TestCoroutineScheduler: Make it a TimeSource

[hfhbd]

Already todo, and is very useful to avoid manually increasing TestTimeSource
Use case:
testing timebased caching, timed retries, windowing, date time apis (using Clock)

class TimeCache(val timeSource: TimeSource = TimeSource.Monotonic, val valid: Duration = 1.seconds) {
    private var counter = 0
    private var cache: Data? = null

    suspend fun get(): Data {
        if (cache != null && cache!!.requestAt.elapsedNow() < valid) {
            return cache!!
        }
        cache = null
        return requestServer().also {
            cache = it
        }
    }

    private suspend fun requestServer(): Data {
        delay(3.seconds)
        return Data(counter.also { counter += 1 }, timeSource.markNow())
    }
}

data class Data(val data: Int, val requestAt: TimeMark)

@Test
fun blockingImprecise() = runBlocking {
    val cache = TimeCache()
    assertEquals(0, cache.get().data)
    delay(2.seconds)
    assertEquals(1, cache.get().data)
    delay(0.5.seconds)
    assertEquals(1, cache.get().data)
}

@Test
fun blockingManuallyPrecise() = runBlocking {
    val ts = TestTimeSource()
    val cache = TimeCache(ts)
    assertEquals(0, cache.get().data)
    delay(2.seconds)
    ts += 2.seconds
    assertEquals(1, cache.get().data)
    delay(0.5.seconds)
    ts += 0.5.seconds
    assertEquals(1, cache.get().data)
}

@Test
fun skippingManuallyPrecise() = runTest {
    val ts = TestTimeSource()
    val cache = TimeCache(ts)
    assertEquals(0, cache.get().data)
    delay(2.seconds)
    ts += 2.seconds
    assertEquals(1, cache.get().data)
    delay(0.5.seconds)
    ts += 0.5.seconds
    assertEquals(1, cache.get().data)
}

@Test
fun expectedPrecise() = runTest {
    val cache = TimeCache(timeSource)
    assertEquals(0, cache.get().data)
    delay(2.seconds)
    assertEquals(1, cache.get().data)
    delay(0.5.seconds)
    assertEquals(1, cache.get().data)
}

private val TestScope.timeSource: TimeSource get() = object : AbstractLongTimeSource(DurationUnit.MILLISECONDS) {
    override fun read(): Long = currentTime
}

[dkhalanskyjb]

Fixed in 1.6.0-RC3.