訪問實體數據庫的單元測試函數

Question

嘗試訪問實體框架的單元測試函數。所以我試圖把所有的實體代碼放到下面的測試函數中？然而它停止在Linq聲明中;顯然試圖訪問數據庫對它來說太過戲劇化了。也許一個解決方法是在基於sql lite或compact的單元測試函數中創建一個副本數據庫（反正它不是一個大的數據庫），那麼執行不必離開測試函數？這是可能的，我將如何實現它？

public void RetreiveKeyFnTest() 
    { 
     StegApp target = new StegApp(); // TODO: Initialize to an appropriate value 
     string username = "david"; // TODO: Initialize to an appropriate value 
     string password = "david1"; // TODO: Initialize to an appropriate value 
     string ConnectionString = ConfigurationManager.ConnectionStrings["DatabaseEntities"].ToString(); 
     var dataContext = new DatabaseEntities(ConnectionString); 
     var user = dataContext.Users.FirstOrDefault(u => u.Username.Equals(username) && u.Password.Equals(password)); 
     Assert.IsNotNull(user); 

     //target.RetreiveKeyFn(username, password); 
     //Assert.IsInstanceOfType(target.RetreiveLogs,typeof(DataAccess)); 
     //Assert.IsInstanceOfType(target.p); 
     //Assert.IsNotNull(target.RetreiveLogs.AuthenitcateCredentials(username,password)); 
     //Assert.Inconclusive("A method that does not return a value cannot be verified."); 
    } 

下面是代碼我試圖測試：

public void RetreiveKeyFn(string username, string password) 
    { 

     BusinessObjects.User p = RetreiveLogs.AuthenitcateCredentials(username,password); 
     if (p != null) 
     { 
      if (RetreiveLogs.RetreiveMessages(p.UserId) == null) 
      { 
       DisplayLogs.Text = "Sorry No messages for you recorded in Database, your correspondant might have chose not to record the entry"; 
      } 
      else 
      { 
       MessageBox.Show("LogId = " + RetreiveLogs.RetreiveMessages(p.UserId).LogId + "\n" + 
       "UserId = " + RetreiveLogs.RetreiveMessages(p.UserId).UserId + "\n" + 
       "Message Key = " + RetreiveLogs.RetreiveMessages(p.UserId).MessageKey + "\n" + "PictureId = " + RetreiveLogs.RetreiveMessages(p.UserId).PictureId + 
       " Date & time = " + RetreiveLogs.RetreiveMessages(p.UserId).SentDateTime); 
       DisplayLogs.Visible = true; 
      } 
     } 
     else 
     { 
      MessageBox.Show("Please enter your correct username and password in order to retreive either key, image or both from Databse"); 
     } 


    } 

Answer 1

我得到了我的單元測試，以做工精細的例子。我所犯的錯誤不是將app.config文件複製到測試項目中！儘管說實話，我預計Visual Studio會做到這一點。

Answer 2

首先，你應該能夠訪問同一個數據庫中測試應用程序作爲一個你用在主/實際應用。你只需要確保你的Test項目包含你自己的App.config中的連接字符串。

上下文的初始化應該在您的StegApp（）中的裏面中完成，或者您應該能夠從另一個範圍傳遞上下文到您的StegApp（）。從我讀到的代碼中，您的StegApp（）將無法訪問您創建的dataContext變量。

您對null用戶的測試已經發生在AuthenticateCredentials（）方法下的RetrieveKeyFn（）內部，因此不需要第一個「Assert.IsNotNull（user）」。我建議將您的用於UI行爲的RetrieveKeyFn業務邏輯分開，以便您可以輕鬆地進行單元測試。您可以綁定「Messagebox」操作來說一個只調用RetrieveKeyFn（）的按鈕單擊事件處理程序。我建議也許是這樣的：

public class StegApp 
{ 

     public DatabaseEntities context; 
     //other properties 

     public StegApp() 
     { 
      //assuming your DatabaseEntities class inherits from DbContext. 
      //You should create other constructors that allow you to set options 
      //like lazy loading and mappings 
      this.context = new DatabaseEntities(); 
     } 

     //ASSUMING YOUR RetrieveLogs.RetrieveMessages() function returns 
     //a Message object. replace this type with whatever type the 
     //RetrieveLogs.RetrieveMessages() method returns. 
     public Message RetrieveKeyFn (string username, string password) 
     { 

      BusinessObjects.User p = RetreiveLogs.AuthenitcateCredentials(username,password); 
      if (p != null) 
      { 
       var message = RetrieveLogs.RetrieveMessages(p.UserId); 
       if (message == null) 
        // handle behavior for no messages. In this case 
        // I will just create a new Message object with a -1 LogId 
        return new Message {LogId =-1}; 
       else 
        return message; 
      } 
      else 
       //handle behavior when the user is not authenticated. 
       //In this case I throw an exception 
       throw new Exception(); 

     } 

    //on your button click handler, do something like: 
    // try 
    // { 
    //  var message = RetrieveKeyFn(txtUsername.Text.Trim(), txtPassword.Text.Trim()); 
    //  if (message.LogId == -1) 
    //   DisplayLogs.Text = "Sorry No messages for you recorded in Database, your correspondant might have chose not to record the entry"; 
    //  else 
    //  { 
    //   MessageBox.Show("Log Id = " + message.LogId) 
    //   etc. etc. etc. 
    //  } 
    // } 
    // catch 
    // { 
    //  MessageBox.Show ("user is not authenticated"); 
    // } 

} 

當你做你的單元測試，記得有適當的配置字符串在測試項目App.Config中如果在app.config尚不存在，繼續前進並創建一個。您應該爲所有可能性（即1）創建測試用戶有效，您會收到消息，2）用戶有效，沒有消息，3）用戶無效）。

這裏有一個案例2

[TestMethod] 
    public void RetrieveKeyFnTest1() 
    { 
     StegApp target = new StegApp(); // this creates your context. I'm assuming it also creates your RetrieveLogs object, etc 
     var username = "UserWithNotMessages"; //this user should exist in your database but should not have any messages. You could insert this user as part of your TestInitialize method 
     var password = "UserWithNotMessagesPassword"; //this should be the proper password 
     var message = target.RetrieveKeyFn(username, password); 
     Assert.AreEqual (-1, message.LogId); 
    }