Mark WebHostBuilder class as obsolete

src/DataProtection/DataProtection/test/Microsoft.AspNetCore.DataProtection.Tests/HostingTests.cs

@@ -25,6 +25,7 @@ public async Task WebhostLoadsKeyRingBeforeServerStarts()
             .Returns(Mock.Of<IKeyRing>())
             .Callback(() => tcs.TrySetResult());
 
+#pragma warning disable CS0618 // Type or member is obsolete
         var builder = new WebHostBuilder()
             .UseStartup<TestStartup>()
             .ConfigureServices(s =>
@@ -33,6 +34,7 @@ public async Task WebhostLoadsKeyRingBeforeServerStarts()
                 .Replace(ServiceDescriptor.Singleton(mockKeyRing.Object))
                 .AddSingleton<IServer>(
                     new FakeServer(onStart: () => tcs.TrySetException(new InvalidOperationException("Server was started before key ring was initialized")))));
+#pragma warning restore CS0618 // Type or member is obsolete
 
         using (var host = builder.Build())
         {

src/DefaultBuilder/src/WebHost.cs

@@ -154,7 +154,9 @@ public static IWebHostBuilder CreateDefaultBuilder() =>
     /// <returns>The initialized <see cref="IWebHostBuilder"/>.</returns>
     public static IWebHostBuilder CreateDefaultBuilder(string[] args)
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         var builder = new WebHostBuilder();
+#pragma warning restore CS0618 // Type or member is obsolete
 
         if (string.IsNullOrEmpty(builder.GetSetting(WebHostDefaults.ContentRootKey)))
         {

src/Hosting/Hosting/src/WebHostBuilder.cs

@@ -20,6 +20,7 @@ namespace Microsoft.AspNetCore.Hosting;
 /// <summary>
 /// A builder for <see cref="IWebHost"/>
 /// </summary>
+[Obsolete("TODO: Add Obsolete message")]
 public class WebHostBuilder : IWebHostBuilder
 {
     private readonly HostingEnvironment _hostingEnvironment;

src/Hosting/Hosting/test/WebHostBuilderTests.cs

@@ -429,6 +429,7 @@ public void DoNotCaptureStartupErrorsByDefault(IWebHostBuilder builder)
     public void ServiceProviderDisposedOnBuildException()
     {
         var service = new DisposableService();
+#pragma warning disable CS0618 // Type or member is obsolete
         var hostBuilder = new WebHostBuilder()
             .UseServer(new TestServer())
             .ConfigureServices(services =>
@@ -437,6 +438,7 @@ public void ServiceProviderDisposedOnBuildException()
                 services.AddSingleton(sp => service);
             })
             .UseStartup<StartupWithResolvedDisposableThatThrows>();
+#pragma warning restore CS0618 // Type or member is obsolete
 
         Assert.Throws<InvalidOperationException>(() => hostBuilder.Build());
         Assert.True(service.Disposed);
@@ -1483,14 +1485,18 @@ private IWebHostBuilder CreateWebHostBuilder()
             .AddInMemoryCollection(vals);
         var config = builder.Build();
 
+#pragma warning disable CS0618 // Type or member is obsolete
         return new WebHostBuilder().UseConfiguration(config);
+#pragma warning restore CS0618 // Type or member is obsolete
     }
 
+#pragma warning disable CS0618 // Type or member is obsolete
     public static TheoryData<IWebHostBuilder> DefaultWebHostBuilders => new TheoryData<IWebHostBuilder>
         {
             new WebHostBuilder(),
             new GenericWebHostBuilderWrapper(new HostBuilder())
         };
+#pragma warning restore CS0618 // Type or member is obsolete
 
     public static TheoryData<IWebHostBuilder> DefaultWebHostBuildersWithConfig
     {
@@ -1506,10 +1512,12 @@ public static TheoryData<IWebHostBuilder> DefaultWebHostBuildersWithConfig
                 .AddInMemoryCollection(vals);
             var config = builder.Build();
 
+#pragma warning disable CS0618 // Type or member is obsolete
             return new TheoryData<IWebHostBuilder> {
                     new WebHostBuilder().UseConfiguration(config),
                     new GenericWebHostBuilderWrapper(new HostBuilder()).UseConfiguration(config)
                 };
+#pragma warning restore CS0618 // Type or member is obsolete
         }
     }
 

src/Hosting/Hosting/test/WebHostTests.cs

@@ -1103,7 +1103,9 @@ private IWebHost CreateHost(RequestDelegate requestDelegate)
 
     private IWebHostBuilder CreateBuilder(IConfiguration config = null)
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         return new WebHostBuilder().UseConfiguration(config ?? new ConfigurationBuilder().Build()).UseStartup("Microsoft.AspNetCore.Hosting.Tests");
+#pragma warning restore CS0618 // Type or member is obsolete
     }
 
     private static bool[] RegisterCallbacksThatThrow(IServiceCollection services)

src/Hosting/TestHost/test/ClientHandlerTests.cs

@@ -11,6 +11,7 @@
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.InternalTesting;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Net.Http.Headers;
 
@@ -691,19 +692,27 @@ public async Task ClientHandlerCreateContextWithDefaultRequestParameters()
     {
         // This logger will attempt to access information from HttpRequest once the HttpContext is created
         var logger = new VerifierLogger();
-        var builder = new WebHostBuilder()
-            .ConfigureServices(services =>
+        using var host = new HostBuilder()
+            .ConfigureWebHost(webHostBuilder =>
             {
-                services.AddSingleton<ILogger<IWebHost>>(logger);
+                webHostBuilder
+                    .UseTestServer()
+                    .ConfigureServices(services =>
+                    {
+                        services.AddSingleton<ILogger<IWebHost>>(logger);
+                    })
+                    .Configure(app =>
+                    {
+                        app.Run(context =>
+                        {
+                            return Task.FromResult(0);
+                        });
+                    });
             })
-            .Configure(app =>
-            {
-                app.Run(context =>
-                {
-                    return Task.FromResult(0);
-                });
-            });
-        var server = new TestServer(builder);
+            .Build();
+        var server = host.GetTestServer();
+
+        await host.StartAsync();
 
         // The HttpContext will be created and the logger will make sure that the HttpRequest exists and contains reasonable values
         var result = await server.CreateClient().GetStringAsync("/");