Class: Clock

Updates the clock to automatically advance time.

With this mode, the clock advances to the first scheduled timer and fires it, in a loop. Between each timer, it will also break the event loop, allowing any scheduled promise callbacks to execute before running the next one.

This mode allows tests to be authored in a way that does not need to be aware of the mock clock. Consequently, tests which have been authored without a mock clock installed can one with auto tick enabled without any other updates to the test logic.

In many cases, this can greatly improve test execution speed because asynchronous tasks will execute as quickly as possible rather than waiting real time to complete.

Furthermore, tests can be authored in a consitent manner. They can always be written in an asynchronous style rather than having tick sprinkled throughout the tests with mock time in order to manually advance the clock.

When auto tick is enabled, tick can still be used to synchronously advance the clock if necessary.

Install the mock clock over the built-in methods.

Instruct the installed Clock to also mock the date returned by new Date()

Tick the Clock forward, running any enqueued timeouts along the way

Uninstall the mock clock, returning the built-in methods to their places.

Execute a function with a mocked Clock

The clock will be installed before the function is called and uninstalled in a finally after the function completes.