Scheduling a periodic task using ScheduledExecutorService.

AppConfig.java

@Configuration
public class AppConfig {
    @Bean
    public ScheduledExecutorService getScheduledExecutorService() {
        return Executors.newSingleThreadScheduledExecutor();
    }
}

SomeReloadService.java

@Component
public class SomeReloadService {
    @Autowired
    private ScheduledExecutorService executor;

    @Autowired
    private SomeDependency someDependency;

    /**
     * Schedule some task here.
     */
    public void scheduleSomeReloadTask() {
        executor.scheduleAtFixedRate(() -> {
          // Your task.
          someDependency.doSomething();
        }, 0, 1, TimeUnit.DAYS);
    }
}

SomeReloadServiceTest.java

public class SomeReloadServiceTest {
    @Mock
    private ScheduledExecutorService executor;

    @Mock
    private SomeDependency someDependency;

    @InjectMocks
    private SomeReloadService someReloadService;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void testScheduleSomeReloadTask(){
        // Given
        final ArgumentCaptor<Runnable> argumentCaptor = ArgumentCaptor.forClass(Runnable.class);

        // When
        someReloadService.scheduleSomeReloadTask();

        // Then
        Mockito.verify(executor, Mockito.times(1)).scheduleAtFixedRate(argumentCaptor.capture(), Mockito.eq(0l), Mockito.eq(1l), Mockito.eq(TimeUnit.DAYS));
        argumentCaptor.getAllValues().get(0).run();
        Mockito.verify(someDependency, Mockito.times(1)).doSomething();
    }
}