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Coroutines support libraries for Kotlin
/*
* Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.coroutines
import kotlinx.coroutines.internal.*
import kotlinx.coroutines.scheduling.*
import org.junit.*
import java.io.*
import java.util.*
import java.util.concurrent.atomic.*
import kotlin.coroutines.*
import kotlin.test.*
private val VERBOSE = systemProp("test.verbose", false)
/**
* Is `true` when running in a nightly stress test mode.
*/
public actual val isStressTest = System.getProperty("stressTest")?.toBoolean() ?: false
public actual val stressTestMultiplierSqrt = if (isStressTest) 5 else 1
private const val SHUTDOWN_TIMEOUT = 1_000L // 1s at most to wait per thread
public actual val isNative = false
/**
* Multiply various constants in stress tests by this factor, so that they run longer during nightly stress test.
*/
public actual val stressTestMultiplier = stressTestMultiplierSqrt * stressTestMultiplierSqrt
@Suppress("ACTUAL_WITHOUT_EXPECT")
public actual typealias TestResult = Unit
/**
* Base class for tests, so that tests for predictable scheduling of actions in multiple coroutines sharing a single
* thread can be written. Use it like this:
*
* ```
* class MyTest : TestBase() {
* @Test
* fun testSomething() = runBlocking { // run in the context of the main thread
* expect(1) // initiate action counter
* launch { // use the context of the main thread
* expect(3) // the body of this coroutine in going to be executed in the 3rd step
* }
* expect(2) // launch just scheduled coroutine for execution later, so this line is executed second
* yield() // yield main thread to the launched job
* finish(4) // fourth step is the last one. `finish` must be invoked or test fails
* }
* }
* ```
*/
public actual open class TestBase(private var disableOutCheck: Boolean) {
actual constructor(): this(false)
public actual val isBoundByJsTestTimeout = false
private var actionIndex = AtomicInteger()
private var finished = AtomicBoolean()
private var error = AtomicReference()
// Shutdown sequence
private lateinit var threadsBefore: Set
private val uncaughtExceptions = Collections.synchronizedList(ArrayList())
private var originalUncaughtExceptionHandler: Thread.UncaughtExceptionHandler? = null
/*
* System.out that we redefine in order to catch any debugging/diagnostics
* 'println' from main source set.
* NB: We do rely on the name 'previousOut' in the FieldWalker in order to skip its
* processing
*/
private lateinit var previousOut: PrintStream
/**
* Throws [IllegalStateException] like `error` in stdlib, but also ensures that the test will not
* complete successfully even if this exception is consumed somewhere in the test.
*/
@Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
public actual fun error(message: Any, cause: Throwable? = null): Nothing {
throw makeError(message, cause)
}
public fun hasError() = error.get() != null
private fun makeError(message: Any, cause: Throwable? = null): IllegalStateException =
IllegalStateException(message.toString(), cause).also {
setError(it)
}
private fun setError(exception: Throwable) {
error.compareAndSet(null, exception)
}
private fun printError(message: String, cause: Throwable) {
setError(cause)
println("$message: $cause")
cause.printStackTrace(System.out)
println("--- Detected at ---")
Throwable().printStackTrace(System.out)
}
/**
* Throws [IllegalStateException] when `value` is false like `check` in stdlib, but also ensures that the
* test will not complete successfully even if this exception is consumed somewhere in the test.
*/
public inline fun check(value: Boolean, lazyMessage: () -> Any) {
if (!value) error(lazyMessage())
}
/**
* Asserts that this invocation is `index`-th in the execution sequence (counting from one).
*/
public actual fun expect(index: Int) {
val wasIndex = actionIndex.incrementAndGet()
if (VERBOSE) println("expect($index), wasIndex=$wasIndex")
check(index == wasIndex) { "Expecting action index $index but it is actually $wasIndex" }
}
/**
* Asserts that this line is never executed.
*/
public actual fun expectUnreached() {
error("Should not be reached, current action index is ${actionIndex.get()}")
}
/**
* Asserts that this is the last action in the test. It must be invoked by any test that used [expect].
