时钟
简介
准确模拟时间相关行为对于验证应用程序的正确性至关重要。时钟功能的利用使开发人员能够在测试中操纵和控制时间,从而能够精确验证渲染时间、超时、计划任务等功能,而无需实时执行的延迟和可变性。
时钟 API 提供了以下方法来控制时间:
setFixedTime
:为Date.now()
和new Date()
设置固定时间。install
:初始化时钟并允许你pauseAt
:在特定时间暂停时间。fastForward
:快进时间。runFor
:让时间运行特定时长。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。如果这不适用于您的用例,您可以使用 install
,它允许您稍后暂停时间、快进时间、滴答时间等。setSystemTime
仅推荐用于高级用例。
注意
Page.clock() 会覆盖与时间相关的原生全局类和函数,从而允许手动控制它们。
Date
setTimeout
clearTimeout
setInterval
clearInterval
requestAnimationFrame
cancelAnimationFrame
requestIdleCallback
cancelIdleCallback
performance
Event.timeStamp
警告
如果在测试中的任何时候调用 install
,则此调用必须发生在任何其他与时钟相关的调用之前(请参阅上面列表中的注释)。按错误顺序调用这些方法将导致未定义的行为。例如,您不能先调用 setInterval
,然后是 install
,再是 clearInterval
,因为 install
会覆盖时钟函数的原生定义。
使用预定义时间进行测试
通常,你只需要伪造 Date.now
,同时让计时器继续运行。这样时间会自然流动,但 Date.now
总是返回一个固定值。
<div id="current-time" data-testid="current-time"></div>
<script>
const renderTime = () => {
document.getElementById('current-time').textContent =
new Date().toLocaleString();
};
setInterval(renderTime, 1000);
</script>
SimpleDateFormat format = new SimpleDateFormat("yyy-MM-dd'T'HH:mm:ss");
page.clock().setFixedTime(format.parse("2024-02-02T10:00:00"));
page.navigate("https://:3333");
Locator locator = page.getByTestId("current-time");
assertThat(locator).hasText("2/2/2024, 10:00:00 AM");
page.clock().setFixedTime(format.parse("2024-02-02T10:30:00"));
// We know that the page has a timer that updates the time every second.
assertThat(locator).hasText("2/2/2024, 10:30:00 AM");
一致的时间和计时器
有时你的计时器依赖于 Date.now
,当 Date.now
的值不随时间变化时会感到困惑。在这种情况下,你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://: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");
测试不活动监控
不活动监控是 Web 应用程序中的常见功能,它会在一段时间不活动后将用户注销。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://: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();
手动滴答计时,一致地触发所有计时器
在极少数情况下,你可能希望手动按步进时间,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://: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");