From d458a510648e0120b1fb30e962f1343a2d3cfc53 Mon Sep 17 00:00:00 2001
From: Stephen Halter <halter73@gmail.com>
Date: Tue, 16 Jan 2018 14:55:27 -0800
Subject: [PATCH] Fix typo + tests

---
 .../WebHostBuilderKestrelExtensions.cs        |  3 ++-
 .../WebHostBuilderKestrelExtensionsTests.cs   | 19 ++++++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/Kestrel/WebHostBuilderKestrelExtensions.cs b/src/Kestrel/WebHostBuilderKestrelExtensions.cs
index 5662a807d..70b1a34d7 100644
--- a/src/Kestrel/WebHostBuilderKestrelExtensions.cs
+++ b/src/Kestrel/WebHostBuilderKestrelExtensions.cs
@@ -8,6 +8,7 @@
 using Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal;
 using Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Hosting
@@ -28,7 +29,7 @@ public static IWebHostBuilder UseKestrel(this IWebHostBuilder hostBuilder)
             return hostBuilder.ConfigureServices(services =>
             {
                 // Don't override an already-configured transport
-                services.AddSingleton<ITransportFactory, LibuvTransportFactory>();
+                services.TryAddSingleton<ITransportFactory, LibuvTransportFactory>();
 
                 services.AddTransient<IConfigureOptions<KestrelServerOptions>, KestrelServerOptionsSetup>();
                 services.AddSingleton<IServer, KestrelServer>();
diff --git a/test/Kestrel.Tests/WebHostBuilderKestrelExtensionsTests.cs b/test/Kestrel.Tests/WebHostBuilderKestrelExtensionsTests.cs
index 86b79a699..3c10c1c0f 100644
--- a/test/Kestrel.Tests/WebHostBuilderKestrelExtensionsTests.cs
+++ b/test/Kestrel.Tests/WebHostBuilderKestrelExtensionsTests.cs
@@ -61,7 +61,7 @@ public void LibuvIsTheDefaultTransport()
         }
 
         [Fact]
-        public void LibuvTransportCanBeManuallySelected()
+        public void LibuvTransportCanBeManuallySelectedIndependentOfOrder()
         {
             var hostBuilder = new WebHostBuilder()
                 .UseKestrel()
@@ -69,11 +69,17 @@ public void LibuvTransportCanBeManuallySelected()
                 .Configure(app => { });
 
             Assert.IsType<LibuvTransportFactory>(hostBuilder.Build().Services.GetService<ITransportFactory>());
-        }
 
+            var hostBuilderReversed = new WebHostBuilder()
+                .UseLibuv()
+                .UseKestrel()
+                .Configure(app => { });
+
+            Assert.IsType<LibuvTransportFactory>(hostBuilderReversed.Build().Services.GetService<ITransportFactory>());
+        }
 
         [Fact]
-        public void SocketsTransportCanBeManuallySelected()
+        public void SocketsTransportCanBeManuallySelectedIndependentOfOrder()
         {
             var hostBuilder = new WebHostBuilder()
                 .UseKestrel()
@@ -81,6 +87,13 @@ public void SocketsTransportCanBeManuallySelected()
                 .Configure(app => { });
 
             Assert.IsType<SocketTransportFactory>(hostBuilder.Build().Services.GetService<ITransportFactory>());
+
+            var hostBuilderReversed = new WebHostBuilder()
+                .UseSockets()
+                .UseKestrel()
+                .Configure(app => { });
+
+            Assert.IsType<SocketTransportFactory>(hostBuilderReversed.Build().Services.GetService<ITransportFactory>());
         }
     }
 }