in my class i have i class-field, which i’am verfing, that the method of this class-field is invoked three times. Now i moved the logic to “CompletableFuture.sypplyAsync” approach and it does not work anymore:
My Test fails, and it says, that it will be not invoked, what i’am expecting.

My Class:

public class StartProcessService {
    private final RuntimeService runtimeService;
   
    public void handleInExkassodatenRequest(MyRequest request) {
        request.getDaten().forEach(entity -> {
            CompletableFuture.supplyAsync(() -> selectRequiredProcess(entity))
                    .thenAccept(caseId -> {
                        log.info("Case started ");
                    })
                    .exceptionally(err -> {
                        return null;
                    });
        });
    }

    private CompletableFuture<String> selectRequiredProcess(InExkassodaten entity) {
        startNewProcess(entity);
        return CompletableFuture.completedFuture(entity.getCaseId());
    }

    private void startNewProcess(InExkassodaten inExkassodaten) {
        ProcessInstance processInstance = runtimeService
                .createProcessInstanceByKey("MY_KEY")
                .execute();
    }
}

and my old test-method looks like this:

@ExtendWith(MockitoExtension.class)
@MockitoSettings(strictness = Strictness.LENIENT)
class MyServiceTest {

    @InjectMocks
    private StartProcessService startProcessService;

    @Mock(answer = Answers.RETURNS_DEEP_STUBS)
    private RuntimeService runtimeService;


    @Test
    void startProcesses() {
        startProcessService.handleInExkassodatenRequest(InExkassodatenFactory.createValidTestData());
        verify(runtimeService, times(3)).createProcessInstanceByKey(anyString());
    }
}

previously checked whether runtimeService.createProcessInstanceByKey was called.
But with introduction of CompletableFutur.supplyAsync in fails with:

Wanted but not invoked: runtimeService.createProcessInstanceByKey(
);
-> at StartProcessServiceTest.startProcesses(StartProcessServiceTest.java:52)
Actually, there were zero interactions with this mock.

How do i need to redesign code my production or testcode to test it with CompleableFuture?