增加支持Autofac的http单元测试

fix issue #I50DRR

OpenAuth.WebApi/Test/CustomServiceProviderFactory.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using Autofac;
+using Autofac.Extensions.DependencyInjection;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace OpenAuth.WebApi.Test
+{
+    /// <summary>
+    /// Based upon https://github.com/dotnet/aspnetcore/issues/14907#issuecomment-620750841 - only necessary because of an issue in ASP.NET Core
+    /// </summary>
+    public class CustomServiceProviderFactory : IServiceProviderFactory<ContainerBuilder>
+    {
+        private AutofacServiceProviderFactory _wrapped;
+        private IServiceCollection _services;
+
+        public CustomServiceProviderFactory()
+        {
+            _wrapped = new AutofacServiceProviderFactory();
+        }
+
+        public ContainerBuilder CreateBuilder(IServiceCollection services)
+        {
+            // Store the services for later.
+            _services = services;
+
+            return _wrapped.CreateBuilder(services);
+        }
+
+        public IServiceProvider CreateServiceProvider(ContainerBuilder containerBuilder)
+        {
+            var sp = _services.BuildServiceProvider();
+#pragma warning disable CS0612 // Type or member is obsolete
+            var filters = sp.GetRequiredService<IEnumerable<IStartupConfigureContainerFilter<ContainerBuilder>>>();
+#pragma warning restore CS0612 // Type or member is obsolete
+
+            foreach (var filter in filters)
+            {
+                filter.ConfigureContainer(b => { })(containerBuilder);
+            }
+
+            return _wrapped.CreateServiceProvider(containerBuilder);
+        }        
+    }
+}