Question

I have a service layer method that recieves an object(Dto) as a parameter.

Within that method I new up a business object and i pass the values of the properties of the Dto to the properties of the business object. I then pass the business object as a parameter to a repository method call.

How will my unit test ensure that the business object declared in the service method under test receives the right value into its properties?

Answer 1

You can mock the repository (I hope that you can inject it into the service layer) and check whether the business object passed into the repository has the expected property values.

EDIT: An example

---

Infrastructure:

public interface IRepository
{
   void Add(BusinessObject item);
}

public sealed class ServiceLayerContext
{
   private readonly IRepository repository;

   public ServiceLayerContext(IRepository repository)
   {
       this.repository = repository;
   }

   public void ProcessDto(IDtoObject dto)
   {
       var businessObject = this.CreateBusinessObject(dto);
       this.repository.Add(businessObject);
   }

   private BusinessObject CreateBusinessObject(IDtoObject dto)
   {
   }
}

Test pseudocode (because RhinoMockі not the Moq):

   [Test]
   public void ShouldCreateBusinessOBjectWithPropertiesInitializedByDtoValues()
   {
      // ARRANGE
      // - create mock of the IRepository
      // - create dto
      // - setup expectations for the IRepository.Add() method
      //   to check whether all property values are the same like in dto   
      var repositoryMock = MockRepository.GenerateMock<IRepository>();
      var dto = new Dto() { ... };
      BusinessObject actualBusinessObject = null;
      repositoryMock.Expect(x => x.Add(null)).IgnoreArguments().WhenCalled(
        (mi) => 
        {
            actualBusinessObject = mi[0] as BusinessObject;            
        }).Repeat().Any();

      // ACT
      // - create service layer, pass in repository mock
      // - execute svc.ProcessDto(dto)     
      var serviceLayerContext = new ServiceLayerContext(repositoryMock);
      serviceLayerContext.ProcessDto(dto);

      // ASSERT
      // - check whether expectations are passed
      Assert.IsNotNull(actualBusinessObject);
      Assert.AreEqual(dto.Id, actualBusinessObject.Id);
      ...
   }