Coroutines Best Practices

Question 1

How should I use dispatcher in classes?

Answer 1

Don't hardcode dispatcher in the class rather we should inject it in the constructor.
Benefits- It will make unit and instrumentation testing easier.

Question 2

Which layer should create coroutines in Android app?

Answer 2

The ViewModel/Presenter layer should create coroutines.
Benefits- The UI layer should be dumb and not directly trigger any business logic.
Instead, it should defer that responsibility to the ViewModel/Presenter layer. Testing the UI layer requires instrumentation tests in Android which needs an emulator to run.

Question 3

Where should suspend functions create in Android project?

Answer 3

The layer below the ViewModel/Presenter should expose suspend functions and Flows.
Benefits- The caller generally the viewmodel layer can control the execution and lifecycle of the work happening in those layers, being able to cancel when needed.

Question 4

How to execute coroutines during the lifetime of application?

Answer 4

Create a scope in Application class of Android.

class MyApplication : Application() {
  // No need to cancel this scope as it'll be torn down with the process
  val applicationScope = CoroutineScope(SupervisorJob() + otherConfig)
}