I'd like to Unit Test the following class :

class MyClass(private val scope: CoroutineScope) {
     // launches new coroutines in the passed scope 
}

Some of my test scenarios requires that the passed

CoroutineScope

be cancelled. How would you write such test with

runBlockingTest

?

Could you create a dummy class which implements CoroutineScope that just creates a job for its context and immediately cancels it? You may be able to attach its job as a child of the coroutine scope of runBlockingTest

I ended up writing this function :

fun TestCoroutineScope.runInScope(block: suspend CoroutineScope.() -> Unit) {
    val job = launch(block = block)
    advanceUntilIdle()
    job.cancel()
}

The passed

block

is executing eagerly due to

runBlockingTest

, advances until idle then cancel the scope. This should be enough to simulate the lifecycle of a child

CoroutineScope

. I wonder if such thing is possible with existing constructs, for example

coroutineScope { ...}

.