kotlin/libraries/stdlib/test/concurrent/TimerTest.kt

@file:kotlin.jvm.JvmVersion
package test.concurrent

import java.util.*
import kotlin.concurrent.*
import kotlin.test.*

import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit
import java.util.concurrent.TimeoutException


class TimerTest {
    @Test fun scheduledTask() {
        val timer = Timer()

        val latch = CountDownLatch(10)
        val startedAt = System.nanoTime()
        lateinit var callbackTask: TimerTask
        val task = timer.scheduleAtFixedRate(100, 10) {
            callbackTask = this
            latch.countDown()
            if (latch.count == 0L) this.cancel()
        }
        if (!latch.await(1500, TimeUnit.MILLISECONDS)) throw TimeoutException()
        val elapsed = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startedAt)

        val expectedRange = 100L..500L
        assertTrue(elapsed in expectedRange, "Expected elapsed ($elapsed ms) to fit in range $expectedRange")
        assertSame(task, callbackTask)
    }
}