[FIXED] How to fix Null Pointer Exception in Junit test?

Issue

I'm getting a Null Pointer Exception as shown in the code when I run the following Junit test. Can someone please help me fix it?

import com.apexsct.pouservice.amq.inboxlistener.GetUpdateAvailablePositionInfo;
import com.apexsct.servcomm.amq.pouservice.dto.DeliveryPositionData;

public class GetUpdateAvailablePositionInfoActionTest {
    @Mock
    protected PositionRepository positionRepo;

    @Mock
    protected UserInterfaceGroupRepository uiGroupRepo;

    @InjectMocks
    private GetUpdateAvailablePositionInfo service;

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

    @Test
    public void testEmptyRequest() {
        DeliveryPositionData response = (DeliveryPositionData) service.perform(); // NULL POINTER EXCEPTION HERE
        assertEquals(ErrorMessageConstant.INVALID_REQUEST, response.getErrMsg());
    }

}

Solution

Based on your test name you want to test a case where the request is empty. However you still need to supply an actual object, as your code does not handle the case where request is null.

You could adjust the test to look like this:

public class GetUpdateAvailablePositionInfoActionTest {

    @Mock
    protected PositionRepository positionRepo;

    @Mock
    protected UserInterfaceGroupRepository uiGroupRepo;

    @Mock // creates and injects a mock for the request
    UpdAvlbPosRequest request;

    @InjectMocks
    private GetUpdateAvailablePositionInfo service;

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

    @Test
    public void testEmptyRequest() {

        // defines that the sn of the request is an empty string
        // (Depending on what StringUtils class you use, it might also handle null correctly. 
        //  In this case this line can be removed)
        Mockito.when(request.getSn()).thenReturn("");

        DeliveryPositionData response = (DeliveryPositionData) service.perform();
        assertEquals(ErrorMessageConstant.INVALID_REQUEST, response.getErrMsg());
    }
}

Answered By - second