Mock final class in java using mockito library

Question

I have one class which is final, which has one method on which I want to perform certain action. Because of this I want to create object of final class. But I am unable to create it, following is my class.

public final class A {

     private String name;

     A(String name){
       this.name = name;
     }

     public String getName(){
       return name;
     }
}

In my junit test case I want to create object of that class, like below

 Class TestA{

      @Test
      public void testA(){
          A a = mock(A.class);

          when(a.getName()).then("ABC"); //on this line i am getting exception
      }
 }

I have tried it by using new keyword also, but not working. So is there anyway to create a mock object of final class?

Following exception I facing,

org.mockito.exceptions.base.MockitoException: 
Cannot mock/spy class A
Mockito cannot mock/spy following:
  - final classes
  - anonymous classes
  - primitive types
    at com.rocket.map.resources.TestA.testA(TestA.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Why do you need to mock that class? Why dont you just use it?! — tddmonkey, May 25 '17 at 13:30
Why mock it? Why not just instantiate it with name `"ABC"` ? — khelwood, May 25 '17 at 13:30
`on this line i am getting exception` If your code throws some `Exception`, please always include the stack trace. — Turing85, May 25 '17 at 13:34
@dullpointer Incorrect. You cannot mock final classes with Mockito 1.x., you can mock final classes with Mockito 2.x. See [the FAQ from mockito](https://github.com/mockito/mockito/wiki/FAQ) for more detail. — Turing85, May 25 '17 at 13:42
@tddmonkey The class could be a placeholder for a much more complex class. Don't assume everything on stack overflow is literal. Sometimes you have to provide simple examples so others can reproduce. — Novaterata, May 25 '17 at 13:45
@tddmonkey which is most probably a [MCVE](https://stackoverflow.com/help/mcve) to demonstrate the problem. — Turing85, May 25 '17 at 13:58
can anyone please provide example by referring above example, I am struggling on it. (with/without using mockito v 2) — Tushar Deshpande, May 25 '17 at 14:13
Thanks @Turing85 correcting me . I have deleted my comment . — Bharat DEVre, May 26 '17 at 13:52

score 5 · Accepted Answer · answered May 25 '17 at 14:01

try using this.

Use the @RunWith(PowerMockRunner.class) annotation at the class-level of the test case.
Use the @PrepareForTest(ClassWithFinal.class) annotation at the class-level of the test case.
Use PowerMock.createMock(ClassWithFinal.class) to create a mock object for all methods of this class (let's call it mockObject).
Use PowerMock.replay(mockObject) to change the mock object to replay mode.
Use PowerMock.verify(mockObject) to change the mock object to verify mode.

Also refer this answer - link

And Tutorial.

Both look easy to implement.

gati sahu · Answer 2 · 2017-05-25T13:53:22.063

1

This is not possible with Mockito v1 Please look into this link. I think in advance version or powermockito you can do this.Powermockito example

edited May 25 '17 at 13:53

answered May 25 '17 at 13:45

gati sahu

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1

When recommending Powermock, you should always add the tiny bit of information that Powermock messes with the bytecode. – Turing85 May 25 '17 at 13:49

Mock final class in java using mockito library

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