使用 PowerMockito 时出现 NullPointerException

Question

getting null pointer exception while mocking getTimeZone method. defaultSystemTimezone is populated from property file.

SummaryServiceTest.java: 

@RunWith(PowerMockRunner.class)
@PrepareForTest({Calendar.class, TimeZone.class})
@ExtendWith(SpringExtension.class)
class SummaryServiceTest{

    @Mock
    BookingRepository bookingRepository;
    
    @InjectMocks
    private SummaryService summaryService;

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

    @Test
    public void getBookingRejections() throws Exception {
        TimeZone timezoneObj = TimeZone.getTimeZone("America/Cambridge_Bay");
        PowerMockito.mockStatic(TimeZone.class);
        Mockito.when(TimeZone.getTimeZone(eq("America/Cambridge_Bay"))).thenReturn(timezoneObj);
        Calendar calendar1 = Calendar.getInstance(TimeZone.getDefault(), Locale.US);
        Calendar ac = PowerMockito.mock(Calendar.class);
        PowerMockito.doReturn(calendar1).when(ac , "getInstance");
        Boolean bookingRejectionsByWeekForCarrierList = summaryService.getBookingRejections();
    }
}

SummaryService.java:

@Service
public class SummaryService {

    @Autowired
    private BookingRepository bookingRepository;
    
    @Value("${timezone.default}")
    private String defaultSystemTimezone;
    
    public Boolean getBookingRejections() {
            Calendar calendarFirstDayOfWeek = Calendar.getInstance(TimeZone.getTimeZone(defaultSystemTimezone), Locale.US);
            return true;
        }
    }
    
application.properties:

    timezone.default=America/Cambridge_Bay
    

getting below exception:

java.lang.NullPointerException
    at java.util.TimeZone.parseCustomTimeZone(TimeZone.java:783)
    at java.util.TimeZone.getTimeZone(TimeZone.java:562)
    at java.util.TimeZone.getTimeZone(TimeZone.java:516)
    at com.booking.service.SummaryServiceTest.getBookingRejections(SummayServiceTest.java:)
    

not able to exact problem even TimeZone is mocked. here trying to get calendar object.

Answer 1

resolved the problem by adding setter for defaultSystemTimezone variable of SummaryService. and set the value of var in test method.

SummaryService.java:

@Service
public class SummaryService {

    @Autowired
    private BookingRepository bookingRepository;
    
    @Setter
    @Value("${timezone.default}")
    private String defaultSystemTimezone;
    
    public Boolean getBookingRejections() {
            Calendar calendarFirstDayOfWeek = Calendar.getInstance(TimeZone.getTimeZone(defaultSystemTimezone), Locale.US);
            return true;
        }
    }

    @Test
        public void getBookingRejections() throws Exception {
            summaryService.setDefaultSystemTimezone("America/Cambridge_Bay");
            //execute test
        }