rspec/rules/S6313/kotlin/rule.adoc

== Why is this an issue?

Views should not be responsible for directly triggering coroutines. Hence, `ViewModel` classes should prefer creating coroutines instead of exposing suspending functions to perform some piece of business logic. This allows for easier testing of your application, as `ViewModel` classes can be unit tested, whereas views require instrumentation tests.

Please refer to the https://developer.android.com/kotlin/coroutines/coroutines-best-practices#viewmodel-coroutines[Android docs] for more advanced examples and mechanisms of updating the views with data generated asynchronously.

This rule raises an issue when suspending functions are exposed by classes inheriting from `ViewModel`.

=== Noncompliant code example

[source,kotlin]
----
class MyViewModel : ViewModel() {
    suspend fun performAction() = suspendingWorker()
}
----

=== Compliant solution

[source,kotlin]
----
class MyViewModel : ViewModel() {
    fun performAction() =
        viewModelScope.launch {
            suspendingWorker()
        }
}
----

== Resources

* https://developer.android.com/kotlin/coroutines/coroutines-best-practices#viewmodel-coroutines[The ViewModel should create coroutines] (Android coroutines best practices)