got identity server access token acceptance test working, created factory for choosing auth handlers, a creator for making the auth handlers, some general refactoring...next step is injecting the config for the auth handler creator in some way or just passing it in

src/Ocelot.Library/Infrastructure/Authentication/AuthenticationHandler.cs

@@ -0,0 +1,16 @@
+using Microsoft.AspNetCore.Http;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    public class AuthenticationHandler
+    {
+        public AuthenticationHandler(string provider, RequestDelegate handler)
+        {
+            Provider = provider;
+            Handler = handler;
+        }
+
+        public string Provider { get; private set; }
+        public RequestDelegate Handler { get; private set; }
+    }
+}

src/Ocelot.Library/Infrastructure/Authentication/AuthenticationHandlerCreator.cs

@@ -0,0 +1,32 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    /// <summary>
+    /// Cannot unit test things in this class due to use of extension methods
+    /// </summary>
+    public class AuthenticationHandlerCreator : IAuthenticationHandlerCreator
+    {
+        public Response<RequestDelegate> CreateIdentityServerAuthenticationHandler(IApplicationBuilder app)
+        {
+            var builder = app.New();
+
+            builder.UseIdentityServerAuthentication(new IdentityServerAuthenticationOptions
+            {
+                //todo sort these options out
+                Authority = "http://localhost:51888",
+                ScopeName = "api",
+
+                RequireHttpsMetadata = false
+            });
+
+            builder.UseMvc();
+
+            var authenticationNext = builder.Build();
+
+            return new OkResponse<RequestDelegate>(authenticationNext);
+        }
+    }
+}

src/Ocelot.Library/Infrastructure/Authentication/AuthenticationProviderFactory.cs

@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Builder;
+using Ocelot.Library.Infrastructure.Errors;
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    public class AuthenticationProviderFactory : IAuthenticationProviderFactory
+    {
+        private readonly IAuthenticationHandlerCreator _creator;
+
+        public AuthenticationProviderFactory(IAuthenticationHandlerCreator creator)
+        {
+            _creator = creator;
+        }
+
+        public Response<AuthenticationHandler> Get(string provider, IApplicationBuilder app)
+        {
+            var handler = _creator.CreateIdentityServerAuthenticationHandler(app);
+
+            if (!handler.IsError)
+            {
+                return new OkResponse<AuthenticationHandler>(new AuthenticationHandler(provider, handler.Data));
+            }
+
+            return new ErrorResponse<AuthenticationHandler>(new List<Error>
+            {
+                new UnableToCreateAuthenticationHandlerError($"Unable to create authentication handler for {provider}")
+            });
+        }
+    }
+}

src/Ocelot.Library/Infrastructure/Authentication/IAuthenticationHandlerCreator.cs

@@ -0,0 +1,11 @@
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    public interface IAuthenticationHandlerCreator
+    {
+        Response<RequestDelegate> CreateIdentityServerAuthenticationHandler(IApplicationBuilder app);
+    }
+}

src/Ocelot.Library/Infrastructure/Authentication/IAuthenticationProviderFactory.cs

@@ -0,0 +1,10 @@
+using Microsoft.AspNetCore.Builder;
+using Ocelot.Library.Infrastructure.Responses;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    public interface IAuthenticationProviderFactory
+    {
+        Response<AuthenticationHandler> Get(string provider, IApplicationBuilder app);
+    }
+}

src/Ocelot.Library/Infrastructure/Authentication/UnableToCreateAuthenticationHandlerError.cs

@@ -0,0 +1,12 @@
+using Ocelot.Library.Infrastructure.Errors;
+
+namespace Ocelot.Library.Infrastructure.Authentication
+{
+    public class UnableToCreateAuthenticationHandlerError : Error
+    {
+        public UnableToCreateAuthenticationHandlerError(string message) 
+            : base(message, OcelotErrorCode.UnableToCreateAuthenticationHandlerError)
+        {
+        }
+    }
+}