如何使用 Moq 对具有三个依赖项的 MVC 控制器进行单元测试

Question

警告：我对 Moq、使用 Moq 进行单元测试和 TDD 是一个全新的概念。

我有一个具有三个依赖项的控制器。这是SomethingController的构造函数（等）：

public class SomethingController : Controller
    {
        private readonly ILogger<SomethingController> _logger;
        private readonly ISomethingRepository _something;
        private readonly IExceptionSvc _ex;

        public SomethingController(ILogger<SomethingController> logger,
            ISomethingRepository something,
            IExceptionSvc ex)
        {            
            _logger = logger;
            _something = something;
            _ex = ex;

        }

[HttpGet]
        [AllowAnonymous]
        public JsonResult GetStuff()
        {
            //intitialize list
            var stuffs = new List<StuffViewModel>();

        try
        {
            _logger.LogInformation("SomethingController: GetStuff() - Getting Stuff, sorted ascending.");

            //get the stuffs
            stuffs = _something.GetStuff();

            _logger.LogInformation("Retrieved {0} Stuffs.", stuffs.Count);
        }
        catch (Exception ex)
        {
            _logger.LogError("Error in SomethingController: GetStuff()", ex);
            return _ex.Http500ErrorReturn("GetStuff");
        }

        return Json(stuffs);
    }

}

现在，这里是每个依赖项的描述：

ILogger：这仅用于日志记录，通过 NLog 使用 Microsoft.Extensions.Logging。 ISomethingRepository：这完成了所有工作（嗯……它的实施，真的）。它调用数据库并获取内容。有一个名为 GetStuff() 的方法，它只返回一个 Stuffs 列表。这个 Repository 依赖于数据库，它通过构造函数注入到 repo 中。
IExceptionSvc：这只是一个愚蠢的小服务，它有一个方法可以将 JSON 格式的返回 500 错误响应返回给调用者。

我想测试 Controller 中的 GetStuff() 操作，它将调用 Repository 中的 GetStuff() 实现。

我目前在我的测试项目中有以下代码：

public void GetStuff_Is_Awesome()
        {
            Mock<ILogger<SomethingController>> logger = new Mock<ILogger<SomethingController>>();
            Mock<ISomethingRepository> something = new Mock<ISomethingRepository>();
            Mock <IExceptionSvc> ex = new Mock<IExceptionSvc>();
            SomethingController sc = new SomethingController(logger.Object, something.Object, ex.Object);

sc.GetStuff();

//...what now? What am I looking for? Am I going to see a list of stuffs here?

}

我只是想知道会发生什么？我是否在测试是否返回了 Stuffs 列表？我该如何测试？

这里是 Repository 中 GetStuff() 的实现（带有 repo 构造函数以供参考）：

private readonly ApplicationDbContext _context;
        private readonly ILogger<SomethingRepository> _logger;

        public SomethingRepository(ApplicationDbContext context,
            ILogger<SomethingRepository> logger)
        {
            _context = context;
            _logger = logger;
        }

public List<StuffViewModel> GetStuff()
        {
            List<StuffViewModel> stuffs = null;
            stuffs = _context.Stuffs.OrderBy(b => b.Name).Select(b => new StuffViewModel
                {
                    Id = b.Id,
                    Name = b.Name
                }).ToList();

return stuffs;
            }

Answer 1

把它想象成安排，行动断言

public void GetStuff_Is_Awesome()
{
    //arrange
    Mock<ILogger<SomethingController>> logger = new Mock<ILogger<SomethingController>>();
    Mock<ISomethingRepository> something = new Mock<ISomethingRepository>();
    Mock <IExceptionSvc> ex = new Mock<IExceptionSvc>();
    SomethingController sc = new SomethingController(logger.Object, something.Object, ex.Object);

    //act
    sc.GetStuff();

    //assert
}

所以，你想断言某事发生了，或者某事被调用了。

在不了解您的域或 ISomethingRepository 的情况下，您可以断言该方法已被调用：

something.Verify(m => m.MethodToCheckIfCalled());

其他选项是设置MethodToCheckIfCalled 的返回值并断言结果等...

假设您的控制器上有一个 GetStuff 方法，如下所示：

public ActionResult GetStuff()
{
    var data = _something.GetFromRepo();
    return View(data);
}

我会这样做：

public void GetStuff_Is_Awesome() //please don't call it this
{
    //arrange
    Mock<ILogger<SomethingController>> logger = new Mock<ILogger<SomethingController>>();
    Mock<ISomethingRepository> something = new Mock<ISomethingRepository>();
    Mock <IExceptionSvc> ex = new Mock<IExceptionSvc>();
    SomethingController sc = new SomethingController(logger.Object, something.Object, ex.Object);

    //setup your something mock GetFromRepo method to return a List of StuffViewModel
    something.Setup(m=> m.GetFromRepo())
        .Returns(new List<StuffViewModel>(){Id = 1, Name = "Test"});

    //act
    var result = sc.GetStuff();

    //assert

    //safely cast result to ViewResult
    var viewResult = result as ViewResult;

    Assert.IsNotNull(viewResult);
    Assert.IsNotNull(viewResult.Model); 

    // add additional checks on the Model.. loads of ways of doing this
    var viewResultModel = viewResut.Model as List<StuffViewModel>;

    Assert.AreEqual(1, viewResultModel.First().Id);
    Assert.AreEqual("Test", viewResultModel.First().Name);
}