scheduler

Accessor for the underlying TestCoroutineScheduler, which controls the current time.

Delay-skipping behavior is implemented by this dispatcher. Only delay calls within this dispatcher can be skipped and can advance the virtual time. That is, using code like withContext(Dispatchers.IO) { … } overrides the dispatcher and disables delay-skipping for the entire block.

Sometimes, you may need to instantiate a service within your tests, that you want to internally use delay-skipping. In these situations, you may need to pass the scheduler:

test("Test a cron service") {
   val cron = CronService(coroutineContext = time.scheduler)
   var witness = false

   cron.runIn(2.minutes) { witness = true }

   check(witness == false)
   delay(2.minutes)
   check(witness == true)
}

If the service expects a CoroutineScope, see foregroundScope and backgroundScope instead.