So yes, I tried and code inside

async

only runs when I call

await

async

isnt’ lazy, but it is… asynchronous (shocker). So if you check immediately after calling your

registerDevice

whether the

registerDeviceForService

method has been called on

lib

, then it likely won’t be the case. A new thread is spawned, so you have to wait for the method to be called on that thread.

@Martin Devillers

async

does not spawn a new thread

@louiscad true, it dispatches to the common pool, so to a different thread…

@Martin Devillers It's not necessarily a different thread either

So how do you guys test

async

methods? I thought wrapping test into

runBlocking

solves the problem

The problem is with your mock response here. You have two options: - Set up the mock to wait until its method is called, do something then - Set up the mock so that it answers some predefined value once it’s called, without trying to verify immediately that it has been called

@aaverin I don't write methods that return a

Deferred

. I use

suspend fun

instead. I use

async

for parallel coroutines execution, not in place of

suspend fun

or

launch

. If you really need to return a

Deferred

, be sure to follow the recommendations here: https://github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md#async-style-functions and use

await()

to await your

Deferred

inside your coroutine launched inside

runBlocking

What if you know for sure that this function will, eg, go to network, and has to be async? Sometimes you don’t want to pass threading decision to a consumer of the function

@aaverin

async

is still not the right solution in this case. Have you read this guide? https://github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md If not, you should

well,

resume

will be called only if I will have chance to mock the response The way it usually works with RxJava, you call the method, then you catch callback on a mocked instance, and manually call that callback methods to simulate successful network response

I don't use objects mocking right now, so I can't tell you

thus my original question – how to test methods with

suspendCoroutine

?

I don’t see any problem. You call this method (probably for tests easiest way to wrap this call to runBlocking), you check result of this method