PowerMock: stub methods from parent class

Question

I'm using PowerMock and I'd like to know how to keep all behavior of the child class, but stub super calls that may be overriden by the child.

Say I have this class:

public class A {
    public String someMethod() {
        return "I don't want to see this value";
    }
}

and a sub class:

public class B extends A {
    @Override
    public String someMethod() {
        return super.someMethod() + ", but I want to see this one";
    }
}

How do I stub the call to super.someMethod()?

I've tried

@Test
public void test() {
    B spy = PowerMockito.spy(new B());
    PowerMockito.doReturn("value").when((A)spy).someMethod();

    assertEquals("value, but I want to see this one", spi.someMethod());
}

Solution 1

You can try suppressing the methods from the Parent class,

PowerMockito.suppress(methodsDeclaredIn(A.class));

Here's an article on Stubbing, suppressing and replacing with PowerMock that might be of some use.

https://www.jayway.com/2013/03/05/beyond-mocking-with-powermock/

Solution 2

Don't forget to add @PrepareForTest({ParentClassToSupress.class}) on your test class. Then you can do as Steve suggests and suppress methods in the parent: PowerMockito.suppress(methodsDeclaredIn(ParentClassToSupress.class));

Solution 3

The cast you're attempting is not going to work as you are expecting. However, I think you have a couple of options to get around this, certainly with PowerMockito.

Take a look at this StackOverflow answer.

Comments

[Keith]

What's happening in the current test case?

[jchitel]

It's stubbing the subclass's method.

[javaPlease42]

Seems like this bug :github.com/jayway/powermock/issues/487

[jchitel]

Yea, so I was trying really hard to find a solution to this because the point of PowerMock is that you shouldn't have to change the structure of your code to make it testable. However, I realized that I need to balance that with the amount of time and effort it takes me to write the tests, so I modified the code to make it easier to test. But thanks for the resource!

[javaPlease42]

The suppress method is not helpful because I need to return a mocked value. Thank you though.

[Steve]

How about using PowerMockito.replace() to replace the parents method with one that returns your mocked value?