Powermockito and overriding hashcode

[Horace Le Cheval]

Hi guys,

(maybe?) stupid question :

i'm babystepping with powermock (1.5.6), 

in order to test (mockito (1.9.5) / Junit (4.10) ) some legacy code dealing with hashcode.

I keep bumping on the mock of a class overriding the hashcode method, which raises an exception(*) 

and i did not manage to find an answer on the webs.

(*) exception being

org.mockito.exceptions.misusing.MissingMethodInvocationException: 

when() requires an argument which has to be 'a method call on a mock'.

For example:

    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:

1. you stub either of: final/private/equals()/hashCode() methods.

   Those methods *cannot* be stubbed/verified.

2. inside when() you don't call method on mock but on some other object.

3. the parent of the mocked class is not public.

   It is a limitation of the mock engine.

Not sure, but might be related to the post "18 Dec 2013: Cannot mock equals and hashCode in own class, while it works with InitialContext"

Basically here is a reproduction of my issue (SubHashMap is just an example, case occurs with standalone class):

import org.junit.Test;

import org.junit.runner.RunWith;

import org.powermock.core.classloader.annotations.PrepareForTest;

import org.powermock.modules.junit4.PowerMockRunner;

import java.util.HashMap;

import static org.junit.Assert.assertTrue;

import static org.powermock.api.mockito.PowerMockito.mock;

import static org.powermock.api.mockito.PowerMockito.when;

@RunWith(PowerMockRunner.class)

@PrepareForTest({HashCodeTest.SubHashMap.class})

public class HashCodeTest {

@Test

public void  getHashmap() {

HashMap actor = mock(HashMap.class);

when(actor.hashCode()).thenReturn(123456);

assertTrue("yay i'm good", true);

}

@Test

public void  getsubHashmap() {

try {

SubHashMap actor = mock(SubHashMap.class);

when(actor.hashCode()).thenReturn(123456);

} catch (Exception e) {

assertTrue("boo i'm bad",false);

e.printStackTrace();

}

}

public class SubHashMap extends HashMap{

@Override

public int hashCode() {

return super.hashCode();

}

@Override

public boolean equals(Object o) {

return super.equals(o);

}

}

}

Does someone, by any chance, have a suggestion ? 

Thanks and Cheers

[Johan Haleby]

Looks like a bug to me. A work-around would be to stub it instead:

stub(method(SubHashMap.class, "hashCode")).toReturn(123456);

SubHashMap actor = new SubHashMap();

int hashCode = actor.hashCode();

where "stub" is statically imported from org.powermock.api.support.membermodification.MemberModifier.stub and "method" from org.powermock.api.support.membermodification.MemberMatcher.method.

/Johan

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[Horace Le Cheval]

Ok,

thanks a lot for your swift feedback,

Using the real object would trigger its hashcode/equals implementation, hence would not require to stub it.

As you suggest, i will probably rewire my factory to return objects instead of mocks for these cases.

Thanks again and have a nice day.

H