@Test
public void overrideInitIoSchedulerCrashes() {

    // fail when Callable is null
    try {
        RxJavaPlugins.initIoScheduler(null);
        fail("Should have thrown NullPointerException");
    } catch (NullPointerException npe) {
        assertEquals("Scheduler Callable can't be null", npe.getMessage());
    }
    // fail when Callable result is null
    try {
        RxJavaPlugins.initIoScheduler(nullResultCallable);
        fail("Should have thrown NullPointerException");
    } catch (NullPointerException npe) {
        assertEquals("Scheduler Callable result can't be null", npe.getMessage());
    }
}