無法解析的接口使用Unity

Question

問題背景：

我使用統一解析類和它所有的依賴關係。

問題：

我想傳遞到通過統一的接口類型，我試圖做到這一點，如下所示類的構造函數：

public static IFacade UnityNewsFacadeResolver() 
    { 
      IUnityContainer unityContainer = new UnityContainer(); 
      unityContainer.RegisterType<IFacade, NewsFacade>(); 
      IFacade newsFacadeInstance = unityContainer.Resolve<NewsFacade>(); 

      return newsFacadeInstance; 
    } 

以下顯示Unity設置構造函數參數的'NewsFacade'類。值得注意的是傳遞一個「NewsStoryHandler」具體類型，我想在這個類是一款基於IE INewsStoryHandler的接口傳遞：

private INewsStoryHandler _NewsStoryHandler; 

    //*****Unity will only pass in a concrete implementation, I want to pass it as an interface but cannot:****** 
    public NewsFacade(NewsStoryHandler newsStoryHandler) 
    { 
     if (newsStoryHandler == null) 
     { 
      throw new Exception("newsStoryHandler is null at the constrcutor"); 
     } 

     _NewsStoryHandler = newsStoryHandler; 
    } 

目前統一不會解決，並通過在接口類型，它必須是具體實現如上所示。這意味着我不能在單元測試時模擬界面。

有人能告訴我爲什麼Unity不會解析並傳入基於其接口的類型？

Answer 1

Unity完全有能力根據其接口解析和提供類型。

要做到這一點，你必須確保統一知道什麼具體的實施提供，即

// Instruct unity to inject a NewsStoryHandler everywhere an INewsStoryHandler is specified 
unityContainer.RegisterType<INewsStoryHandler, NewsStoryHandler>(); 
var newsFacadeInstance = unityContainer.Resolve<NewsFacade>(); 

這工作假設你已經改變了你的NewsFacade構造有INewsStoryHandler類型的參數。

當涉及到單元測試，你就能夠嘲笑INewsStoryHandler使用起訂量，讓您的NewsFacade簡單，一個例子的測試：

// Setup and configure the mock 
var mockNewsStoryHandler = new Mock<INewsStoryHandler>(); 
mockNewsStoryHandler.Setup(h => h.GetAllStories()).Returns(Enumerable.Empty<NewsStory>()); 

// Inject the mock 
var newsFacade = new NewsFacade(mockNewsStoryHandler.Object); 
newsFacade.DoSomethingWithAllStories(); 

// Verify GetAllStories() was called exactly once 
mockNewsStoryHandler.Verify(h => h.GetAllStories(), Times.Once);