private final ExecutorService executorService = Executors.newSingleThreadExecutor();

  private void subscribeToUpdates() {
    this.disposable.add(
        StepsUpdate
            .observeOn(Schedulers.from(executorService))
            .subscribe(
                l -> {
                  Timber.d("Current step updated to: %s", l);
                }));
  }

I am subscribing to StepsUpdate that emit steps when updated this code working fine.

public class CurrStepCloudEmitterTest {

  private CurrStepCloudEmitter currStepCloudEmitter;
  private PublishSubject<String> StepsUpdate;
  private static MockedStatic<Timber> mockTimber;
  private ExecutorService mockExecutorService;
  private TestScheduler testScheduler;

  @Before
  public void init() {
    recipeStepsUpdate = PublishSubject.create();
    mockExecutorService = Executors.newSingleThreadExecutor();
    testScheduler = new TestScheduler();
    RxJavaPlugins.setComputationSchedulerHandler(mockExecutorService -> testScheduler);
    RxJavaPlugins.setIoSchedulerHandler(mockExecutorService -> testScheduler);
    RxJavaPlugins.setNewThreadSchedulerHandler(mockExecutorService -> testScheduler);
    RxJavaPlugins.setSingleSchedulerHandler(mockExecutorService -> testScheduler);
    mockTimber = mockStatic(Timber.class);
  }

  @After
  public void tearDown() {
    mockTimber.close();
    mockExecutorService.shutdownNow();
    RxJavaPlugins.reset();
  }

  @Test
  public void subscribeToStepUpdate()
      throws InterruptedException {

    CurrStepCloudEmitter =
        new currStepCloudEmitter(StepsUpdate,
 "66a72db19c828d00180c5750");

    StepsUpdate.onNext("1");

    testScheduler.triggerActions();

    mockTimber.verify(() -> Timber.d("Current step updated to: %s", "1"), times(1));
  }

this is the test I am writing but giving error as

Wanted but not invoked:
Timber.class.d(
    "Current step updated to: %s",
    "1"
);
-> at timber.log.Timber.d(Timber.java:38)
Actually, there were zero interactions with this mock.

I debug it and there is a problem with schedular only I don’t know how to test the executive service.I thought of attaching the executorService Schedulers to test schedulers but it didn’t work.Can you guys help me with the test how I can test the subscribeToUpdates.