RxAndroidTestSchedulerHook and RxJavaTestSchedulerHook as TestRule

RxSchedulersOverrideRule.java

public class RxSchedulersOverrideRule implements TestRule {

    private final RxJavaSchedulersHook mRxJavaSchedulersHook = new RxJavaSchedulersHook() {
        @Override
        public Scheduler getIOScheduler() {
            return Schedulers.immediate();
        }

        @Override
        public Scheduler getNewThreadScheduler() {
            return Schedulers.immediate();
        }
    };

    private final RxAndroidSchedulersHook mRxAndroidSchedulersHook = new RxAndroidSchedulersHook() {
        @Override
        public Scheduler getMainThreadScheduler() {
            return Schedulers.immediate();
        }
    };

    // Hack to get around RxJavaPlugins.reset() not being public
    // See https://github.com/ReactiveX/RxJava/issues/2297
    // Hopefully the method will be public in new releases of RxAndroid and we can remove the hack.
    private void callResetViaReflectionIn(RxJavaPlugins rxJavaPlugins)
            throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {
        Method method = rxJavaPlugins.getClass().getDeclaredMethod("reset");
        method.setAccessible(true);
        method.invoke(rxJavaPlugins);
    }

    @Override
    public Statement apply(final Statement base, Description description) {
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                RxAndroidPlugins.getInstance().reset();
                RxAndroidPlugins.getInstance().registerSchedulersHook(mRxAndroidSchedulersHook);
                callResetViaReflectionIn(RxJavaPlugins.getInstance());
                RxJavaPlugins.getInstance().registerSchedulersHook(mRxJavaSchedulersHook);

                base.evaluate();

                RxAndroidPlugins.getInstance().reset();
                callResetViaReflectionIn(RxJavaPlugins.getInstance());
            }
        };
    }
}