mocking protected method

Question

I want to mock an inherited protected method. I can't call this method directly from java code as it is inherited from class that in another package. I can't find a way to specify this method to stub in in when(...)

package a;

public class A() {
    protected int m() {}
}

package b;

public class B extends a.A {
    // this class currently does not override m method from a.A
    public asd() {}
}

// test
package b;

class BTest {
    @Test
    public void testClass() {
        B instance = PowerMockito.spy(new B());
        PowerMockito.when(instance, <specify a method m>).thenReturn(123);
        //PowerMockito.when(instance.m()).thenReturn(123); -- obviously does not work
    }
}

I looked at PowerMockito.when overrides and this seems that they are all for private methods only!

How to specify protected method?

Answer 1

Nutshell: Can't always use when to stub spies; use doReturn.

Assuming static imports of spy and doReturn (both PowerMockito):

@RunWith(PowerMockRunner.class)
@PrepareForTest(B.class)
public class BTest {
    @Test public void testClass() throws Exception {
        B b = spy(new B());
        doReturn(42).when(b, "m");
        b.asd();
    }
}

You could also @PrepareForTest(A.class) and set up the doReturn on when(a, "m"). Which makes more sense depends on the actual test.