Test Observable.FlatMap Mockito - java-8

Question

I've been looking on internet but haven't found the solution if any (new on UnitTest and Mockito)
It's possible to test a method that return a call of a service and manipulate it's result before to return it? Example;
public Observable<Reports> getUserReports(Integer userId) {
return serviceClient
.getReports(userId)
.flatMap(serviceReports -> {
System.out.println("Testing inside flatMap"); <- never reach this line therefore duno if methods down here are invoked and work perfectly
final Observable<List<Report>> reports = getPendingReports(userId, serviceReports);
//More methods that modify/update information
return zip(observable1, observable2, observable3
(report1, report2, report3) -> {
updateReports(otherArguments, report1, report2, report3);
return serviceReports;
});
});
}
So far I've tried;
#Test
public void myTest(){
when(serviceClient
.getReports(anyInt()))
.thenReturn(Observable.just(reports));
Observable<Reports> result = mocketClass.getUserReports(userId)
}
Tryed with Spy and Mock but no luck so far. Any hint or help would be great.

Answer 1

To mock getReports() behavior you need to mock the serviceClient firstly and pass it into your service class.
Just as example:
#Test
public void myTest(){
// Given
final ServiceClient mockedServiceClient = Mockito.mock(ServiceClient.class);
when(mockedServiceClient
.getReports(anyInt()))
.thenReturn(Observable.just(reports));
// and create an instance of your class under testing with injected mocked service client.
final MyUserService userService = new MyUserService();
userService.setServiceClient(mockedServiceClient);
// When run a method under test
Observable<Reports> actualResult = userService.getUserReports(userId)
// Then
// actualResult to be verified.
}