How to mock private final members

Question

//member of some class example "myclass"
private final IBinder mICallBack = new Binder();

Now my problem is that when I am creating myclass object it is calling native methods of android.os.Binder.

What I want is mock IBinder.class and suppress new object creation with my mock object.

How to mock this?

Possible duplicate of [How to mock final field? mockito/powermock](http://stackoverflow.com/questions/23629766/how-to-mock-final-field-mockito-powermock) — SpaceTrucker, Mar 14 '17 at 12:06

score 1 · Answer 1 · answered Mar 17 '17 at 05:14

There is an example in EasyMock for mocking native methods. Hope it helps. The source code could be found here in github repository.

package samples.nativemocking;

/**
 * The purpose of this class is to demonstrate that it's possible to mock native
 * methods using plain EasyMock class extensions.
 */
public class NativeService {

    public native String invokeNative(String nativeParameter);

}


package samples.nativemocking;

/**
 * The purpose of this class is to invoke a native method in a collaborator.
 */
public class NativeMockingSample {

    private final NativeService nativeService;

    public NativeMockingSample(NativeService nativeService) {
        this.nativeService = nativeService;
    }

    public String invokeNativeMethod(String param) {
        return nativeService.invokeNative(param);
    }
}

package samples.junit4.nativemocking;

import org.junit.Test;
import samples.nativemocking.NativeMockingSample;
import samples.nativemocking.NativeService;

import static org.easymock.EasyMock.*;
import static org.junit.Assert.assertEquals;

/**
 * This test demonstrates that it's possible to mock native methods using plain
 * EasyMock class extensions.
 */
public class NativeMockingSampleTest {

    @Test
    public void testMockNative() throws Exception {
        NativeService nativeServiceMock = createMock(NativeService.class);
        NativeMockingSample tested = new NativeMockingSample(nativeServiceMock);

        final String expectedParameter = "question";
        final String expectedReturnValue = "answer";
        expect(nativeServiceMock.invokeNative(expectedParameter)).andReturn(expectedReturnValue);

        replay(nativeServiceMock);

        assertEquals(expectedReturnValue, tested.invokeNativeMethod(expectedParameter));

        verify(nativeServiceMock);
    }
}

score 0 · Answer 2 · answered Mar 13 '17 at 11:19

0

This should do the trick:

@RunWith(PowerMockRunner.class)
@PrepareForTest(Binder.class)
public class ClassTest {
  @Mock
  private Binder binderMock;

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

  @Test
  public void doSomething() throws Exception {
      // Arrange    
      PowerMockito.whenNew(Binder.class).withNoArguments()
         .thenReturn(binderMock);

      //.. rest of set-up and invocation
  }

}

answered Mar 13 '17 at 11:19

Maciej Kowalski

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it is not working it is showing UnsuportedOperationException : init is native – Ameer ali khan Mar 13 '17 at 11:42
so the real constructor is invoked? – Maciej Kowalski Mar 13 '17 at 11:53
no it is showing exception in line where i am constructing object of my class under test – Ameer ali khan Mar 13 '17 at 12:02
i think mocking a final variable that is initialized using new will not be possible using PowerMockito.whenNew() – Ameer ali khan Mar 13 '17 at 14:38

How to mock private final members

2 Answers2