Mockito Spy Test

Question

I am using Mockito to write tests for code. However I am stuck at following scenario - Class A has 2 methods, method1() and method2(). I tried using ArgumentCaptor to catch values sent to method2(). But, since I am using @Spy, I cannot use Matchers.

How do I test method1()?

class A{
    B b;
    method1(arg1, arg2){
       //some logic
       method2(arg1, arg2, ....argN);
    }

   method2(arg1, arg2,....argN){
       //some logic
       b.method3(arg1, arg2...);
   }
}

How to verify method2 receives same argument values? Following is the test class I wrote:

Class TestA{

@Mock
B b;

@Spy
@InjectMocks   //required else b is null
A a = new A();

@Test
public void testMethod1(){

 a.method1(arg1, arg2);

  //How to verify method2 receives same argument values (arg1, arg2)????
  //verify(a, times(1)).method2(.......);   
}

}

Answer 1

I was intrigued by this post and the comments left by @David so I decided to code a working example for those who follow like me

/*
 * class to test
 */
public class A {

    public void methodA(String str) {
        this.methodB(str);
    }

    protected void methodB(String str) {
        // some implementation
    }
}

We want to assert that the value being passed into methodB() is what we expect. Reading up on the ArgumentCaptor led me to discover the equivalent Captor Annotation

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.verify;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.ArgumentCaptor;
import org.mockito.Captor;
import org.mockito.Spy;
import org.mockito.runners.MockitoJUnitRunner;

@RunWith(MockitoJUnitRunner.class)
public class MultipleMethodCallTest {

    @Spy
    A a = new A();

    @Captor ArgumentCaptor<String> captor;

    @Test
    public void captureSecondMethodCallArgument() throws Exception {

        // EXPECTED

        String greeting = "hello world";

        // PERFORM TEST

        a.methodA(greeting);

        // ASSERT

        verify(a).methodB(captor.capture());

        assertEquals(greeting, captor.getValue());
    }
}

This example was tested with

• mockito-all-1.8.5.jar
• junit-4.8.2.jar

Answer 2

You cant, you have to verify it by B's method3 call. If your args to method2 have no effect on method3, theses args could be useless at all?!

Answer 3

You can use matchers with spies; this works just fine. I don't know why you thought that you couldn't.

I took your source code and edited it to make it compile. I then added a call to MockitoAnnotations.initMocks - you need this to create the spy and the mock, and to inject the mock (unless you use the MockitoJUnitRunner , which does the initMocks for you). I put the verify of the call to method2 back in. This worked fine.

So, contrary to Omnaest's answer, you don't need to use B's method3 to verify this. I suspect that your only problem was that you had forgotten the initMocks .

Good luck with this, and feel free to post again if you need any more help.