elapse method

void elapse (Duration duration)

Simulates the asynchronous passage of time.

This should only be called from within the zone used by run.

If duration is negative, the returned future completes with an ArgumentError.

If a previous call to elapse has not yet completed, throws a StateError.

Any Timers created within the zone used by run which are to expire at or before the new time after duration has elapsed are run. The microtask queue is processed surrounding each timer. When a timer is run, the clock will have been advanced by the timer's specified duration. Calls to elapseBlocking from within these timers and microtasks which cause the clock to elapse more than the specified duration, can cause more timers to expire and thus be called.

Once all expired timers are processed, the clock is advanced (if necessary) to the time this method was called + duration.

Implementation 

void elapse(Duration duration);