Configure AutoMapper to return Mock in test layer - tdd

Question

In my app, all domain classes follow the standardization:
All implement the interface IEntity
Id properties are protected*
The properties of type IList are protected and initialized in the constructor.
Below is a classic example of a domain entity:
public class CheckListItemTemplate : IEntity
{
public virtual int Id { get; protected set; }
public virtual string Text { get; set; }
public virtual CheckListItemTemplate Parent { get; set; }
public virtual IList<CheckListItemTemplate> Itens { get; protected set; }
public CheckListItemTemplate()
{
Itens = new List<CheckListItemTemplate>();
}
public void AddItem(CheckListItemTemplate item)
{
item.Parent = this;
Itens.Add(item);
}
}
*This is because the id is generated by the database and not run the risk of some developer trying to set this property.
Test project
We have a fake generic repository used in the tests:
public class Repository<T> : IRepository<T>
where T : class, IEntity
{
private readonly IDictionary<int, T> _context = new Dictionary<int, T>();
public void Delete(T obj)
{
_context.Remove(obj.Id);
}
public void Store(T obj)
{
if (obj.Id > 0)
_context[obj.Id] = obj;
else
{
var generateId = _context.Values.Any() ? _context.Values.Max(p => p.Id) + 1 : 1;
var stub = Mock.Get<T>(obj);
stub.Setup(s => s.Id).Returns(generateId);
_context.Add(generateId, stub.Object);
}
}
// ..
}
As you can see in the Store*, all test objects (of type IEntity) should be a Mock**. This is because in UI project, when we save an object NHibernate updating the property Id. In testing project we have to do this manually, and we have no way to set the property Id with a new value, so the solution was mock the entire object to the Get property Id correspond to the new Id . Exactly what does this line stub.Setup(s => s.Id).Returns(generateId).
*By convention, objects with Id <= 0 are new and Id> 0 are existing objects in the database.
**For Mock I use Moq.
Id as protected
The biggest problem occurs because of Id property and the fact that is protected.
When we talk about the designer, is a great approach but this brings huge inconvenience when we test our application.
For example, in a test that I'm writing I need my Fake repository with some data already populated.
Code
Follow me. I have the following classes (+ CheckListItemTemplate shown above.)
public class Passo : IEntity
{
public int Id { get; protected set; }
public virtual IList<CheckListItemTemplate> CheckListItens { get; protected set; }
}
public class Processo : IEntity
{
public virtual int Id { get; protected set; }
public virtual Passo Passo { get; set; }
public virtual IList<CheckListItem> CheckListItens { get; protected set; }
}
After saving the Processo, the first Passo is associated with the Processo: (sorted by Ordem field following field CreateAt)
model.Passo = PassoRepositorio.All().OrderBy(p => p.Ordem).ThenBy(p => p.CreateAt).First();
model.CheckListItens.Clear();
Parallel.ForEach(Mapper.Map<IList<CheckListItem>>(model.Passo.CheckListItens), (it) => model.AddCheckListItem(it));
This code is running whenever you save a new Processo. For any test that creates a new Processo, this code will be executed!
Test
If we have to create a test that creates a new Processo, our first goal is to populate the PassoRepositorio repository with some dummy data*, with Passos and CheckListItemTemplates specifically for the above code does not fail**.
*To populate objects with dummy data I use AutoFixture.
** Will fail if no Passo is found in the repository .First() and this Passo has no checklist Mapper.Map(model.Passo.CheckListItens).
So we need a repository of Passos and each Passo with a list of CheckListItens.
Remember that every object IEntity should be an Mock<> so we can mock property Id
First attempt
First configure my TestInitialize to populate my repository with some dummy data:
var fix = new Fixture();
var listPassos = fix.Build<Mock<Passo>>()
.Do((passo) => {
passo.SetupProperty(x => x.Nome, fix.Create<string>());
passo.SetupGet(x => x.CheckListItens).Returns(
fix.Build<CheckListItemTemplate>() // Needs to a Mock<>
.With(p => p.Texto)
.OmitAutoProperties()
.CreateMany(5).ToList()
);
})
.OmitAutoProperties()
.CreateMany(10);
foreach (var item in listPassos)
passoRepository.Store(item.Object);
Then I can run the tests:
[TestMethod]
public void Salvar_novo_processo_modificar_data_atendimento_passo_atual()
{
// Arrange
var fix = new Fixture();
var vm = fix.Create<ProcessoViewModel>();
//Act
Controller.salvar(vm); // Problem here. (For convert ProcessoViewModel to Processo I use a AutoMaper. In repository needs destination to be a Mock<Processo>
var processo = Repository.Get(p => p.DataEntrada == vm.DataEntrada && p.ProximoAtendimento == vm.ProximoAtendimento);
//Asserts
processo.Should().NotBeNull();
processo.Passo.Should().NotBeNull();
}
Questions
We create a list of 10 Passo where each Passo is actually is a Mock<>, great! But:
For each Passo have a list of 5 'Mock' items, and each Id should be 1, 2, 3, 4 and 5 (in that order). How to achieve this? How to obtain this list of IList<Mock<>> inside a Mock<> with Id already filled? That is, the configuration
passo.SetupGet(x => x.CheckListItens).Returns( ???
The responsible for creating objects in my controller, basically uses AutoMapper to convert my ViewModel object to an object that can be persisted Model in my repository:
model = Mapper.Map<TModel>(vm);
The problem is that my repository Fake can not save an object IEntity, just Mock<IEntity>. How to configure AutoMapper to always return a Mock<>?

Answer 1

Answer for Question 1: In case this helps, you can use a closure to maintain a running counter to use as an id. For example:
class MyTestClass
{
int _runningCounter = 0;
public void SomeTest()
{
/* ... some other code including mock creation ...*/
someMock.Setup(m => m.ReturnNewWidgetEntity())
.Returns(() => new WidgetEntity{ Id= ++_runningCounter });
}
}
Each time ReturnNewWidgetEntity is called on the mocked object, the Id property will be set to an increased number.
Answer for Question 2: I would suggest that rather than having a concrete dependency on the Mapper class, you replace this with an injected dependency on IMapperEngine. Richard Dingwall explains the technique here: http://richarddingwall.name/2009/05/07/mocking-out-automapper-with-dependency-injection/
Basically you register Mapper.Engine as the singleton implementation of IMapperEngine in your container and then in your unit tests mock it so that it gives you the required Mock<> classes.
I hope one or both of these answers at least give you food for thought. It was a bit difficult to follow your whole example, to be honest!