null exception for mocked service-CodePudding

I want to mock and test this Java code:

public class BusterClient {

    public BusterClient() {
    }

    @Autowired
    public BusterClient(PromoCodeService promoCodeService) {
        this.promoCodeService = promoCodeService;
    }

    private Optional<PromoCode> getPromoCode(CustomerRegistrationEvent event) {
        Optional<Long> campaignId = getCampaignIdAsLong(event);
        if (!event.hasPromoCode() || !campaignId.isPresent()) {
            return Optional.empty();
        }

        return promoCodeService.findByCampaignPromoCodeIds(campaignId.get(), event.getPromoCode());
    }
}

I created this test code:

@InjectMocks
private BusterClient app = new BusterClient();

@Test
public void testTrackedReferralNotMatchingPromoCode() throws Exception {
    
    PromoCodeService o = mock(PromoCodeService.class);
    when(o.findByCampaignPromoCodeIds(Long.valueOf(12), "test")).thenReturn(Optional.of(PromoCode.builder().id(Long.valueOf(1)).build()));

    try {

        Method method = BusterClient.class.getDeclaredMethod("getPromoCode", CustomerRegistrationEvent.class);
        method.setAccessible(true);
        method.invoke(app, customerRegistrationEvent);

    } catch (InvocationTargetException e) {
        e.getCause().printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

But I get error: promoCodeService.findByCampaignPromoCodeIds(java.lang.Long, String)" because "this.promoCodeService" is null

Do you know what is the proper way to mock PromoCodeService service?

CodePudding user response：

You must do something like this

    @Mock
    private PromoCodeService promoCodeService;
    @InjectMocks
    private BusterClient app;
    
      @BeforeEach
      void setUp() {
    
        MockitoAnnotations.initMocks(this);
      }
    
    @Test
    public void testTrackedReferralNotMatchingPromoCode() throws Exception {
        
        when(promoCodeService.findByCampaignPromoCodeIds(Long.valueOf(12), "test")).thenReturn(Optional.of(PromoCode.builder().id(Long.valueOf(1)).build()));
    
        ...
// Test a public method and not a private method. Use one public method that in turn will call your "getPromoCode".
    }

CodePudding user response：

Try to inject your mocked object into the client you are creating, and create the client in the test method instead of making it class variable

var app = new BusterClient(o); //where o is the object you created with mockito