EasyMock : AssertionError expected:1, actual:0 error

[Santosh Ramachandrula]

Hello,
I am trying to test method retrieve() in Class A (I have created dummy code to represent the problem that I am facing). Please see the comments in bold below for my question.

Class A{
   
  public String retrieve(String){  
   RequestObject requestObject = new RequestObject();
   B b = new B();
   [I][B]//code fails here and gives an Assertion error as shown
   //above because I think that the object used in this call is diff
   //from what I used in the expectCall in the test class
   //HOW DO I mock an object like RequestObject that is being created with
   //in a method[/B][/I]
   b.retrieve(requestObject);  
  }
}
 
class B{
  public ResponseObject retrieve(RequestObject requestObject){
 
  }
}
 
EasyMockTest_Class_A{
 private A a;
 private B mockB;
public void setUp{
a = new A();
mockB = createMock(B.class);
}
 
 public void testRetrieve(){
expect(mockB.retrieve(new RequestObject())).andReturn(ResponseObject);
replay(bMock);
a.retrieve("ABC");
 }
 
}

[ May 21, 2008: Message edited by: Santosh Ramachandrula ]

[Lasse Koskela]

Originally posted by Santosh Ramachandrula:

Class A {
  public String retrieve(String){  
    RequestObject requestObject = new RequestObject();
    B b = new B();
    [I]//code fails here and gives an Assertion error as shown
    //above because I think that the object used in this call is diff
    //from what I used in the expectCall in the test class
    //HOW DO I mock an object like RequestObject that is being created with
    //in a method[/I]
    b.retrieve(requestObject);  
  }
}

You don't mock an object that is being created within a method. The only way to do that would be to modify the actual byte code with a library such as BCEL or ASM, replacing the byte code instructions for "B b = new B()" with something else.

A much more viable option is to expose "B" so that you can indeed swap in a test double. For example, you could do something like this:

public class A {
 
  public String retrieve(String) {
    RequestObject requestObject = new RequestObject();
    B b = createB();
    b.retrieve(requestObject);
  }
 
  protected B createB() {
    return new B();   // in production, instantiate "B"
  }
}
 
public class TestA {
 
    private A a;
    private B mockB;
 
    public void setUp() {
        mockB = EasyMock.createMock(B.class);
        a = new A() {
            protected B createB() {
                return mockB;
            }
        };
    }
 
    public void testRetrievingSomething() {
        // now we can test a [I]subclass of[/I] A that doesn't
        // use "B" but rather our very own mock object
    }
}