How do I unit test a singleton launching a never e...

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[Daniele Segato]

How do I unit test a singleton launching a never ending coroutine?

class MySingleton(private val scope: CoroutineScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)) {
  init {
    scope.launch {
      neverEndingCoroutineHere()
    }
  }
}

The singleton already take a parameter for launching stuff in a scope.

When I test I give it the TestCouroutineScope created by runBlockingTest so tests fails with

kotlinx.coroutines.test.UncompletedCoroutinesError: Test finished with active jobs: ["coroutine#63":StandaloneCoroutine{Active}@1cec6f46]

I do not want to add a destroy() function in my singleton, it makes no sense other than for testing.
And I don't want to cancel the TestCouroutineScope either cause that check for unfinished jobs is actually very usuful.

My solution for now is to duplicate the scope in my singleton

class MySingleton(
  private val scope: CoroutineScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
  private val permanentScope: CoroutineScope = scope
) {
  init {
    permanentScope.launch {
      neverEndingCoroutineHere()
    }
  }
}

and from my tests I give

permanentScope = CoroutineScope(SupervisorJob() + TestCoroutineDispatcher())

and cancel that in @After which means never ending jobs like the one above run outside of the TestCoroutineScope

Is there a better way?