Mock a void method which change the input value

Question

Hi,

How could I mock a void method with parameters and change the value parameters?

I want to test a class (SomeClassA) which has a dependency on another class (SomeClassB). I would like to mock SomeClassB.

public class SomeClassA
{
   private SomeClassB objectB;    
   private bool GetValue(int x, object y)
   {
      objectB.GetValue(x, y);      // This function takes x and change the value of y
   }
}

SomeClassB implements interface IFoo

public interface IFoo 
{
   public void GetValue(int x, SomeObject y)     // This function takes x and change the value of y
}

pulic class SomeClassB : IFoo
{
   // Table of SomeObjects 
   public void GetValue(int x, SomeObject y)
   {
       // Do some check on x
       // If above is true get y from the table of SomeObjects
   }
}

Then in my unit test class, I prepared a delegate class which mimic SomeClassB.GetValue:

private delegate void GetValueDelegate(int x, SomeObject y);
private void GetValue(int x, SomeObject y)
{  // process x
   // prepare a new SomeObject obj
   SomeObject obj = new SomeObject();
   obj.field = x;
   y = obj;
}

In the mock part I wrote:

IFoo myFooObject = mocks.DynamicMock();
Expect.Call(delegate { myFooObject.Getvalue(5, null); }).Do(new GetValueDelegate(GetValue)).IgnoreArguments().Repeat.Any();

SomeObject o = new SomeObject();

myFooObject.getValue(5, o);
Assert.AreEqual(5, o.field);   // This assert fails!

I checked a couple of posts and delegate seems to be the key to mock a void method. However, after trying the above, it's not working. Could you advise if there is anything wrong in my delegate class? Or something wrong in the mock statement?

---

My RhinoMocks is 3.5 and seems like it's dropping the Do part if I include IgnoreArguments() I just found this page: http://www.mail-archive.com/[email protected]/msg00287.html

Now I have changed

Expect.Call(delegate { myFooObject.Getvalue(5, null); }).Do(new GetValueDelegate(GetValue)).IgnoreArguments().Repeat.Any();

to

Expect.Call(delegate { myFooObject.Getvalue(5, null); }).IgnoreArguments().Do(new GetValueDelegate(GetValue)).Repeat.Any();

And now it works perfectly fine!

Answer 1

Kar, are you using a really old version .NET or something? This syntax has been outdated for quite some time. I also think that you're doing it wrong. Rhino Mocks isn't magic - it doesn't do anything you couldn't do yourself using a couple extra lines of code.

For example if I have

public interface IMakeOrders {
  bool PlaceOrderFor(Customer c);
}

I can implement it with:

public class TestOrderMaker : IMakeOrders {
  public bool PlaceOrderFor(Customer c) {
    c.NumberOfOrders = c.NumberOfOrder + 1;
    return true;
  }
}

or

var orders = MockRepository.GenerateStub<IMakeOrders>();
orders.Stub(x=>x.PlaceOrderFor(Arg<Customer>.Is.Anything)).Do(new Func<Customer, bool> c=> {
    c.NumberOfOrders = c.NumberOfOrder + 1;
    return true;  
});

Read this intro to RM that I wrote up for some contractors.