Hi what is the right way to kick off an async task but then

Question

Hi what is the right way to kick off an async task but then immediately return with the result of my original operation ```suspend fun callback suspend fun execute request Request Response val response = callback return response ```

Endre Deak · Answer

I mean is it just as simple as this sample above

streetsofboston · Answer

No this does not return immediately Instead you may want to change your execute function `fun CoroutineScope execute request Request callback suspend gt Unit val response Response = launch callback return response `

Endre Deak · Answer

thanks

Endre Deak · Answer

fwiw the syntax above causes warningns in ide so instead it s something like ```suspend fun execute request Request callback suspend gt Unit Response = withContext Dispatchers Default val response Response = launch callback response ```

Endre Deak · Answer

how can I write a unit test that verifies the execution order

Nick Allen · Answer

What you wrote is the same as if you didn t launch at all and just called callback directly guessing you just missed suspend at beginning or it won t compile `withContext` will wait for all child coroutines to finish read up on structured concurrency for why In general it s not a great idea to have a suspend function that returns before it s finished all the work it started Usually a method is either suspend or it takes a CoroutineScope somehow usually not both What warnings in ide did you get Is the ` ` stuff suspending code

Nick Allen · Answer

See <https kotlin github io kotlinx coroutines kotlinx coroutines test > for help testing coroutines In general you can t test order when launching because launching doesn t really guarantee order It may run immediately or later or at the same time If you care about order then you need to force things to run in the order you want If you just want to test it doesn t wait then you can give a callback that waits for a signal like `val job = Job job join ` and check that the other function returns without giving the signal `job complete `

Endre Deak · Answer

thanks for the feedback will rethink this again