*/
public actual fun finish(index: Int) {
expect(index)
check(!finished.getAndSet(true)) { "Should call 'finish(...)' at most once" }
}
/**
* Asserts that [finish] was invoked
*/
public actual fun ensureFinished() {
require(finished.get()) { "finish(...) should be caller prior to this check" }
}
public actual fun reset() {
check(actionIndex.get() == 0 || finished.get()) { "Expecting that 'finish(...)' was invoked, but it was not" }
actionIndex.set(0)
finished.set(false)
}
private object TestOutputStream : PrintStream(object : OutputStream() {
override fun write(b: Int) {
error("Detected unexpected call to 'println' from source code")
}
})
fun println(message: Any?) {
if (disableOutCheck) kotlin.io.println(message)
else previousOut.println(message)
}
@Before
fun before() {
initPoolsBeforeTest()
threadsBefore = currentThreads()
originalUncaughtExceptionHandler = Thread.getDefaultUncaughtExceptionHandler()
Thread.setDefaultUncaughtExceptionHandler { t, e ->
println("Exception in thread $t: $e") // The same message as in default handler
e.printStackTrace()
uncaughtExceptions.add(e)
}
if (!disableOutCheck) {
previousOut = System.out
System.setOut(TestOutputStream)
}
}
@After
fun onCompletion() {
// onCompletion should not throw exceptions before it finishes all cleanup, so that other tests always
// start in a clear, restored state
if (actionIndex.get() != 0 && !finished.get()) {
makeError("Expecting that 'finish(${actionIndex.get() + 1})' was invoked, but it was not")
}
// Shutdown all thread pools
shutdownPoolsAfterTest()
// Check that are now leftover threads
runCatching {
checkTestThreads(threadsBefore)
}.onFailure {
setError(it)
}
// Restore original uncaught exception handler
Thread.setDefaultUncaughtExceptionHandler(originalUncaughtExceptionHandler)
if (!disableOutCheck) {
System.setOut(previousOut)
}
if (uncaughtExceptions.isNotEmpty()) {
makeError("Expected no uncaught exceptions, but got $uncaughtExceptions")
}
// The very last action -- throw error if any was detected
error.get()?.let { throw it }
}
fun initPoolsBeforeTest() {
DefaultScheduler.usePrivateScheduler()
}
fun shutdownPoolsAfterTest() {
DefaultScheduler.shutdown(SHUTDOWN_TIMEOUT)
DefaultExecutor.shutdownForTests(SHUTDOWN_TIMEOUT)
DefaultScheduler.restore()
}
@Suppress("ACTUAL_WITHOUT_EXPECT", "ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
public actual fun runTest(
expected: ((Throwable) -> Boolean)? = null,
unhandled: List<(Throwable) -> Boolean> = emptyList(),
block: suspend CoroutineScope.() -> Unit
): TestResult {
var exCount = 0
var ex: Throwable? = null
try {
runBlocking(block = block, context = CoroutineExceptionHandler { _, e ->
if (e is CancellationException) return@CoroutineExceptionHandler // are ignored
exCount++
when {
exCount > unhandled.size ->
printError("Too many unhandled exceptions $exCount, expected ${unhandled.size}, got: $e", e)
!unhandled[exCount - 1](e) ->
printError("Unhandled exception was unexpected: $e", e)
}
})
} catch (e: Throwable) {
ex = e
if (expected != null) {
if (!expected(e))
error("Unexpected exception: $e", e)
} else
throw e
} finally {
if (ex == null && expected != null) error("Exception was expected but none produced")
}
if (exCount < unhandled.size)
error("Too few unhandled exceptions $exCount, expected ${unhandled.size}")
}
protected inline fun assertFailsWith(block: () -> Unit): T {
val result = runCatching(block)
assertTrue(result.exceptionOrNull() is T, "Expected ${T::class}, but had $result")
return result.exceptionOrNull()!! as T
}
protected suspend fun currentDispatcher() = coroutineContext[ContinuationInterceptor]!!
}