how would i write a unit test for that? because as soon as i run this in runBlocking{} in the test doSomething() will be called on the same thread.

It will not be called in the same thread in test. By default,

async { ... }

uses

CommonPool

dispatcher and

doSomething

will be executed in that another thread.

but we actually want it running in the same thread. can i tell async that it should use the same thread?

You can specify the context for async explicitly if you need it.

ok so just use unconfined to run it in the same thread?

Unconfined

runs in the same thread only until the first suspension point.

runBlocking is just what we use in the test suite

So, if you want it to run in `UI' thread in production, then you use

async(UI) { … }

and for tests you make UI injectable and use

coroutineContext

that’s available inside

runBlocking