PowerMockito Enum in Switch Statement throwing NPE

Question

I'm testing a class with PowerMockRunner which retrieves a value ENUM from a static method in a helper class. A null pointer is thrown when this value ENUM is passed into a SWITCH statement in the classUnderTest.

I've debugged and can see the ENUM is set correctly (name, type, ordinal all as expected) so am unsure as to why the NPE is thrown. Anybody encounter similar issue?

Note: PowerMockito is required as classUnderTest includes calls to private methods. Below is complete example with a lot of code (unrelated to issue) removed. Comments added at point where ENUM is set and NPE is thrown

ClassUnderTest:

public class TestService extends BaseXAServiceBean
{

@Override
public ValueObject runExecute(ValueObject param) throws RemoteException, ServiceException
{
    try
    {
        ValueEnum value = ValueServiceHelper.getValueType(param1(),
                    param2());
        // value populated successfully with ENUM at this point         


        // NPE thrown when value is passed into below switch
        switch (value)
        {
            case VALUE1:
            {                       
                // logic here...
                break;
            }

            case VALUE2:
            {                       
                // logic here...
                break;
            }

            case VALUE3:
            {                       
                // logic here...
                break;
            }
        }
    }
    catch (ServiceException e)
    {
        throw e;
    }
    catch (Exception e)
    {
        throw new ServiceException(e, AppErrorCodes.INT.SL06, AppErrorCodes.SL06.E04);
    } finally {
        // clean up
    }
}
}

Helper Class with static method:

public class ValueServiceHelper
{
public static ValueEnum getValueType(String param1, String param2) throws ServiceException
    {
        ValueEnum retVal = ValueEnum.VALUE3;

        // proxy is mocked
        ProductProxy proxy = ProxyFactory.createFactory("1").getProductProxy();

        try
        {
            if (proxy.isValue1(param2))
            {
                retVal = ValueEnum.VALUE1;
            }
            else if (proxy.isValue2(param2))
            {
                retVal = ValueEnum.VALUE2;
            }

        }
        return retVal;
    }
}

Test Class:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ProxyFactory.class})
public class ValueTest {

@Spy
@InjectMocks
private TestService service = new TestService();

@Mock
private ProxyFactory proxyFactory;

@Mock
private Proxy proxy;

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

    PowerMockito.mockStatic(ProxyFactory.class);
}

@Test
public void testSuccess() throws Exception {
    // given

    // when
PowerMockito.when(ProxyFactory.createFactory("1")).thenReturn(proxyFactory);
PowerMockito.when(proxyFactory.getProductProxy()).thenReturn(proxy);
    PowerMockito.when(proxy.isValue1(param2)).thenReturn(true);
    PowerMockito.when(proxy.isValue2(param2)).thenReturn(true);
    service.runExecute(request);        

    // then

}
}

Answer 1

This is an issue with PowerMock that has existed since at least 2015. The only way to fix it that I'm aware of is to use if statements instead of a switch.