跨程序集反射问题：IsAssignableFrom无法识别ICosmosJob实现

我正尝试让Test1测试用例正常运行。经排查，问题源于ICosmosJob与ICosmosApi_Shipment_Workorder位于不同程序集——将两者放在同一程序集时测试可正常执行。目前无法让typeof(ICosmosJob).IsAssignableFrom(t)返回true，求解决思路。

相关代码 #

[Test]
public void Test1()
{
    ServiceSettingsInfo.ApiConnectionString = "https://testcosmoscoreapi.bergerwebservices.com/";
    ServiceSettingsInfo.ServiceId = 1138;

    string assemblyPath = @"C:\Websites\CosmosJobProcessor\CosmosJobAssemblies\CosmosApi_Shipment_Workorder";

    ICosmosJob implementation = null;

    bool isimplemented = false;
    foreach (string assemblyFile in Directory.GetFiles(assemblyPath, "CosmosApi_Shipment_Workorder.dll"))
    {
        Assembly assembly = Assembly.LoadFrom(assemblyFile);
        var types = assembly.GetExportedTypes().Where(t => typeof(ICosmosJob).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract);
        // this works var types = assembly.GetExportedTypes().Where(t => typeof(ICosmosApi_Shipment_Workorder).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract);

        foreach (var type in types)
        {
            if (type.Name == "CosmosApi_Shipment_Workorder")
            {
                implementation = (ICosmosJob)Activator.CreateInstance(type);
                implementation.ExecuteAsync(new CosmosJobEntityDto(), "", CancellationToken.None).Wait();
                isimplemented = true;
                break;
            }
        }
    }

    Assert.That(isimplemented, Is.True);
}

public interface ICosmosJob
{
    Task<CosmosJobResponse> ExecuteAsync(CosmosJobEntityDto cosmosJobEntityDto, string url, CancellationToken stoppingToken);
}

public interface ICosmosApi_Shipment_Workorder: ICosmosJob
{
   ...
}

解决思路 #

• 排查程序集重复加载：测试项目和目标dll可能加载了两份ICosmosJob定义。因为Assembly.LoadFrom会加载指定路径的dll，若测试项目本身引用了包含ICosmosJob的程序集，会导致同一接口存在于不同程序集实例中，类型匹配失败。
  处理方式：改用Assembly.Load加载程序集强名称，或确保测试项目与目标dll引用的ICosmosJob程序集版本完全一致，避免重复加载。

• 验证类型继承链：在代码中输出目标类型的接口列表，确认ICosmosApi_Shipment_Workorder继承的ICosmosJob是否与测试项目中的为同一实例：

  foreach (var iface in type.GetInterfaces())
  {
      Console.WriteLine($"{type.Name} 实现了 {iface.FullName}，来自程序集 {iface.Assembly.FullName}");
  }
  

  若输出的程序集信息与测试项目中的ICosmosJob不一致，即可确认是重复加载问题。

• 通过全名匹配替代IsAssignableFrom：如果强名称加载有障碍，可以通过类型完整名称（含命名空间）来筛选：

  var targetIfaceFullName = typeof(ICosmosJob).FullName;
  var types = assembly.GetExportedTypes()
      .Where(t => !t.IsInterface && !t.IsAbstract 
          && t.GetInterfaces().Any(i => i.FullName == targetIfaceFullName));
  

• 添加程序集绑定重定向：若因版本不一致导致加载问题，可在测试项目的app.config中添加绑定重定向，确保所有引用指向同一版本的ICosmosJob程序集：

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="YourICosmosJobAssembly" publicKeyToken="公钥令牌" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-当前版本" newVersion="当前版本" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  

内容的提问来源于stack exchange，提问作者user1337493