最近，我决定要集成测试WebApi 2应用程序。我决定将我的应用程序转换为OWIN兼容。我已经包含了所有的NuGet程序包，并将其与AutoFac中间件连接起来，依此类推。
但是，当我尝试使用HttpClient示例程序的Main方法中的in测试应用程序时，出现错误：
{
"Message":"An error has occurred.",
"ExceptionMessage":"An error occurred when trying to create a controller of type 'DinnerListController'. Make sure that the controller has a parameterless public constructor.",
"ExceptionType":"System.InvalidOperationException",
"StackTrace":" at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
"InnerException":{
"Message":"An error has occurred.",
"ExceptionMessage":"An exception was thrown while executing a resolve operation. See the InnerException for details. ---> Value cannot be null.\r\nParameter name: httpContext (See inner exception for details.)",
"ExceptionType":"Autofac.Core.DependencyResolutionException",
"StackTrace":" at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Lifetime.LifetimeScope.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable`1 parameters, Object& instance)\r\n at Autofac.ResolutionExtensions.ResolveOptionalService(IComponentContext context, Service service, IEnumerable`1 parameters)\r\n at Autofac.Integration.WebApi.AutofacWebApiDependencyScope.GetService(Type serviceType)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)",
"InnerException":{
"Message":"An error has occurred.",
"ExceptionMessage":"Value cannot be null.\r\nParameter name: httpContext",
"ExceptionType":"System.ArgumentNullException",
"StackTrace":" at System.Web.HttpContextWrapper..ctor(HttpContext httpContext)\r\n at Autofac.Integration.Mvc.AutofacWebTypesModule.<Load>b__0(IComponentContext c)\r\n at Autofac.RegistrationExtensions.<>c__DisplayClass10`1.<Register>b__f(IComponentContext c, IEnumerable`1 p)\r\n at Autofac.Builder.RegistrationBuilder.<>c__DisplayClass1`1.<ForDelegate>b__0(IComponentContext c, IEnumerable`1 p)\r\n at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)"
}
}
}
我找出了原因：我的服务依赖于HttpContextBase存储和从Cookie中提取内容：
public CookieUserService(HttpContextBase httpContext)
并且AutoFac无法初始化此类。当我尝试另一个实现时，如果没有HttpContextBase依赖，它会起作用。
所以问题是：有没有一种方法可以在使用OWIN时访问cookie，以便我可以重构服务并摆脱HttContextBase（和Web.dll）依赖关系？
切换到OWIN时，对System.Web等的所有依赖关系都将变为无效，因为它们会将应用程序与IIS托管环境紧密结合在一起。因此，AutoFac无法插入HttpContextBase对我的服务的依赖关系，因为它不能实例化。
为了解决该问题，HttpContextBase服务应该依赖于OWIN特定的接口，而不是使用System.Web依赖项（如），该接口提供应用程序和托管环境之间的抽象。
在我的特定情况下，我将服务更改为依赖于IOwinContext，如下所示：
public OwinCookieUserService(IOwinContext owinContext)
{
if (owinContext == null) throw new ArgumentNullException(nameof(owinContext));
_owinContext = owinContext;
}
添加两个附加的NuGet程序包后：
我可以在Startup类中将AutoFac和OWIN粘合在一起：
public class Startup
{
public void Configuration(IAppBuilder appBuilder)
{
var httpConfiguration = new HttpConfiguration();
...
AutoFacConfig.ConfigureAutoFac(httpConfiguration);
appBuilder.UseAutofacMiddleware(AutoFacConfig.Container);
appBuilder.UseAutofacWebApi(httpConfiguration);
appBuilder.UseWebApi(httpConfiguration);
}
}
在我的AutoFac映射中，我具有以下例程，用于在其中定义我的服务依赖项：
....
builder.RegisterType<OwinCookieUserService>().AsImplementedInterfaces().InstancePerLifetimeScope();
....
基本上就是这样！我不必专门为OWIN接口和类设置映射，它可以正常工作。我希望这将对将来的某些人有所帮助。
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