kotlin-coroutines-flows

Convert a cold Flow to StateFlow using stateIn with viewModelScope, SharingStarted.WhileSubscribed(5000), and an initial value. This keeps the upstream active for 5 seconds after the last subscriber leaves, surviving configuration changes.

Wrap async calls inside a coroutineScope block and await their results. This gives structured concurrency where all children complete or cancel together, unlike launching separate unstructured jobs.

StateFlow holds a current value and suits UI state, while SharedFlow is for one-time events like snackbars or navigation. Use MutableSharedFlow exposed as SharedFlow for effects collected in a LaunchedEffect.

Dispatchers.IO is JVM and Android only. In KMP, use Dispatchers.Default or Dispatchers.Main which are available on all platforms, or provide the IO dispatcher via dependency injection.

Use runTest and call .test on the StateFlow, then assert each awaitItem in emission order. Combine with advanceUntilIdle and fake repositories backed by MutableStateFlow to control emitted values.

GlobalScope launches coroutines with no structured cancellation, causing leaks when the lifecycle owner is destroyed. Use viewModelScope in ViewModels or LaunchedEffect in composables so work is cancelled automatically.