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/*
* Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.coroutines.flow
import kotlinx.coroutines.*
import kotlinx.coroutines.channels.*
import kotlin.test.*
class StateFlowTest : TestBase() {
@Test
fun testNormalAndNull() = runTest {
expect(1)
val state = MutableStateFlow<Int?>(0)
val job = launch(start = CoroutineStart.UNDISPATCHED) {
expect(2)
assertFailsWith<CancellationException> {
state.collect { value ->
when (value) {
0 -> expect(3)
1 -> expect(5)
null -> expect(8)
2 -> expect(10)
else -> expectUnreached()
}
}
}
expect(12)
}
expect(4) // collector is waiting
state.value = 1 // fire in the hole!
assertEquals(1, state.value)
yield()
expect(6)
state.value = 1 // same value, nothing happens
yield()
expect(7)
state.value = null // null value
assertNull(state.value)
yield()
expect(9)
state.value = 2 // another value
assertEquals(2, state.value)
yield()
expect(11)
job.cancel()
yield()
finish(13)
}
@Test
fun testEqualsConflation() = runTest {
expect(1)
val state = MutableStateFlow(Data(0))
val job = launch(start = CoroutineStart.UNDISPATCHED) {
expect(2)
assertFailsWith<CancellationException> {
state.collect { value ->
when (value.i) {
0 -> expect(3) // initial value
2 -> expect(5)
4 -> expect(7)
else -> error("Unexpected $value")
}
}
}
expect(9)
}
state.value = Data(1) // conflated
state.value = Data(0) // equals to last emitted
yield() // no repeat zero
state.value = Data(3) // conflated
state.value = Data(2) // delivered
expect(4)
yield()
state.value = Data(2) // equals to last one, dropped
yield()
state.value = Data(5) // conflated
state.value = Data(4) // delivered
expect(6)
yield()
expect(8)
job.cancel()
yield()
finish(10)
}
data class Data(val i: Int)
@Test
fun testDataModel() = runTest {
val s = CounterModel()
launch {
val sum = s.counter.take(11).sum()
assertEquals(55, sum)
}
repeat(10) {
yield()
s.inc()
}
}
class CounterModel {
// private data flow
private val _counter = MutableStateFlow(0)
// publicly exposed as a flow
val counter: StateFlow<Int> get() = _counter
fun inc() {
_counter.value++
}
}
@Test
public fun testOnSubscriptionWithException() = runTest {
expect(1)
val state = MutableStateFlow("A")
state
.onSubscription {
emit("collector->A")
state.value = "A"
}
.onSubscription {
emit("collector->B")
state.value = "B"
throw TestException()
}
.onStart {
emit("collector->C")
state.value = "C"
}
.onStart {
emit("collector->D")
state.value = "D"
}
.onEach {
when (it) {
"collector->D" -> expect(2)
"collector->C" -> expect(3)
"collector->A" -> expect(4)
"collector->B" -> expect(5)
else -> expectUnreached()
}
}
.catch { e ->
assertTrue(e is TestException)
expect(6)
}
.launchIn(this)
.join()
assertEquals(0, state.subscriptionCount.value)
finish(7)
}
@Test
fun testOperatorFusion() {
val state = MutableStateFlow(String)
assertSame(state, (state as Flow<*>).cancellable())
assertSame(state, (state as Flow<*>).distinctUntilChanged())
assertSame(state, (state as Flow<*>).flowOn(Dispatchers.Default))
assertSame(state, (state as Flow<*>).conflate())
assertSame(state, state.buffer(Channel.CONFLATED))
assertSame(state, state.buffer(Channel.RENDEZVOUS))
}
@Test
fun testResetUnsupported() {
val state = MutableStateFlow(42)
assertFailsWith<UnsupportedOperationException> { state.resetReplayCache() }
assertEquals(42, state.value)
assertEquals(listOf(42), state.replayCache)
}
@Test
fun testUpdate() = runTest {
val state = MutableStateFlow(0)
state.update { it + 2 }
assertEquals(2, state.value)
state.update { it + 3 }
assertEquals(5, state.value)
}
}
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