How to mock private method for testing using PowerMock?

by

I don’t see a problem here. With the following code using the Mockito API, I managed to do just that :

public class CodeWithPrivateMethod {

    public void meaningfulPublicApi() {
        if (doTheGamble("Whatever", 1 << 3)) {
            throw new RuntimeException("boom");
        }
    }

    private boolean doTheGamble(String whatever, int binary) {
        Random random = new Random(System.nanoTime());
        boolean gamble = random.nextBoolean();
        return gamble;
    }
}

And here’s the JUnit 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;
import static org.mockito.Matchers.anyInt;
import static org.mockito.Matchers.anyString;
import static org.powermock.api.mockito.PowerMockito.when;
import static org.powermock.api.support.membermodification.MemberMatcher.method;

@RunWith(PowerMockRunner.class)
@PrepareForTest(CodeWithPrivateMethod.class)
public class CodeWithPrivateMethodTest {

    @Test(expected = RuntimeException.class)
    public void when_gambling_is_true_then_always_explode() throws Exception {
        CodeWithPrivateMethod spy = PowerMockito.spy(new CodeWithPrivateMethod());

        when(spy, method(CodeWithPrivateMethod.class, "doTheGamble", String.class, int.class))
                .withArguments(anyString(), anyInt())
                .thenReturn(true);

        spy.meaningfulPublicApi();
    }
}

More Related Contents:

  1. Mock a constructor with parameter
  2. Using PowerMockito.whenNew() is not getting mocked and original method is called
  3. Mockito – NullpointerException when stubbing Method
  4. Mocking Logger and LoggerFactory with PowerMock and Mockito
  5. PowerMock, mock a static method, THEN call real methods on all other statics
  6. Powermock – java.lang.IllegalStateException: Failed to transform class
  7. PowerMockito mock single static method and return object
  8. Test class with a new() call in it with Mockito
  9. Initialising mock objects – MockIto
  10. Final method mocking
  11. Before and After Suite execution hook in jUnit 4.x
  12. Testing Private method using mockito
  13. Mockito : how to verify method was called on an object created within a method?
  14. How to tell a Mockito mock object to return something different the next time it is called?
  15. How to test code dependent on environment variables using JUnit?
  16. How to mock new Date() in java using Mockito
  17. Mockito How to mock and assert a thrown exception?
  18. How to write junit tests for interfaces?
  19. junit & java : testing non-public methods [duplicate]
  20. How to verify that a specific method was not called using Mockito?
  21. JUnit: how to avoid “no runnable methods” in test utils classes
  22. junit testing for user input using Scanner
  23. Why is my class not calling my mocked methods in unit test?
  24. Calling callbacks with Mockito
  25. Why are my mocked methods not calld when executing a unit test?
  26. Forming Mockito “grammars”
  27. JUnit tests for AspectJ
  28. Java verify void method calls n times with Mockito
  29. Why are my mocked methods not called when executing a unit test?
  30. Integration tests for AspectJ

Leave a Comment