务等功能，而无需实时执行带来的延迟和可变性。

Clock API 提供以下方法来控制时间

• setFixedTime：为 Date.now() 和 new Date() 设置固定时间。
• install：初始化时钟并允许您
  • pauseAt：在特定时间暂停时间。
  • fastForward：快进时间。
  • runFor：运行指定持续时间的时间。
  • resume：恢复时间。
• setSystemTime：设置当前系统时间。

推荐的方法是使用 setFixedTime 将时间设置为特定值。如果这对于您的用例不起作用，您可以使用 install，它允许您稍后暂停时间、快进时间、使其前进等。setSystemTime 仅推荐用于高级用例。

注意

Page.clock() 覆盖了与时间相关的原生全局类和函数，允许手动控制它们

• Date
• setTimeout
• clearTimeout
• setInterval
• clearInterval
• requestAnimationFrame
• cancelAnimationFrame
• requestIdleCallback
• cancelIdleCallback
• performance
• Event.timeStamp

使用预定义时间进行测试

通常您只需要伪造 Date.now 并保持计时器运行即可。这样，时间就会自然流逝，但 Date.now 始终返回固定值。

<div id="current-time" data-testid="current-time"></div>
<script>
  const renderTime = () => {
    document.getElementById('current-time').textContent =
        new Date().toLocaleString();
  };
  setInterval(renderTime, 1000);
</script>

一致的时间和计时器

有时您的计时器依赖于 Date.now，并且当 Date.now 值不随时间变化时会感到困惑。在这种情况下，您可以在测试时安装时钟并快进到感兴趣的时间。

<div id="current-time" data-testid="current-time"></div>
<script>
  const renderTime = () => {
    document.getElementById('current-time').textContent =
        new Date().toLocaleString();
  };
  setInterval(renderTime, 1000);
</script>

// Initialize clock with some time before the test time and let the page load
// naturally. `Date.now` will progress as the timers fire.
SimpleDateFormat format = new SimpleDateFormat("yyy-MM-dd'T'HH:mm:ss");
page.clock().install(new Clock.InstallOptions().setTime(format.parse("2024-02-02T08:00:00")));
page.navigate("https://127.0.0.1:3333");
Locator locator = page.getByTestId("current-time");

// Pretend that the user closed the laptop lid and opened it again at 10am.
// Pause the time once reached that point.
page.clock().pauseAt(format.parse("2024-02-02T10:00:00"));

// Assert the page state.
assertThat(locator).hasText("2/2/2024, 10:00:00 AM");

// Close the laptop lid again and open it at 10:30am.
page.clock().fastForward("30:00");
assertThat(locator).hasText("2/2/2024, 10:30:00 AM");

测试空闲状态监控

空闲状态监控是 Web 应用程序中的一项常见功能，它会在用户一段时间内处于非活动状态后注销用户。测试此功能可能很棘手，因为您需要等待很长时间才能看到效果。借助时钟，您可以加快时间并快速测试此功能。

<div id="remaining-time" data-testid="remaining-time"></div>
<script>
  const endTime = Date.now() + 5 * 60_000;
  const renderTime = () => {
    const diffInSeconds = Math.round((endTime - Date.now()) / 1000);
    if (diffInSeconds <= 0) {
      document.getElementById('remaining-time').textContent =
        'You have been logged out due to inactivity.';
    } else {
      document.getElementById('remaining-time').textContent =
        `You will be logged out in ${diffInSeconds} seconds.`;
    }
    setTimeout(renderTime, 1000);
  };
  renderTime();
</script>
<button type="button">Interaction</button>

// Initial time does not matter for the test, so we can pick current time.
page.clock().install();
page.navigate("https://127.0.0.1:3333");
Locator locator = page.getByRole("button");

// Interact with the page
locator.click();

// Fast forward time 5 minutes as if the user did not do anything.
// Fast forward is like closing the laptop lid and opening it after 5 minutes.
// All the timers due will fire once immediately, as in the real browser.
page.clock().fastForward("05:00");

// Check that the user was logged out automatically.
assertThat(page.getByText("You have been logged out due to inactivity.")).isVisible();

手动逐时推进，一致地触发所有计时器

在极少数情况下，您可能希望手动逐时推进，在此过程中触发所有计时器和动画帧，以实现对时间流逝的细粒度控制。

<div id="current-time" data-testid="current-time"></div>
<script>
  const renderTime = () => {
    document.getElementById('current-time').textContent =
        new Date().toLocaleString();
  };
  setInterval(renderTime, 1000);
</script>

SimpleDateFormat format = new SimpleDateFormat("yyy-MM-dd'T'HH:mm:ss");
// Initialize clock with a specific time, let the page load naturally.
page.clock().install(new Clock.InstallOptions()
    .setTime(format.parse("2024-02-02T08:00:00")));
page.navigate("https://127.0.0.1:3333");
Locator locator = page.getByTestId("current-time");

// Pause the time flow, stop the timers, you now have manual control
// over the page time.
page.clock().pauseAt(format.parse("2024-02-02T10:00:00"));
assertThat(locator).hasText("2/2/2024, 10:00:00 AM");

// Tick through time manually, firing all timers in the process.
// In this case, time will be updated in the screen 2 times.
page.clock().runFor(2000);
assertThat(locator).hasText("2/2/2024, 10:00:02 AM");

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