Switch back to libuv as the default transport (#2257)

* Switch back to libuv as the default transport

src/Kestrel/WebHostBuilderKestrelExtensions.cs

@@ -5,9 +5,8 @@ using System;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
-using Microsoft.AspNetCore.Server.Kestrel.Internal;
 using Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal;
-using Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets;
+using Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
@@ -30,7 +29,7 @@ namespace Microsoft.AspNetCore.Hosting
             return hostBuilder.ConfigureServices(services =>
             {
                 // Don't override an already-configured transport
-                services.TryAddSingleton<ITransportFactory, SocketTransportFactory>();
+                services.TryAddSingleton<ITransportFactory, LibuvTransportFactory>();
 
                 services.AddTransient<IConfigureOptions<KestrelServerOptions>, KestrelServerOptionsSetup>();
                 services.AddSingleton<IServer, KestrelServer>();

test/Kestrel.Tests/WebHostBuilderKestrelExtensionsTests.cs

@@ -3,6 +3,9 @@
 
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
+using Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal;
+using Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv;
+using Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets;
 using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 
@@ -46,5 +49,51 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Tests
             // Act
             hostBuilder.Build();
         }
+
+        [Fact]
+        public void LibuvIsTheDefaultTransport()
+        {
+            var hostBuilder = new WebHostBuilder()
+                .UseKestrel()
+                .Configure(app => { });
+
+            Assert.IsType<LibuvTransportFactory>(hostBuilder.Build().Services.GetService<ITransportFactory>());
+        }
+
+        [Fact]
+        public void LibuvTransportCanBeManuallySelectedIndependentOfOrder()
+        {
+            var hostBuilder = new WebHostBuilder()
+                .UseKestrel()
+                .UseLibuv()
+                .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 SocketsTransportCanBeManuallySelectedIndependentOfOrder()
+        {
+            var hostBuilder = new WebHostBuilder()
+                .UseKestrel()
+                .UseSockets()
+                .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>());
+        }
     }
 }