How to make RxJava threading run instantly in JUnit/Robolectric tests

README.md

Make RxJava Execute Immediately for JUnit Tests

BaseTestClass.java

public class BaseTestClass {
  
  
  @Before
  public void setup() {
        ShadowLog.stream = System.out;
        
        RxJavaTestPlugins.resetPlugins();
        RxJavaTestPlugins.getInstance().registerSchedulersHook(new RxJavaSchedulersHook() {
            @Override
            public Scheduler getIOScheduler() {
                return Schedulers.immediate();
            }

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

RxJavaTestPlugins.java

public class RxJavaTestPlugins extends RxJavaPlugins {
    RxJavaTestPlugins() {
        super();
    }

    public static void resetPlugins(){
        getInstance().reset();
    }
}