Question

Is it possible in Rhino.Mocks to verify whether a specified constructor was called?

Consider the following code:

public interface IFoo
{
  void Bar();
}

public class FooFactory
{

  public IFoo CreateInstance(int x, int y)
  {
    return new Foo(x, y);
  }

}

public class Foo : IFoo
{

  public Foo(int x, int y)
  {
    // ... blah
  }

  public void Bar()
  {
    // blah...
  }

}

[TestFixture]
public class FooFactoryTest
{

  [Test]
  public void Assert_Foo_Ctor_Called_By_Factory_CreateInstance()
  {

    MockRepository mocks = new MockRepository();

    using (mocks.Record())
    {
      Expect.Call( /* ???? */ );
    }

    using(mocks.Playback())
    {
      new FooFactory().CreateInstance(1, 2);
    }

    mocks.VerifyAll();

  }

}

I would like to verify that Foo(int, int) was called by the FooFactory.

Answer 1

Short answer: No, that’s not how Rhino Mocks (or any mocking framework I think) works.

Longer answer: You’re not really doing this correctly. One of several reasons to use a factory is so that you can mock out when new objects are created – this means that you would be mocking your FooFactory and providing the mock for tests of other objects. Perhaps you have a lot of logic in your factory that you would like to get under test also – consider separating that logic into another class like a builder which can be tested in isolation.