/
FlowAssert.kt
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/
FlowAssert.kt
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/*
* Copyright (C) 2018 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.squareup.sqldelight.runtime.coroutines
import kotlinx.coroutines.CancellationException
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.Job
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.channels.Channel.Factory.UNLIMITED
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.launch
import kotlinx.coroutines.withTimeout
@ExperimentalCoroutinesApi
suspend fun <T> Flow<T>.test(timeoutMs: Long = 1000L, validate: suspend FlowAssert<T>.() -> Unit) {
coroutineScope {
val events = Channel<Event<T>>(UNLIMITED)
val collectJob = launch {
val terminalEvent = try {
collect { item ->
events.send(Event.Item(item))
}
Event.Complete
} catch (_: CancellationException) {
null
} catch (t: Throwable) {
Event.Error(t)
}
if (terminalEvent != null) {
events.send(terminalEvent)
}
events.close()
}
val flowAssert = FlowAssert(events, collectJob, timeoutMs)
val ensureConsumed = try {
flowAssert.validate()
true
} catch (e: CancellationException) {
if (e !== ignoreRemainingEventsException) {
throw e
}
false
}
if (ensureConsumed) {
flowAssert.expectNoMoreEvents()
}
}
}
private val ignoreRemainingEventsException = CancellationException("Ignore remaining events")
internal sealed class Event<out T> {
object Complete : Event<Nothing>()
data class Error(val throwable: Throwable) : Event<Nothing>()
data class Item<T>(val item: T) : Event<T>()
}
class FlowAssert<T> internal constructor(
private val events: Channel<Event<T>>,
private val collectJob: Job,
private val timeoutMs: Long
) {
private suspend fun <T> withTimeout(body: suspend () -> T): T {
return if (timeoutMs == 0L) {
body()
} else {
withTimeout(timeoutMs) {
body()
}
}
}
fun cancel() {
collectJob.cancel()
}
fun cancelAndIgnoreRemainingEvents(): Nothing {
cancel()
throw ignoreRemainingEventsException
}
fun expectNoEvents() {
val event = events.poll()
if (event != null) {
throw AssertionError("Expected no events but found $event")
}
}
suspend fun expectNoMoreEvents() {
val event = withTimeout {
events.receiveOrNull()
}
if (event != null) {
throw AssertionError("Expected no more events but found $event")
}
}
suspend fun expectItem(): T {
val event = withTimeout {
events.receive()
}
if (event !is Event.Item<T>) {
throw AssertionError("Expected item but was $event")
}
return event.item
}
suspend fun expectComplete() {
val event = withTimeout {
events.receive()
}
if (event != Event.Complete) {
throw AssertionError("Expected complete but was $event")
}
}
suspend fun expectError(): Throwable {
val event = withTimeout {
events.receive()
}
if (event !is Event.Error) {
throw AssertionError("Expected error but was $event")
}
return event.throwable
}
}