name: kotlin-flow description: Kotlin Flow - StateFlow, SharedFlow, operators, testing version: "1.0.0" sasmp_version: "1.3.0" bonded_agent: 03-kotlin-coroutines bond_type: PRIMARY_BOND

execution: timeout_ms: 30000 retry: max_attempts: 3 backoff: exponential initial_delay_ms: 1000

parameters: required: - name: topic type: string validation: "^(basics|operators|hot_flows|testing)$" optional: - name: include_examples type: boolean default: true

logging: level: info events: [skill_invoked, topic_loaded, error_occurred]

Kotlin Flow Skill

Reactive programming with Kotlin Flow.

Topics Covered

Cold vs Hot Flows

// Cold Flow - starts fresh for each collector
fun loadData(): Flow<Data> = flow {
    emit(fetchData())
}

// Hot Flow - shared state
private val _state = MutableStateFlow(State())
val state: StateFlow<State> = _state.asStateFlow()

Flow Operators

fun searchUsers(query: Flow<String>): Flow<List<User>> =
    query
        .debounce(300)
        .filter { it.length >= 2 }
        .distinctUntilChanged()
        .flatMapLatest { term -> userRepository.search(term) }
        .catch { emit(emptyList()) }

Combining Flows

val dashboard: Flow<Dashboard> = combine(
    userFlow,
    ordersFlow,
    notificationsFlow
) { user, orders, notifications ->
    Dashboard(user, orders.size, notifications.count())
}

Testing with Turbine

@Test
fun `flow emits values`() = runTest {
    viewModel.state.test {
        assertThat(awaitItem().isLoading).isFalse()
        viewModel.load()
        assertThat(awaitItem().isLoading).isTrue()
        advanceUntilIdle()
        assertThat(awaitItem().data).isNotNull()
    }
}

Troubleshooting

Usage

Skill("kotlin-flow")