How to unit test ServiceStack?

Question

I love SS but I\'m scratching my head trying to unit test my business layer. I\'m new to unit testing andmocking and been reading up on NSubstitute as this looks like a fun moc

Answer 1

If you want to unit test a ServiceStack Service in isolation there are a couple of different approaches you can take. The base Service class itself is just a simple C# class which lets you define and inject dependencies manually or by using the built-in IOC container.

We'll illustrate both approaches using this simple unit test example that tests this simple Service:

DTOs

public class FindRockstars
{
   public int? Aged { get; set; }
   public bool? Alive { get; set; }
}

public class GetStatus
{
   public string LastName { get; set; }
}

public class RockstarStatus
{
   public int Age { get; set; }
   public bool Alive { get; set; }
}

public class Rockstar
{
   public int Id { get; set; }
   public string FirstName { get; set; }
   public string LastName { get; set; }
   public int? Age { get; set; }
}

Implementation

public class SimpleService : Service
{
   public IRockstarRepository RockstarRepository { get; set; }

   public List<Rockstar> Get(FindRockstars request)
   {
      return request.Aged.HasValue
          ? Db.Select<Rockstar>(q => q.Age == request.Aged.Value)
          : Db.Select<Rockstar>();
   }

   public RockstarStatus Get(GetStatus request)
   {
      var rockstar = RockstarRepository.GetByLastName(request.LastName);
      if (rockstar == null)
          throw HttpError.NotFound("'{0}' is not a Rockstar".Fmt(request.LastName));

      var status = new RockstarStatus
      {
          Alive = RockstarRepository.IsAlive(request.LastName)
      }.PopulateWith(rockstar); //Populates with matching fields

      return status;
   }
}

This Service provides 2 operations, FindRockstars which makes db queries directly in the service class itself, and GetStatus which uses a repository instead for all its Data access.

Using an in-memory database

If you're accessing Db from directly within your service implementation you're going to want to make use of a real DB given the ADO.NET IDbConnection requires a lot of effort to mock. You can do this in the same way you would register your dependencies in ServiceStack itself, by using the built-in IOC. For a unit test we can do this without an AppHost by just use a new Container in your TestFixtureSetup, e.g:

Test Setup

private ServiceStackHost appHost;

[TestFixtureSetUp]
public void TestFixtureSetUp()
{
    appHost = new BasicAppHost().Init();
    var container = appHost.Container;

    container.Register<IDbConnectionFactory>(
        new OrmLiteConnectionFactory(":memory:", SqliteDialect.Provider));

    container.RegisterAutoWiredAs<RockstarRepository, IRockstarRepository>();

    container.RegisterAutoWired<SimpleService>();

    using (var db = container.Resolve<IDbConnectionFactory>().Open())
    {
        db.DropAndCreateTable<Rockstar>();
        db.InsertAll(SeedData);
    }
}

[TestFixtureTearDown]
public void TestFixtureTearDown()
{
    appHost.Dispose();
}

With everything setup we can now test the service just like a normal C# class in isolation independently of ServiceStack itself:

[Test]
public void Using_in_memory_database()
{
    //Resolve the autowired service from IOC and set Resolver for the base class
    var service = appHost.Container.Resolve<SimpleService>(); 

    var rockstars = service.Get(new FindRockstars { Aged = 27 });

    rockstars.PrintDump(); //Print a dump of the results to Console

    Assert.That(rockstars.Count, Is.EqualTo(SeedData.Count(x => x.Age == 27)));

    var status = service.Get(new GetStatus { LastName = "Vedder" });
    Assert.That(status.Age, Is.EqualTo(48));
    Assert.That(status.Alive, Is.True);

    status = service.Get(new GetStatus { LastName = "Hendrix" });
    Assert.That(status.Age, Is.EqualTo(27));
    Assert.That(status.Alive, Is.False);

    Assert.Throws<HttpError>(() =>
        service.Get(new GetStatus { LastName = "Unknown" }));
}

Manually injecting dependencies

If you prefer your unit tests not to use an in-memory database, you can instead choose to mock your dependencies. In this example we'll use a stand-alone Mock, but you can reduce boilerplate by using mocking library like Moq instead.

public class RockstarRepositoryMock : IRockstarRepository
{
    public Rockstar GetByLastName(string lastName)
    {
        return lastName == "Vedder"
            ? new Rockstar(6, "Eddie", "Vedder", 48)
            : null;
    }

    public bool IsAlive(string lastName)
    {
        return lastName == "Grohl" || lastName == "Vedder";
    }
}

[Test]
public void Using_manual_dependency_injection()
{
    var service = new SimpleService
    {
        RockstarRepository = new RockstarRepositoryMock()
    };

    var status = service.Get(new GetStatus { LastName = "Vedder" });
    Assert.That(status.Age, Is.EqualTo(48));
    Assert.That(status.Alive, Is.True);

    Assert.Throws<HttpError>(() =>
        service.Get(new GetStatus { LastName = "Hendrix" }));
}

This example doesn't need a container as we're injecting all the dependencies manually. I've also added this example to the Testing wiki docs.