```class TestExample class Example var counter Int = 0 fun s kotlinlang #coroutines

class TestExample {

    class Example {
        var counter: Int = 0

        fun startCounter() {
            val coroutineScope = CoroutineScope(Dispatchers.Unconfined)

            coroutineScope.launch {
                while (counter <= 100) {
                    counter += 1
                    delay(100)
                }
            }
        }
    }

    @Test
    fun `test 1`() = runBlockingTest {
        val example = Example()
        example.startCounter()
        Assert.assertEquals(1, example.counter)
        advanceTimeBy(150)    // fails
        // Thread.sleep(150) // works
        Assert.assertEquals(2, example.counter)
    }
}

Paulius Ruminas

09/13/2019, 12:59 PM

You override the coroutine test scope

val coroutineScope = CoroutineScope(Dispatchers.Unconfined)

so you must wait for 100ms.

myanmarking

09/13/2019, 12:59 PM

what do you mean ?

Paulius Ruminas

09/13/2019, 1:02 PM

class Example {
        var counter: Int = 0

        suspend fun startCounter(scope: CoroutineScope) {
            scope.launch {
                while (counter <= 100) {
                    counter++
                    delay(100)
                }
            }
        }
    }

    @Test
    fun `test 1`() = runBlockingTest {
        val example = Example()
        example.startCounter(this@runBlockingTest)
        Assert.assertEquals(1, example.counter)
        advanceTimeBy(150)
        Assert.assertEquals(2, example.counter)
    }

runBlockingTest

creates a coroutine scope for running tests

val scope = TestCoroutineScope(safeContext)

. If you do not reuse this scope then you don't have a virtual clock anymore and you actually have to wait for the specified delay.

myanmarking

09/13/2019, 1:10 PM

i'll try the suggestion. thanks!

it works. thanks! is there any way to make it work with the original code ?

gergo

09/13/2019, 1:38 PM

not really, only if you inject the Dispatcher or the CoroutineScope or the delay value so you can switch it out in the test

myanmarking

09/13/2019, 1:39 PM

hm, in case i inject the CoroutineScope, won't multiple function calls use the same scope instance ? i'm not sure about this semantics

gergo

09/13/2019, 1:41 PM

yes they would, but i don't see when this would be an issue for you

If you really want new scope every time and inject the scope, then you could inject a factory like

class Example(private val coroutineScopeFactory : () -> CoroutineScope = { CoroutineScope(Dispatchers.Unconfined) })

... then in test you could swich it out like

Example{ this@runBlockingTest }

in your method would look like

val coroutineScope = coroutineScopeFactory()

myanmarking

09/13/2019, 1:45 PM

ya, thanks

3 Views

#coroutines Join Slack