单元测试使用windows身份验证的控制器

-------请参阅下面的更新，因为我现在已经为依赖注入和MOQ mocking框架的使用设置好了。我仍然想拆分我的存储库，这样它就不会直接依赖于在同一函数中提取windowsUser

---

我在一个内联网站点中有一个Web API，它填充了一个下拉列表。下拉列表后面的查询将windows用户名作为返回列表的参数。

我意识到我没有正确设置所有这些，因为我无法对其进行单元测试。我需要知道如何设置这些"应该"来允许单元测试，然后单元测试应该是什么样子。

附加信息：这是一个ASP.NET MVC 5应用程序。

接口

public interface ITestRepository
{
    HttpResponseMessage DropDownList();
}

库存

public class ExampleRepository : IExampleRepository
{
    //Accessing the data through Entity Framework
    private MyDatabaseEntities db = new MyDatabaseEntities();
    public HttpResponseMessage DropDownList()
    {
        //Get the current windows user
        string windowsUser =  HttpContext.Current.User.Identity.Name;
        //Pass the parameter to a procedure running a select query
        var sourceQuery = (from p in db.spDropDownList(windowsUser)
                           select p).ToList();
        string result = JsonConvert.SerializeObject(sourceQuery);
        var response = new HttpResponseMessage();
        response.Content = new StringContent(result, System.Text.Encoding.Unicode, "application/json");
        return response;            
    }
}

控制器

public class ExampleController : ApiController
{
    private IExampleRepository _exampleRepository;
    public ExampleController()
    {
        _exampleRepository = new ExampleRepository();
    }
    [HttpGet]
    public HttpResponseMessage DropDownList()
    {
        try
        {
            return _exampleRepository.DropDownList();
        }
        catch
        {
            throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound));
        }
    }
}

更新1

我已经根据BartoszKP的建议更新了我的控制器，以显示依赖注入。

更新的控制器

public class ExampleController : ApiController
{
    private IExampleRepository _exampleRepository;
    //Dependency Injection
    public ExampleController(IExampleRepository exampleRepository)
    {
        _exampleRepository = exampleRepository;
    }
    [HttpGet]
    public HttpResponseMessage DropDownList()
    {
        try
        {
            return _exampleRepository.DropDownList();
        }
        catch
        {
            throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound));
        }
    }
}

更新2

我决定使用MOQ作为单元测试的模拟框架。我能够测试一些简单的东西，比如下面的这将测试一个简单的方法，该方法不需要任何参数，也不包括windowsUser部分。

[TestMethod]
public void ExampleOfAnotherTest()
{
    //Arrange
    var mockRepository = new Mock<IExampleRepository>();
    mockRepository
        .Setup(x => x.DropDownList())
        .Returns(new HttpResponseMessage(HttpStatusCode.OK));
    ExampleController controller = new ExampleController(mockRepository.Object);
    controller.Request = new HttpRequestMessage();
    controller.Configuration = new HttpConfiguration();
    //Act            
    var response = controller.DropDownList();
    //Assert
    Assert.AreEqual(HttpStatusCode.OK, response.StatusCode);
}

我需要帮助测试DropDownList方法（其中包含获取windowsUser的代码）。我需要关于如何打破这种方法的建议。我知道这两部分不应该采用相同的方法。我不知道如何安排拆分windowsUser变量。我意识到这确实应该作为一个参数引入，但我不知道如何引入。

private IExampleRepository _exampleRepository;
public ExampleController(IExampleRepository exampleRepository)
{
    _exampleRepository = exampleRepository;
}

[TestFixture]
public class ExampleTestFixture
{
    private IExampleRepository CreateRepositoryStub(fake data)
    {
        var exampleRepositoryStub = ...; // create the stub with a mocking framework
        // make the stub return given fake data
        return exampleRepositoryStub;
    }
    [Test]
    public void GivenX_WhenDropDownListIsRequested_ReturnsY()
    {
        // Arrange
        var exampleRepositoryStub = CreateRepositoryStub(X);
        var exampleController = new ExampleController(exampleRepositoryStub);
        // Act
        var result = exampleController.DropDownList();
        // Assert
        Assert.That(result, Is.Equal(Y));
    }  
}

// Arrange
var exampleController
    = GivenAController()
      .WithFakeData(X);

public class Untestable
{
    public int CalculateSomethingRandom()
    {
        return new Random().Next() + new Random().Next();
    }
}

public class Untestable
{
    public int CalculateSomethingRandom()
    {
        return GetRandomNumber() + GetRandomNumber();
    }
    protected virtual int GetRandomNumber()
    {
        return new Random().Next();
    }
}

public class Testable : Untestable
{
    protected override int GetRandomNumber()
    {
        // You can return whatever you want for your test here,
        // it depends on what type of behaviour you are faking.
        // You can easily inject values here via a constructor or
        // some public field in the subclass. You can also add
        // counters for times method was called, save the args etc.
        return 4;
    }
}