Configure IStartupFilters in FIFO order #653

src/Microsoft.AspNetCore.Hosting/Internal/WebHost.cs

@@ -162,7 +162,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
 
                 var startupFilters = _applicationServices.GetService<IEnumerable<IStartupFilter>>();
                 var configure = Startup.ConfigureDelegate;
-                foreach (var filter in startupFilters)
+                foreach (var filter in startupFilters.Reverse())
                 {
                     configure = filter.Configure(configure);
                 }

test/Microsoft.AspNetCore.Hosting.Tests/WebHostTests.cs

@@ -250,6 +250,53 @@ namespace Microsoft.AspNetCore.Hosting
             Assert.NotNull(host.Services.GetRequiredService<IOptions<object>>());
         }
 
+        [Fact]
+        public void ConfiguresStartupFiltersInCorrectOrder()
+        {
+            // Verify ordering
+            var configureOrder = 0;
+            var host = CreateBuilder()
+                .UseServer((IServerFactory)this)
+                .ConfigureServices(services =>
+                {
+                    services.AddTransient<IStartupFilter>(serviceProvider => new TestFilter(
+                        () => Assert.Equal(1, configureOrder++),
+                        () => Assert.Equal(2, configureOrder++),
+                        () => Assert.Equal(5, configureOrder++)));
+                    services.AddTransient<IStartupFilter>(serviceProvider => new TestFilter(
+                        () => Assert.Equal(0, configureOrder++),
+                        () => Assert.Equal(3, configureOrder++),
+                        () => Assert.Equal(4, configureOrder++)));
+                })
+                .Build();
+            Assert.Equal(6, configureOrder);
+        }
+
+        private class TestFilter : IStartupFilter
+        {
+            private readonly Action _verifyConfigureOrder;
+            private readonly Action _verifyBuildBeforeOrder;
+            private readonly Action _verifyBuildAfterOrder;
+
+            public TestFilter(Action verifyConfigureOrder, Action verifyBuildBeforeOrder, Action verifyBuildAfterOrder)
+            {
+                _verifyConfigureOrder = verifyConfigureOrder;
+                _verifyBuildBeforeOrder = verifyBuildBeforeOrder;
+                _verifyBuildAfterOrder = verifyBuildAfterOrder;
+            }
+
+            public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
+            {
+                _verifyConfigureOrder();
+                return builder =>
+                {
+                    _verifyBuildBeforeOrder();
+                    next(builder);
+                    _verifyBuildAfterOrder();
+                };
+            }
+        }
+
         [Fact]
         public void EnvDefaultsToProductionIfNoConfig()
         {

test/Microsoft.AspNetCore.TestHost.Tests/TestServerTests.cs

@@ -275,7 +275,7 @@ namespace Microsoft.AspNetCore.TestHost
             {
                 app.Run(context =>
                 {
-                    Assert.NotNull(context.RequestServices);
+                    Assert.Null(context.RequestServices);
                     return context.Response.WriteAsync("Success");
                 });
             })