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androidunit-testingkotlin-coroutines

Android testing of Kotlin coroutines with TestCoroutineDispatcher (deprecated) alternative


im investigating testing of coroutines in my Android application and following this code lab Advanced Android in Kotlin 05.3: Testing Coroutines and Jetpack integrations

this codelab contains the following code snippet

@ExperimentalCoroutinesApi
val testDispatcher: TestCoroutineDispatcher = TestCoroutineDispatcher()

@ExperimentalCoroutinesApi
@Before
fun setupDispatcher() {
    Dispatchers.setMain(testDispatcher)
}

@ExperimentalCoroutinesApi
@After
fun tearDownDispatcher() {
    Dispatchers.resetMain()
    testDispatcher.cleanupTestCoroutines()
}

however TestCoroutineDispatcher is marked as deprecated with this comment:-

/**
 * [CoroutineDispatcher] that performs both immediate and lazy execution of coroutines in tests
 * and uses a [TestCoroutineScheduler] to control its virtual clock.
 *
 * By default, [TestCoroutineDispatcher] is immediate. That means any tasks scheduled to be run without delay are
 * immediately executed. If they were scheduled with a delay, the virtual clock-time must be advanced via one of the
 * methods on the dispatcher's [scheduler].
 *
 * When switched to lazy execution using [pauseDispatcher] any coroutines started via [launch] or [async] will
 * not execute until a call to [DelayController.runCurrent] or the virtual clock-time has been advanced via one of the
 * methods on [DelayController].
 *
 * @see DelayController
 */
@Deprecated("The execution order of `TestCoroutineDispatcher` can be confusing, and the mechanism of " +
    "pausing is typically misunderstood. Please use `StandardTestDispatcher` or `UnconfinedTestDispatcher` instead.",
    level = DeprecationLevel.WARNING)
// Since 1.6.0, ERROR in 1.7.0 and removed as experimental in 1.8.0
public class TestCoroutineDispatcher(public override val scheduler: TestCoroutineScheduler = TestCoroutineScheduler()):
    TestDispatcher(), Delay, SchedulerAsDelayController
{...}

It is not clear how I should use the suggested alternatives to TestCoroutineDispatcher() are StandardTestDispatcher and UnconfinedTestDispatcher straight replacements for TestCoroutineDispatcher()?

what am I missing?


Solution

  • Seems it is possible to use more elegant solution like runTest() since 1.6.0

    Taken from this SO answer

    See the documentation for details on how to use the module.