common/kotlinx-coroutines-core-common/test/WithContextTest.kt

/*
 * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

@file:Suppress("NAMED_ARGUMENTS_NOT_ALLOWED") // KT-21913

package kotlinx.coroutines.experimental

import kotlin.coroutines.experimental.*
import kotlin.test.*

class WithContextTest : TestBase() {

    @Test
    fun testSameContextNoSuspend() = runTest {
        expect(1)
        launch(coroutineContext) { // make sure there is not early dispatch here
            finish(5) // after main exits
        }
        expect(2)
        val result = withContext(coroutineContext) { // same context!
            expect(3) // still here
            "OK"
        }
        assertEquals("OK", result)
        expect(4)
        // will wait for the first coroutine
    }

    @Test
    fun testSameContextWithSuspend() = runTest {
        expect(1)
        launch(coroutineContext) { // make sure there is not early dispatch here
            expect(4)
        }
        expect(2)
        val result = withContext(coroutineContext) { // same context!
            expect(3) // still here
            yield() // now yields to launch!
            expect(5)
            "OK"
        }
        assertEquals("OK", result)
        finish(6)
    }

    @Test
    fun testCancelWithJobNoSuspend() = runTest {
        expect(1)
        launch(coroutineContext) { // make sure there is not early dispatch to here
            finish(6) // after main exits
        }
        expect(2)
        val job = Job()
        val result = withContext(coroutineContext + job) { // same context + new job
            expect(3) // still here
            job.cancel() // cancel out job!
            try {
                yield() // shall throw CancellationException
                expectUnreached()
            } catch (e: CancellationException) {
                expect(4)
            }
            "OK"
        }
        assertEquals("OK", result)
        expect(5)
        // will wait for the first coroutine
    }

    @Test
    fun testCancelWithJobWithSuspend() = runTest {
        expect(1)
        launch(coroutineContext) { // make sure there is not early dispatch to here
            expect(4)
        }
        expect(2)
        val job = Job()
        val result = withContext(coroutineContext + job) { // same context + new job
            expect(3) // still here
            yield() // now yields to launch!
            expect(5)
            job.cancel() // cancel out job!
            try {
                yield() // shall throw CancellationException
                expectUnreached()
            } catch (e: CancellationException) {
                expect(6)
            }
            "OK"
        }
        assertEquals("OK", result)
        finish(7)
    }

    @Test
    fun testRunCancellableDefault() = runTest(
        expected = { it is JobCancellationException }
    ) {
        val job = Job()
        job.cancel() // cancel before it has a chance to run
        withContext(job + wrapperDispatcher(coroutineContext)) {
            expectUnreached() // will get cancelled
        }
    }

    @Test
    fun testRunAtomicTryCancel() = runTest {
        expect(1)
        val job = Job()
        job.cancel() // try to cancel before it has a chance to run

        try {
            withContext(job + wrapperDispatcher(coroutineContext), CoroutineStart.ATOMIC) {
                require(isActive)
                // but start atomically
                expect(2)
                yield() // but will cancel here
                expectUnreached()
            }
        } catch (e: JobCancellationException) {
            // This block should be invoked *after* context body
            finish(3)
        }
    }

    @Test
    fun testRunUndispatchedTryCancel() = runTest(
        expected = { it is JobCancellationException }
    ) {
        expect(1)
        val job = Job()
        job.cancel() // try to cancel before it has a chance to run
        withContext(job + wrapperDispatcher(coroutineContext), CoroutineStart.UNDISPATCHED) { // but start atomically
            require(isActive)
            finish(2)
            yield() // but will cancel here
            expectUnreached()
        }
    }

    @Test
    fun testRunSelfCancellationWithException() = runTest {
        expect(1)
        var job: Job? = null
        job = launch(coroutineContext) {
            try {
                expect(3)
                withContext(wrapperDispatcher(coroutineContext)) {
                    require(isActive)
                    expect(5)
                    require(job!!.cancel()) // cancel itself
                    require(!job!!.cancel(AssertionError())) // cancel again, no success here
                    require(!isActive)
                    throw TestException() // but throw a different exception
                }
            } catch (e: Throwable) {
                expect(7)
                // make sure TestException, not CancellationException or AssertionError is thrown
                assertTrue(e is TestException, "Caught $e")
            }
        }
        expect(2)
        yield() // to the launched job
        expect(4)
        yield() // again to the job
        expect(6)
        yield() // again to exception handler
        finish(8)
    }

    @Test
    fun testRunSelfCancellation() = runTest {
        expect(1)
        var job: Job? = null
        job = launch(coroutineContext) {
            try {
                expect(3)
                withContext(wrapperDispatcher(coroutineContext)) {
                    require(isActive)
                    expect(5)
                    require(job!!.cancel()) // cancel itself
                    require(!job!!.cancel(AssertionError())) // cancel again, no success here
                    require(!isActive)
                }
            } catch (e: Throwable) {
                expect(7)
                // make sure TestException, not CancellationException or AssertionError is thrown!
                assertTrue(e is JobCancellationException, "Caught $e")
            }
        }

        expect(2)
        yield() // to the launched job
        expect(4)
        yield() // again to the job
        expect(6)
        yield() // again to exception handler
        finish(8)
    }

    private fun wrapperDispatcher(context: CoroutineContext): CoroutineContext {
        val dispatcher = context[ContinuationInterceptor] as CoroutineDispatcher
        return object : CoroutineDispatcher() {
            override fun dispatch(context: CoroutineContext, block: Runnable) {
                dispatcher.dispatch(context, block)
            }
        }
    }

    private class TestException : Exception()
}