content: package <%= appPackage %>.util;
  
  import org.junit.rules.TestRule;
  import org.junit.runner.Description;
  import org.junit.runners.model.Statement;
  
  import java.util.concurrent.Callable;
  
  import io.reactivex.Scheduler;
  import io.reactivex.android.plugins.RxAndroidPlugins;
  import io.reactivex.functions.Function;
  import io.reactivex.plugins.RxJavaPlugins;
  import io.reactivex.schedulers.Schedulers;
  
  /**
   * NOTE: You MUST use this rule in every test class that targets app code that uses RxJava. Even
   * when that code doesn't use any scheduler. The RxJava {@link Schedulers} class is setup once and
   * caches the schedulers in memory. So if one of the test classes doesn't use this rule by the time
   * this rule runs it may be too late to override the schedulers. This is really not ideal but
   * currently there isn't a better approach. More info here:
   * https://github.com/ReactiveX/RxJava/issues/2297
   * <p>
   * <p>This rule registers SchedulerHooks for RxJava and RxAndroid to ensure that subscriptions
   * always subscribeOn and observeOn Schedulers.immediate(). Warning, this rule will reset
   * RxAndroidPlugins and RxJavaPlugins before and after each test so if the application code uses
   * RxJava plugins this may affect the behaviour of the testing method.
   */
  public class RxSchedulersOverrideRule implements TestRule {
  
      public final Scheduler SCHEDULER_INSTANCE = Schedulers.trampoline();
      private Function<Scheduler, Scheduler> mSchedulerFunction = scheduler -> SCHEDULER_INSTANCE;
      private Function<Callable<Scheduler>, Scheduler> schedulerFunctionLazy =
              schedulerCallable -> SCHEDULER_INSTANCE;
  
      @Override
      public Statement apply(final Statement base, Description description) {
          return new Statement() {
              @Override
              public void evaluate() throws Throwable {
                  RxAndroidPlugins.reset();
                  RxAndroidPlugins.setInitMainThreadSchedulerHandler(schedulerFunctionLazy);
  
                  RxJavaPlugins.reset();
                  RxJavaPlugins.setIoSchedulerHandler(mSchedulerFunction);
                  RxJavaPlugins.setNewThreadSchedulerHandler(mSchedulerFunction);
                  RxJavaPlugins.setComputationSchedulerHandler(mSchedulerFunction);
  
                  base.evaluate();
  
                  RxAndroidPlugins.reset();
                  RxJavaPlugins.reset();
              }
          };
      }
  }
  