使用moq模拟ChannelFactory时出现TargetInvocationException

Question

嘲笑ChannelFactory<IService>时为什么抛出TargetInvocationException？

public interface IService
{
void Do();
}
public class Service : IService
{
private ChannelFactory<IRemoteService> factory;
public Service(ChannelFactory<IRemoteService> factory)
{
this.factory = factory;
}
public void Do()
{
using (var remote = factory.CreateChannel())
{
remote.DoRemote();
}
}
}
[TestFixture]
public class ChannelFactoryMoqTest
{
private IService service;
private Mock<ChannelFactory<IRemoteService>> factory;
[Test]
public void Test()
{
this.factory = new Mock<ChannelFactory<IRemoteService>>();
this.service = new Service(this.factory.Object);
// Calling Object on this.factory throws TargetInvocationException
}
}

我想使用ChannelFactory依赖项而不是简单的IRemoteService，因为在我看来，在并发性方面，每次调用创建Service实例更安全。

以下是异常堆栈跟踪：

System.Reflection.TargetInvocationException was unhandled by user code
HResult=-2146232828
Message=Exception has been thrown by the target of an invocation.
Source=mscorlib
StackTrace:
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)
at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
at System.Activator.CreateInstance(Type type, Object[] args)
at Castle.DynamicProxy.ProxyGenerator.CreateClassProxyInstance(Type proxyType, List`1 proxyArguments, Type classToProxy, Object[] constructorArguments)
at Castle.DynamicProxy.ProxyGenerator.CreateClassProxy(Type classToProxy, Type[] additionalInterfacesToProxy, ProxyGenerationOptions options, Object[] constructorArguments, IInterceptor[] interceptors)
at Moq.Proxy.CastleProxyFactory.CreateProxy(Type mockType, ICallInterceptor interceptor, Type[] interfaces, Object[] arguments)
at Moq.Mock`1.<InitializeInstance>b__2()
at Moq.PexProtector.Invoke(Action action)
at Moq.Mock`1.InitializeInstance()
at Moq.Mock`1.OnGetObject()
at Moq.Mock.GetObject()
at Moq.Mock.get_Object()
at Moq.Mock`1.get_Object()
at TR.Eikon.Services.AppVersion.Tests.Workflows.ChannelFactoryMoqTest.Test() in d:Temp.cs:line 61
InnerException: System.NullReferenceException
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=System.ServiceModel
StackTrace:
at System.ServiceModel.ChannelFactory.EnsureSecurityCredentialsManager(ServiceEndpoint endpoint)
at System.ServiceModel.ChannelFactory.InitializeEndpoint(String configurationName, EndpointAddress address)
at System.ServiceModel.ChannelFactory`1..ctor()
at Castle.Proxies.ChannelFactory`1Proxy..ctor(IInterceptor[] )
InnerException: 

Answer 1

您收到该错误是因为ChannelFactory正试图为与其关联的不存在的端点创建实际代理。

我的建议是将ChannelFactory<IRemoteService>与客户端隐藏/隔离在您控制的接口后面，这样您就可以更好地管理所需的API。通过这种方式，您可以替换工厂，为客户端提供一个创建mock而不是真实代理的工厂。

public interface IMyChannelFactory<TChannel> {
TChannel CreateChannel();
}

其可以稍后包装CCD_ 8的实际实例。。。

public class ChannelFactoryWrapper<TChannel> : IMyChannelFactory<TChannel> {
private ChannelFactory<TChannel> factory;
public ChannelFactoryWrapper(ChannelFactory<TChannel> factory) {
this.factory = factory;
}
public TChannel CreateChannel() {
return factory.CreateChannel();
}
}

重构后的服务类将引用新的可模拟接口。。。

public class Service : IService {
private IMyChannelFactory<IRemoteService> factory;
public Service(IMyChannelFactory<IRemoteService> factory) {
this.factory = factory;
}
public void Do() {
using (var remote = factory.CreateChannel()) {
remote.DoRemote();
}
}
}

然后可以对您的测试进行相应的重构和测试。。。

[Test]
public void Should_Mock_ChannelFactory() {
//Arrange
var remoteService = new Mock<IRemoteService>();
remoteService.Setup(m => m.DoRemote()).Verifiable();
var factory = new Mock<IMyChannelFactory<IRemoteService>>();
factory.Setup(f => f.CreateChannel()).Returns(remoteService.Object).Verifiable();
var service = new Service(factory.Object);
//Act
service.Do();
//Assert
remoteService.Verify();
factory.Verify();
}