Calling mock method instead of real method with Mockito

Question

I have a method which needs to be called instead of the real method. Instead I get an exception. Can somebody please help me with right way to call the alternate method through mockito ?

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Invalid use of argument matchers!
2 matchers expected, 4 recorded.
This exception may occur if matchers are combined with raw values:
    //incorrect:
    someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
    //correct:
    someMethod(anyObject(), eq("String by matcher"));




    //Code starts here
class A{
   public realMethod(String s, Foo f){

   }
}

class B {
    public mockMethod(String s, Foo f) {

    }
}

class UnitTestClass{
    ClassA mock = new ClassA();
    mock.when(realMethod(any(String.class), any(Foo.class))).thenReturn(mockMethod(any(String.class),any(Foo.class));
}

you can also use thenAnswer to forward arguments and set the return dynamically. Look at the answers to this [entry](https://stackoverflow.com/questions/47534082/how-to-pass-argument-to-return-method-in-mockito). — Helia Jamshidi, Apr 06 '21 at 14:26

score 1 · Accepted Answer · answered Jun 26 '17 at 07:33

You are getting mocking wrong.

Here:

thenReturn(mockMethod(any(String.class),any(Foo.class));

That simply doesn't make sense.

Mocking works like this:

you create a mock object of some class, like A mock = mock(A.class)
you specify interactions on that mock object

Your code implies that you think that these specifications are working like "normal" code - but they do not!

What you want to do: when some object is called with certain parameters, then return the result of another method call.

Like in:

when(a.foo(x, y)).thenReturn(b.bar(x, y))

That is what want you intend to do. But thing is: it isn't that easy. You can't use the any() matcher in thee thenReturn part in order to "provide" the arguments that were passed in the when() call before! It is that simply.

Mocking should be within a specific unit test to get a specific result.

Meaning: you are not writing an ordinary program where it would make any sense to "forward" parameters to another call. In other words; your code should more look like:

when(mock.realMethod("a", someSpecificFoo)).thenReturn(mockMethod("a", someSpecificFoo))

That is the only thing possible here.

Beyond that, you might want to look into a Mockito enter link description here instead.

Long story short: it simply looks like you don't understand how to use mocking frameworks. I suggest that you step back and read/work various tutorials. This is not something you learn by trial and error.

Thanks a lot.. Appreciate your feedback.. I agree I don't understand and this is first time I'm putting my hands into this. — Sharat Chandra, Jun 26 '17 at 16:30
That's fine. You got it "good enough" to give a reasonable answer. In case you consider upvoting/accepting feel free to do that tomorrow, as I already hit the daily cap today. — GhostCat, Jun 26 '17 at 18:14

Calling mock method instead of real method with Mockito

1 Answers1