Mocking static private final variable using Powermock?

Question

I have a utility class which is a final class. There i have used injection for injecting LOGGER.

public final class Utilities {

    @Inject
    private static Logger.ALogger LOGGER;

    private Utilities() {
       //this is the default constructor. so there is no implementation
    }

    public static String convertToURl(string input){
       try{
             //do some job
          }catch(IllegalArgumentException ex){
             LOGGER.error("Invalid Format", ex);
          }
   }

}

While I writing unit testing for this method i have to mock LOGGER otherwise it will throw null pointer exception. How can i mock this LOGGER without creating instance of this class. I tried to whitebox the variable. But it only works with instances?

Does [the injection to static field](http://stackoverflow.com/questions/19225179/is-it-possible-to-inject-a-cdi-bean-into-a-static-variable-in-java-ee-6) work for you? — fracz, Apr 02 '16 at 05:47
by default guice doesn't allow static injection by design. But we can request [this](http://stackoverflow.com/questions/28513147/guice-injection-in-static-variable) — Bruce, Apr 02 '16 at 05:56
I didn't know that. I haven't used that either, but if it's able to inject static field, maybe use it to inject a mock of logger in unit test? — fracz, Apr 02 '16 at 06:05
Well, the easiest workaround is to make the variable package-private and put tests in the same package, but there's gotta be a better way. — Sergei Tachenov, Apr 02 '16 at 06:55

Artur Zagretdinov · Accepted Answer · 2018-02-12T07:10:23.307

11

This code works fine. To set static field you need to pass a class to org.powermock.reflect.Whitebox.setInternalState. Please, ensure that you use PowerMock's class from the package org.powermock.reflect because Mockito has the class with the same name.

 @RunWith(PowerMockRunner.class)
 public class UtilitiesTest {

    @Mock
    private Logger.ALogger aLogger;

    @Before
    public void setUp() throws Exception {

        MockitoAnnotations.initMocks(this); // for case them used another runner
        Whitebox.setInternalState(CcpProcessorUtilities.class, "LOGGER", aLogger);
    }

    @Test
    public void testLogger() throws Exception {
        Utilities.convertToURl("");
        verify(aLogger).error(eq("Invalid Format"), any(IllegalArgumentException.class));
    }
}

edited Feb 12 '18 at 07:10

answered Apr 02 '16 at 11:49

Artur Zagretdinov

2,034
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22

It needs updating. Whitebox is no longer used. – user447607 Feb 08 '18 at 17:59
@user447607 what did you mean by “no longer used”? The class is still exist in PowerMock and will be kept. I do not have plans to remove it. May be you meant that there is another way to do it! – Artur Zagretdinov Feb 08 '18 at 18:03
Sorry, I'll clarify. The class still exists but it's considered part of the internal API and it's use is not recommended. – user447607 Feb 08 '18 at 18:05
@user447607 I think you mixed `Whitebox` from Mockito and `Whitebox` from PowerMock. In PowerMock this class is public. Internal API is `WhiteboxImpl`. – Artur Zagretdinov Feb 08 '18 at 18:07
Sure enough. I would have named it something else just on principle. OK, I'll fix my vote when the system unlocks it. – user447607 Feb 08 '18 at 18:17
Change something innocuous in the answer and I can fix. – user447607 Feb 08 '18 at 18:21
@user447607 I’ll update my answer and specify that PowerMock’s version should be used – Artur Zagretdinov Feb 08 '18 at 18:23
which package is `@Mock` from ? I have suggestions from Powermock(deprecated) and mockito – Arun Gowda Oct 15 '19 at 06:19

Mocking static private final variable using Powermock?

1 Answers1