RxJavaSchedulersTestRule.java

public class RxJavaSchedulersTestRule implements TestRule {
  @Override
  public Statement apply(final Statement base, Description description) {
    return new Statement() {
      @Override
      public void evaluate() throws Throwable {
        resetPlugins();
        RxJavaPlugins.getInstance().registerSchedulersHook(new TestRxJavaSchedulersHook());
        RxAndroidPlugins.getInstance().registerSchedulersHook(new TestRxAndroidSchedulersHook());

        base.evaluate();

        resetPlugins();
      }
    };
  }

  private void resetPlugins() {
    RxJavaPlugins.getInstance().reset();
    RxAndroidPlugins.getInstance().reset();
  }

  private class TestRxAndroidSchedulersHook extends RxAndroidSchedulersHook {
    @Override
    public Scheduler getMainThreadScheduler() {
      return Schedulers.immediate();
    }
  }

  private class TestRxJavaSchedulersHook extends RxJavaSchedulersHook {
    @Override
    public Scheduler getIOScheduler() {
      return Schedulers.immediate();
    }
  }
}