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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

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

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

page.clock.pause_at(Time.parse("2020-02-02"))
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.

Use this method for simple scenarios where you only need to test with a predefined time. For more advanced scenarios, use Clock#install instead. Read docs on clock emulation to learn more.

Usage

page.clock.set_fixed_time(Time.now)
page.clock.set_fixed_time(Time.parse("2020-02-02"))
page.clock.set_fixed_time("2020-02-02")

# or we can use the alias
page.clock.fixed_time = Time.now
page.clock.fixed_time = Time.parse("2020-02-02")
page.clock.fixed_time = "2020-02-02"

set_system_time​

def set_system_time(time)

alias: system_time=

Sets system time, but does not trigger any timers. Use this to test how the web page reacts to a time shift, for example switching from summer to winter time, or changing time zones.

Usage

page.clock.set_system_time(Time.now)
page.clock.set_system_time(Time.parse("2020-02-02"))
page.clock.set_system_time("2020-02-02")

# or we can use the alias
page.clock.system_time = Time.now
page.clock.system_time = Time.parse("2020-02-02")
page.clock.system_time = "2020-02-02"