Really basic question here but I feel like I'm finding a lot of out of date information. How can I ...

# coroutines

[Colton Idle]

Really basic question here but I feel like I'm finding a lot of out of date information.

How can I wait for a coroutine to finish in a test?

example:

@Test
fun `test network call`() {
    var response: Response<Projects>
    GlobalScope.async {
        response = service.getMostPopularProjects()
    }

    assertThat(response.body().popularProjectSize().toString()).isGreaterThan("1")
}

[Zach Klippenstein (he/him) [MOD]]

First, don’t use GlobalScope. I want to change the name of this channel to #coroutines-no-globalscope

[Zach Klippenstein (he/him) [MOD]]

I assume getMostPopularProjects is a suspend function? Use runBlocking, runBlockingTest, or one of the other coroutine testing facilities

[Colton Idle]

@Zach Klippenstein (he/him) [MOD] correct. getMost... is a suspend function.

I'm guessing there's no "right"/simple answer here since you said "`runBlocking`, runBlockingTest, or one of the other coroutine testing facilities"

[Zach Klippenstein (he/him) [MOD]]

You don’t need to tag people in channels they’ve replied to, they automatically get notified

[Zach Klippenstein (he/him) [MOD]]

runBlocking is probably the simplest answer, but the “right” answer depends on your needs.

[Colton Idle]

Sorry just habit to @ the person I'm speaking to! 😅

[Colton Idle]

Thanks. I'll look into that. Of course the 3 stack overflow questions on this didn't mention run blocking, they all mentioned await() which through me in a loop. Stumbled upon craig russels blog post that I'm reading through now https://craigrussell.io/2019/11/unit-testing-coroutine-suspend-functions-using-testcoroutinedispatcher/

[Zach Klippenstein (he/him) [MOD]]

Also if you don’t need a result, don’t use async, use launch

[Colton Idle]

For anyone following along. In my simple project I just added

testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.4.3")

and then did this

@Test
fun `test network call`() {
    var response: Response<Projects>
    runBlocking {
        response = service.getMostPopularProjects()
        assertThat(response.body().popularProjectSize().toString()).isGreaterThan("1")
    }
}

and everything seems to work as expected. No other setup! Thanks Zach!

[ephemient]

if you're just using runBlocking and aren't setting any test dispatchers or using runBlockingTest, you don't need kotlinx-coroutines-test

[Colton Idle]

I thought about that, but I removed the dependency and then runBlocking wasn't compiling anymore. I wonder if it's because it pulls in another coroutines dep transitively. I'll play around with it though. Thanks for letting me know.