使用反射测试MEF部件 [英] Test MEF parts using reflection

问题描述

我有一个使用MEF的应用程序，我正在尝试为插件编写集成测试。 
我的代码是： -  
 
< pre lang =c＃> 
 public string Run（）
 {
 IFunction IUT = null; string Wanted =NewUser; 
 foreach（Lazy< IFunction，IFunctionData> func in functions）
 {
 if（func.Metadata.FunctionName == Wanted）IUT = func.Value; 
} 
 bool res = false; 
 res = TestOne（IUT）; 
 if（res）TestTwo（）; 
如果（res）返回Pass  -  NewUser Test; 
返回失败 -  NewUser测试; 
} 
 //普通新用户OK 
 private bool TestOne（IFunction IUT）
 {
 bool res = false; 
 //设置VM属性
 var VM = IUT.GetType（）; 
 PropertyInfo prop = VM.GetProperty（UserName）; prop.SetValue（prop，Smith）; 
 MethodInfo Method = VM.GetMethod（CreateNewUser）; 
 // ... 
 // ... 
返回res; 
} 

IFunction部分都是ViewModels，Run方法找到正确的OK。

我想做的是设置此VM的UserName属性，然后运行Create方法



我陷入了设置VM属性并运行方法的方法，我所拥有的不是工作。



我尝试了什么：



谷歌搜索想出了单位测试建议，但我需要测试与应用程序其余部分的集成

解决方案

您不需要使用MEF反射，只需输出&导入以共享数据 - 数据可以存在于主应用程序之外的DLL / EXE中。只要MEF可以编写，数据就会可见。这就是我们在另一个 MEF解决方案 [ ^ ]其中请求了插件系统的反射和当DLL / EXE被放入主应用程序的文件夹时，插件会自动加载。



因此，答案是创建一个类来单独保存用户详细信息class（repository），使用 PartCreationPolicy（CreationPolicy.Shared）定义 Export 。这将创建一个静态/共享对象。以下是一个示例：

  public   interface  IUserRepository 
 {
  string  UserName { get ;  set ; } 
} 
 
 [导出（ typeof （IUserRepository）），
 PartCreationPolicy（CreationPolicy.Shared）] 
  public   class  UserRepository：ObservableBase，IUserRepository 
 {
  private   string  userName =   ** Not Set **; 
 
  public   string  UserName 
 {
  get  = >  userName; 
  set  = > 设置（ ref  userName， value ）; 
} 
} 

注意：上面的代码不是线程安全的。如果你需要，我会留给你实现。



这是 ObservableBase 类：

  public   abstract   class  ObservableBase：INotifyPropertyChanged 
 {
  public   void 设置< TValue>（ ref  TValue字段，TValue newValue，[CallerMemberName] 字符串 propertyName = < span class =code-string> ）
 {
  if （EqualityComparer< TValue> .Default.Equals（field， default （TValue））||！field.Equals（newValue））
 { 
 field = newValue; 
 PropertyChanged？.Invoke（ this ， new  PropertyChangedEventArgs（propertyName））; 
} 
} 
 
  public   event  PropertyChangedEventHandler PropertyChanged ; 
 
  public   bool  IsInDesignMode =  >  DesignerProperties.GetIsInDesignMode（ new  DependencyObject（））; 
} 

现在你 import UserRepository ：

 [导入（ typeof （IUserRepository），RequiredCreationPolicy = CreationPolicy.Shared）] 
  public  IUserRepository Repo { get ;  set ; } 

...现在，只要使用上述 Import ，就会共享用户数据：

 Repo.UserName =   MainUser; 

您无需进行反射编码，因为它全部由MEF处理。享受！



PS：是的，MEF正在使用反射，所以你不必！ ;）

I have an application using MEF and am trying to write integration tests for the Plug-ins.
The code I have is:-

        <pre lang="c#">
        public string Run()
        {
            IFunction IUT = null; string Wanted = "NewUser";
            foreach (Lazy<IFunction, IFunctionData> func in functions)
            {
                if (func.Metadata.FunctionName == Wanted) IUT = func.Value;
            }
            bool res = false;
            res = TestOne(IUT);
            if (res) TestTwo();
            if (res) return "Pass -  NewUser Test";
            return "Fail -  NewUser Test";
        }
        // Normal New User OK
        private bool TestOne(IFunction IUT)
        {
            bool res = false;
            // Set up the VM properties
            var VM = IUT.GetType();
            PropertyInfo prop=VM.GetProperty("UserName");prop.SetValue(prop, "Smith");
            MethodInfo Method = VM.GetMethod("CreateNewUser");
            //...
            //...
            return res;
        }

The IFunction parts are all ViewModels and the Run method finds the correct one OK.
What I want to do is set the UserName property of this VM and then run the Create method

I am stuck on a way to set the VM properties and run the method, what I have does not work.

What I have tried:

Google searches came up with Unit test suggestions but I need to test integration with the rest of the application

解决方案

You don't need to use reflection with MEF, you simply Export & Import to share data - the data can exist in a DLL/EXE outside of the main app. So long as MEF can compose, the data will be visible. This is what we did in another MEF Solution[^] where reflection was requested for a plugin system and the plugins automatically load when the DLL/EXE is dropped into the main app's folder.

So, the answer is to create a class to hold your user details in a seperate class (repository), define the Export with a PartCreationPolicy(CreationPolicy.Shared). This will create a static/shared object. Here is an example:

public interface IUserRepository
{
    string UserName { get; set; }
}

[Export(typeof(IUserRepository)),
 PartCreationPolicy(CreationPolicy.Shared)]
public class UserRepository : ObservableBase, IUserRepository
{
    private string userName = "**Not Set**";

    public string UserName
    {
        get => userName;
        set => Set(ref userName, value);
    }
}

NOTE: The above code is not thread safe. I'll leave that up to you to implement if you require that.

Here is the ObservableBase class:

public abstract class ObservableBase : INotifyPropertyChanged
{
    public void Set<TValue>(ref TValue field, TValue newValue, [CallerMemberName] string propertyName = "")
    {
        if (EqualityComparer<TValue>.Default.Equals(field, default(TValue)) || !field.Equals(newValue))
        {
            field = newValue;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public bool IsInDesignMode => DesignerProperties.GetIsInDesignMode(new DependencyObject());
}

Now you import the UserRepository:

[Import(typeof(IUserRepository), RequiredCreationPolicy = CreationPolicy.Shared)]
public IUserRepository Repo { get; set; }

... and the user data is now shared whereever the above Import is used:

Repo.UserName = "MainUser";

No reflection coding by you is required as it is all handled by MEF. Enjoy!

PS: Yes, MEF is using reflection so you don't have to! ;)

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