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時鐘

簡介​

準確模擬時間依賴行為對於驗證應用程式的正確性至關重要。利用 Clock 功能允許開發人員在測試中操縱和控制時間，從而精確驗證渲染時間、超時、排程任務等功能，而不會有即時執行的延遲和變異性。

Clock API 提供以下方法來控制時間:

  • setFixedTime: 設定 Date.now() 和 new Date() 的固定時間。
  • install: 初始化時鐘並允許你:
    • pauseAt: 在特定時間暫停時間。
    • fastForward: 快進時間。
    • runFor: 執行特定時間段。
    • resume: 恢復時間。
  • setSystemTime: 設定當前系統時間。

建議的方法是使用 setFixedTime 將時間設置為特定值。如果這不適用於您的使用案例，您可以使用 install，這允許您稍後暫停時間、快進時間、滴答時間等。setSystemTime 只建議用於高級使用案例。

note

Page.clock() 覆蓋了與時間相關的原生全域類別和函式，允許手動控制它們:

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

測試預定時間​

通常你只需要偽造 Date.now 同時保持計時器運行。這樣時間會自然流動，但 Date.now 總是返回一個固定值。

<div id="current-time" data-testid="current-time"></div>
<script>
  const renderTime = () => {
    document.getElementById('current-time').textContent =
        new Date().toLocaleString();
  };
  setInterval(renderTime, 1000);
</script>
await page.clock.setFixedTime(new Date('2024-02-02T10:00:00'));
await page.goto('http://localhost:3333');
await expect(page.getByTestId('current-time')).toHaveText('2/2/2024, 10:00:00 AM');

await page.clock.setFixedTime(new Date('2024-02-02T10:30:00'));
// We know that the page has a timer that updates the time every second.
await expect(page.getByTestId('current-time')).toHaveText('2/2/2024, 10:30:00 AM');

一致的時間和計時器​

有時候你的計時器依賴 Date.now，當 Date.now 的值隨時間不變時會感到困惑。在這種情況下，你可以安裝時鐘並快進到測試時感興趣的時間。

<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.
await page.clock.install({ time: new Date('2024-02-02T08:00:00') });
await page.goto('http://localhost:3333');

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

// Assert the page state.
await expect(page.getByTestId('current-time')).toHaveText('2/2/2024, 10:00:00 AM');

// Close the laptop lid again and open it at 10:30am.
await page.clock.fastForward('30:00');
await expect(page.getByTestId('current-time')).toHaveText('2/2/2024, 10:30:00 AM');

測試非活動監控​

在網頁應用程式中，不活動監控是一個常見的功能，會在一段時間不活動後將使用者登出。測試這個功能可能會很棘手，因為你需要等待很長時間才能看到效果。借助時鐘，你可以加速時間並快速測試這個功能。

<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.
await page.clock.install();
await page.goto('http://localhost:3333');
// Interact with the page
await page.getByRole('button').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.
await page.clock.fastForward('05:00');

// Check that the user was logged out automatically.
await expect(page.getByText('You have been logged out due to inactivity.')).toBeVisible();

手動計時，持續觸發所有計時器​

在少數情況下，您可能希望手動調整時間，觸發所有計時器和動畫幀，以實現對時間流逝的精細控制。

<div id="current-time" data-testid="current-time"></div>
<script>
  const renderTime = () => {
    document.getElementById('current-time').textContent =
        new Date().toLocaleString();
  };
  setInterval(renderTime, 1000);
</script>
// Initialize clock with a specific time, let the page load naturally.
await page.clock.install({ time: new Date('2024-02-02T08:00:00') });
await page.goto('http://localhost:3333');

// Pause the time flow, stop the timers, you now have manual control
// over the page time.
await page.clock.pauseAt(new Date('2024-02-02T10:00:00'));
await expect(page.getByTestId('current-time')).toHaveText('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.
await page.clock.runFor(2000);
await expect(page.getByTestId('current-time')).toHaveText('2/2/2024, 10:00:02 AM');

相關影片​