Powermock static final method in final class

Question

The Test case I am writing for:

public class AClassUnderTest {

    // This test class has a method call
    public Long methodUnderTest() {

         // Uses the FinalUtilityClass which contains static final method
         FinalUtilityClass.myStaticFinalMethod(<3-parameters-here>);

         // I want to mock above call so that test case for my "methodUnderTest" passes
    }
}

I have one final class.

public final class FinalUtilityClass {

   /**
    * Method has 3 parameters
    */
   public static final MyBean myStaticFinalMethod(<3-parameters-here>) {

   }
}

I have already added below code in my test class:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ FinalUtilityClass.class })

I want to write test case for mocking it. I want to mock the call of myStaticFinalMethod() so that I can get the expected MyBean instatnce which I can use in further code to pass my test case.

The <3-parameters-here> are Calendar, String, String.

I tried doing:

1)

PowerMockito.mock(FinalUtilityClass.class)
PowerMockito.when(FinalUtilityClass.myStaticFinalMethod(<3-parameters-here>).thenReturn(new MyBean());

2)

PowerMockito.mockStatic(FinalUtilityClass.class)
PowerMockito.when(FinalUtilityClass.myStaticFinalMethod(<3-parameters-here>).thenReturn(new MyBean());

3)

PowerMockito.spy(FinalUtilityClass.class)
PowerMockito.when(FinalUtilityClass.myStaticFinalMethod(<3-parameters-here>).thenReturn(new MyBean());

But nothing worked for me. Please suggest what is correct way for mocking static final method in final class.

Did you add `@RunWith(PowerMockRunner.class)` as a class level annotation in the test class? — gmanjon, Jul 11 '17 at 12:24
Ok, sorry, Prepaturely answered then, I'll delete my answer. Thanks and sorry. — gmanjon, Jul 11 '17 at 12:41
Possible duplicate of [TestNG + Mockito + PowerMock - verifyStatic() does not work](https://stackoverflow.com/questions/35801550/testng-mockito-powermock-verifystatic-does-not-work) — talex, Jul 11 '17 at 12:44
Possible duplicate of https://stackoverflow.com/questions/10583202/powermockito-mock-single-static-method-and-return-object — talex, Jul 11 '17 at 12:45

GhostCat · Answer 1 · 2017-07-12T07:41:35.323

9

The following steps are required to mock calls to static methods:

Use the @RunWith(PowerMockRunner.class) annotation at the class-level of the test case.
Use the @PrepareForTest(ClassThatContainsStaticMethod.class) annotation at the class-level of the test case
Use PowerMock.mockStatic(ClassThatContainsStaticMethod.class) to mock all methods of this class

When you follow these steps as documented, your tests should work. And as the OP seems to be confused about PowerMock vs. PowerMockito - that is (more or less) the same thing:

PowerMock and PowerMockito are based on the same technology. They just have different "connectors" to either work with EasyMock or Mockito. So, yes the above example says PowerMock.mockStatic() - but PowerMockito has mockStatic() methods as well. In that sense: the core things (for example regarding preparation with annotations) are the same. See here for example (they are so close that the linked tutorial says "Intro to PowerMock" - although it does introduce PowerMockito.

And as you seem to not believe me - see this example:

package ghostcat.test;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

final class ClassWithStatic {
    public final static int ignoreMethodCall(String a, String b, int c) {
        System.out.println("SHOULD NOT SHOW UP: " + a);
        return c;
    }
}

@RunWith(PowerMockRunner.class)
@PrepareForTest(ClassWithStatic.class)
public class MockStaticTest {
    @Test
    public void test() {
        PowerMockito.mockStatic(ClassWithStatic.class);
        PowerMockito.when(ClassWithStatic.ignoreMethodCall("a", "b", 5)).thenReturn(42);
        org.junit.Assert.assertEquals(ClassWithStatic.ignoreMethodCall("a", "b", 5), 42);
    }
}

This test passes; and doesn't print anything. Therefore the final static method gets mocked.

edited Jul 12 '17 at 07:41

answered Jul 11 '17 at 12:25

GhostCat

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2

for static method it works well, but how about static final ? – Mandar Pandit Jul 11 '17 at 12:27
According to the documentation: > Note that you can mock static methods in a class even though the class is final. The method can also be final – gmanjon Jul 11 '17 at 12:31
As per point **2)**, I tried with `mockStatic` but it dosen't mock the final method. It goes inside the method, which I want to mock. This works well with `static` methods, which are not final. – Mandar Pandit Jul 11 '17 at 12:35
This answer uses `PowerMock` and the one which is used in the question is `PowerMockito`. – Mandar Pandit Jul 12 '17 at 05:12
I agree with your example, what if in case `ClassWithStatic` is final ? My issue lies at that point in case of final class. – Mandar Pandit Jul 12 '17 at 07:35
Wondering how much more time I have to spent here ... well, my own fault. I just updated the example and made the class final, too. And it still works. You see: all of that **does not** matter. Because what PowerMock(ito) is doing: it **changes** the byte code of the classes marked with @PrepareForTest . In other words: the **production** source code doesn't matter - because PowerMock will do its dark magic and simply create **different** byte code for that class at runtime. And seriously: have you tried taking my example (it is **complete**, just copy) and work with that? – GhostCat Jul 12 '17 at 07:44
sure, will try this example in my class. – Mandar Pandit Jul 12 '17 at 08:31
1

It only works with Junit 4 but not Junit 5. – Mingtao Sun Jul 16 '21 at 04:42

Allan Nobre · Answer 2 · 2021-06-17T05:33:36.650

I faced a similar problem, and it cost me a lot of time.

I solved it, based on this Mock system class with PowerMock documentation, when I realized that the @PrepareForTest({ SomeClassToBePreparedForTesting.class }) must receive the class that calls the static methods defined in the final class, so the preparation for the test, in your case, must receive the AClassUnderTest.class.

@RunWith(PowerMockRunner.class)
@PrepareForTest({ AClassUnderTest.class })

The correct way to mock the final class with the target static method is to use the PowerMock.mockStatic(FinalClassThatDefinesStaticMethod.class), in your case the FinalUtilityClass.class.

PowerMockito.mockStatic(FinalUtilityClass.class)
PowerMockito.when(FinalUtilityClass.method(params)).thenReturn(return);

In addition, if you have some issue like: 'It's not possible to mock final methods', you can create the file org/powermock/extensions/configuration.properties and set this config mockito.mock-maker-class=mock-maker-inline like the PowerMockito documentation presents.

Powermock static final method in final class

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