Add a functional test for middleware after routing

It came up during routing discussions that we don't have any tests for
this scenario.

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RoutingTestsBase.cs

@@ -1265,6 +1265,19 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Equal(actionName, result.Action);
         }
 
+        [Fact]
+        public async Task CanRunMiddlewareAfterRouting()
+        {
+            // Act
+            var response = await Client.GetAsync("/afterrouting");
+
+            // Assert
+            await response.AssertStatusCodeAsync(HttpStatusCode.OK);
+            var content = await response.Content.ReadAsStringAsync();
+            Assert.Equal("Hello from middleware after routing", content);
+        }
+
+
         protected static LinkBuilder LinkFrom(string url)
         {
             return new LinkBuilder(url);

test/WebSites/RoutingWebSite/Startup.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.Extensions.DependencyInjection;
@@ -47,6 +48,11 @@ namespace RoutingWebSite
                     "RouteWithOptionalSegment",
                     "{controller}/{action}/{path?}");
             });
+
+            app.Map("/afterrouting", b => b.Run(c =>
+            {
+                return c.Response.WriteAsync("Hello from middleware after routing");
+            }));
         }
     }
 }

test/WebSites/RoutingWebSite/StartupWith21Compat.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.Extensions.DependencyInjection;
@@ -47,6 +48,11 @@ namespace RoutingWebSite
                     "RouteWithOptionalSegment",
                     "{controller}/{action}/{path?}");
             });
+
+            app.Map("/afterrouting", b => b.Run(c =>
+            {
+                return c.Response.WriteAsync("Hello from middleware after routing");
+            }));
         }
     }
 }