設置模擬配置讀取器時出錯

Question

我正在嘗試通過編寫一些簡單的單元測試來學習Moq。他們中有些人有一類叫做AppSettingsReader做：

public class BackgroundCheckServiceAppSettingsReader : IBackgroundCheckServiceAppSettingsReader 
{ 
    private string _someAppSetting; 

    public BackgroundCheckServiceAppSettingsReader(IWorkHandlerConfigReader configReader) 
    { 
     if (configReader.AppSettingsSection.Settings["SomeAppSetting"] != null) 
      this._someAppSetting = configReader.AppSettingsSection.Settings["SomeAppSetting"].Value; 
    }   

    public string SomeAppSetting 
    { 
     get { return _someAppSetting; } 
    } 
} 

的類接口的定義是這樣的：

public interface IBackgroundCheckServiceAppSettingsReader 
{ 
    string SomeAppSetting { get; } 
} 

而且IWorkHandlerConfigReader（我沒有權限修改）是定義像這樣：

public interface IWorkHandlerConfigReader 
{ 
    AppSettingsSection AppSettingsSection { get; } 
    ConnectionStringsSection ConnectionStringsSection { get; } 
    ConfigurationSectionCollection Sections { get; } 

    ConfigurationSection GetSection(string sectionName); 
} 

當我寫單元測試，我創建了IWorkHandlerConfigReader的Mock並嘗試建立預期b ehavior：

//Arrange 
string expectedReturnValue = "This_is_from_the_app_settings"; 
var configReaderMock = new Mock<IWorkHandlerConfigReader>(); 

configReaderMock.Setup(cr => cr.AppSettingsSection.Settings["SomeAppSetting"].Value).Returns(expectedReturnValue); 

//Act 
var reader = new BackgroundCheckServiceAppSettingsReader(configReaderMock.Object); 
var result = reader.SomeAppSetting; 

//Assert 
Assert.Equal(expectedReturnValue, result); 

這將編譯，但是當我運行測試，我看到以下錯誤：System.NotSupportedException : Invalid setup on a non-virtual (overridable in VB) member: cr => cr.AppSettingsSection.Settings["SomeAppSetting"].Value

有另一種方式比模擬對象來處理這個其他？我誤解它應該如何使用？

Answer 1

您實際上是在詢問AppSettingsSection實例的依賴關係。所以，你應該設置這個屬性getter返回一些你需要的數據部分實例：

// Arrange 
string expectedReturnValue = "This_is_from_the_app_settings"; 
var appSettings = new AppSettingsSection(); 
appSettings.Settings.Add("SomeAppSetting", expectedReturnValue); 

var configReaderMock = new Mock<IWorkHandlerConfigReader>(); 
configReaderMock.Setup(cr => cr.AppSettingsSection).Returns(appSettings); 
var reader = new BackgroundCheckServiceAppSettingsReader(configReaderMock.Object); 

// Act 
var result = reader.SomeAppSetting; 

// Assert 
Assert.Equal(expectedReturnValue, result);