Spring - How to test Controller with ApplicationEventPublisher dependency? - spring

Question

I have a Controller which is publishing an event
#RestController
public class Controller
{
#Autowired
private ApplicationEventPublisher publisher;
#GetMapping("/event")
public void get()
{
publisher.publishEvent(new Event());
}
}
Now I want to test that the event is published. First I tried to #MockBean the ApplicationEventPublisher and verify the method call. But this does not work according to https://jira.spring.io/browse/SPR-14335
So I am doing it like this:
#RunWith(SpringRunner.class)
#WebMvcTest(controllers = Controller.class)
public class ControllerTest
{
#Autowired
private MockMvc mockMvc;
#Test
public void getTest() throws Exception
{
this.mockMvc.perform(get("/").contentType(MediaType.APPLICATION_JSON)
.andExpect(status().isOk());
assertNotNull(Listener.event);
}
#TestConfiguration
static class Listener
{
public static Event event;
#EventListener
void listen ( Event incoming )
{
event = incoming;
}
}
}
Is there an easier way for this common use case?

Answer 1

You can do it like this
#RunWith(SpringRunner.class)
public class ControllerTest {
private MockMvc mockMvc;
#MockBean
private ApplicationEventPublisher publisher;
#Before
public void setup() {
Controller someController= new Controller(publisher);
mockMvc = MockMvcBuilders.standaloneSetup(someController).build();
}
#Test
public void getTest() throws Exception
{
ArgumentCaptor<Event> argumentCaptor = ArgumentCaptor.forClass(Event.class);
doAnswer(invocation -> {
Event value = argumentCaptor.getValue();
//assert if event is correct
return null;
}).when(publisher).publishEvent(argumentCaptor.capture());
this.mockMvc.perform(get("/").contentType(MediaType.APPLICATION_JSON))
.andExpect(status().isOk());
verify(publisher, times(1)).publishEvent(any(Event.class));
}
}
And also change Field Injection to Constructor Injection in your controller class(It is a good practice).
#RestController
public class Controller
{
private ApplicationEventPublisher publisher;
#Autowired
public Controller(ApplicationEventPublisher publisher) {
this.publisher = publisher;
}
....
}

Answer 2

im facing the same problem, and for now i solve the problem using TestConfiguration:
#SpringBootTest
class MyUseCaseIT {
#Autowired private ApplicationEventPublisher publisher;
#Autowired private MyService service;
#Test
void callUseCase() {
var event = mock(MyEvent.class);
doNothing().when(publisher).publishEvent(event);
service.useCase();
verify(publisher).publishEvent(event);
}
#TestConfiguration
static class MockitoPublisherConfiguration {
#Bean
#Primary
ApplicationEventPublisher publisher() {
return mock(ApplicationEventPublisher.class);
}
}

Answer 3

Another possiblity would be that you replace the ApplicationEventPublisher instance on your controller with the mock instance using reflection in your test:
public class ControllerTest {
...
// Collect your controller
#Autowired
private Controller controller;
// Use the mock publisher
#MockBean
private ApplicationEventPublisher publisherMock;
// E.g. in setup set the mock publisher on your controller
#Before
public void setup() {
ReflectionTestUtils.setField(controller, "publisher", publisherMock);
}
...