Skip to main content

Clock

Accurately simulating time-dependent behavior is essential for verifying the correctness of applications. Learn more about clock emulation.

Note that clock is installed for the entire BrowserContext, so the time in all the pages and iframes is controlled by the same clock.

fast_forward​

def fast_forward(ticks)

Advance the clock by jumping forward in time. Only fires due timers at most once. This is equivalent to user closing the laptop lid for a while and reopening it later, after given time.

Usage

example_aa1d7ed6650f37a2ef8a00945f0f328896eae665418b6758a9e24fcc4c7bcd83.py
page.clock.fast_forward(1000)
page.clock.fast_forward("30:00")

install​

def install(time: nil)

Install fake implementations for the following time-related functions:

  • Date
  • setTimeout
  • clearTimeout
  • setInterval
  • clearInterval
  • requestAnimationFrame
  • cancelAnimationFrame
  • requestIdleCallback
  • cancelIdleCallback
  • performance

Fake timers are used to manually control the flow of time in tests. They allow you to advance time, fire timers, and control the behavior of time-dependent functions. See Clock#run_for and Clock#fast_forward for more information.

run_for​

def run_for(ticks)

Advance the clock, firing all the time-related callbacks.

Usage

example_ce3b9a2e3e9e37774d4176926f5aa8ddf76d8c2b3ef27d8d8f82068dd3720a48.py
page.clock.run_for(1000);
page.clock.run_for("30:00")

pause_at​

def pause_at(time)

Advance the clock by jumping forward in time and pause the time. Once this method is called, no timers are fired unless Clock#run_for, Clock#fast_forward, Clock#pause_at or Clock#resume is called.

Only fires due timers at most once. This is equivalent to user closing the laptop lid for a while and reopening it at the specified time and pausing.

Usage

example_e3bfa88ff84efbef1546730c2046e627141c6cd5f09c54dc2cf0e07cbb17c0b5.py
page.clock.pause_at(datetime.datetime(2020, 2, 2))
page.clock.pause_at("2020-02-02")

resume​

def resume

Resumes timers. Once this method is called, time resumes flowing, timers are fired as usual.

set_fixed_time​

def set_fixed_time(time)

alias: fixed_time=

Makes Date.now and new Date() return fixed fake time at all times, keeps all the timers running.

Usage

example_612285ca3970e44df82608ceff6f6b9ae471b0f7860b60916bbaefd327dd2ffd.py
page.clock.set_fixed_time(datetime.datetime.now())
page.clock.set_fixed_time(datetime.datetime(2020, 2, 2))
page.clock.set_fixed_time("2020-02-02")

set_system_time​

def set_system_time(time)

alias: system_time=

Sets current system time but does not trigger any timers.

Usage

example_1f707241c9dfcb70391f40269feeb3e50099815e43b9742bba738b72defae04f.py
page.clock.set_system_time(datetime.datetime.now())
page.clock.set_system_time(datetime.datetime(2020, 2, 2))
page.clock.set_system_time("2020-02-02")