Android testing RxJava 2

Question

Having an error when testing RxJava code. It fils when I call AndroidSchedulers.mainThread() in ViewModel. Does anyone know how to deal with it?

Here is my stack trace:

java.lang.ExceptionInInitializerError
    ...
    at com.cardsimulator.ui.MainViewModel.executeCommand(MainViewModel.java:56)
    at com.cardsimulator.ui.MainViewModelTest.testExecuteCommand_NormalCommand(MainViewModelTest.java:54)
    ...
Caused by: java.lang.RuntimeException: Method getMainLooper in android.os.Looper not mocked. See http://g.co/androidstudio/not-mocked for details.

GVillani82 · Accepted Answer · 2018-12-17 13:49:25Z

1

You should not use AndroidSchedulers.mainThead() for testing purpose. You can use Schedulers.trampoline() instead. It basically executes all the tasks on the current thread without any queueing and the timed overloads use blocking sleep as well.

You can use injection framework (as Dagger 2) for injecting the right scheduler. Or simply you can add this in your test:

@BeforeClass
public static void setupTest() {
    RxAndroidPlugins.setInitMainThreadSchedulerHandler(
            __ -> Schedulers.trampoline());
}

edited Dec 17, 2018 at 13:49

answered Dec 17, 2018 at 13:27

GVillani82

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