kotlin-flow

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

Issue	Resolution
Flow never emits	Add terminal operator (collect, first)
Stale data in UI	Use stateIn or shareIn properly

Usage

Skill("kotlin-flow")