Added endpoint API explorer to default webhost (#33800)

* Added endpoint API explorer to default webhost
- This will allow discovery of API explorer metadata without an explicit call.
- Added API explorer tests

src/DefaultBuilder/DefaultBuilder.slnf

@@ -17,8 +17,14 @@
       "src\\Http\\Http.Features\\src\\Microsoft.AspNetCore.Http.Features.csproj",
       "src\\Http\\Http\\src\\Microsoft.AspNetCore.Http.csproj",
       "src\\Http\\WebUtilities\\src\\Microsoft.AspNetCore.WebUtilities.csproj",
+      "src\\Middleware\\ResponseCaching.Abstractions\\src\\Microsoft.AspNetCore.ResponseCaching.Abstractions.csproj",
       "src\\Middleware\\StaticFiles\\src\\Microsoft.AspNetCore.StaticFiles.csproj",
-      "src\\ObjectPool\\src\\Microsoft.Extensions.ObjectPool.csproj"
+      "src\\Mvc\\Mvc.Abstractions\\src\\Microsoft.AspNetCore.Mvc.Abstractions.csproj",
+      "src\\Mvc\\Mvc.ApiExplorer\\src\\Microsoft.AspNetCore.Mvc.ApiExplorer.csproj",
+      "src\\Mvc\\Mvc.Core\\src\\Microsoft.AspNetCore.Mvc.Core.csproj",
+      "src\\ObjectPool\\src\\Microsoft.Extensions.ObjectPool.csproj",
+      "src\\Security\\Authentication\\Core\\src\\Microsoft.AspNetCore.Authentication.csproj",
+      "src\\Security\\Authorization\\Policy\\src\\Microsoft.AspNetCore.Authorization.Policy.csproj"
     ]
   }
 }
\ No newline at end of file

src/DefaultBuilder/src/Microsoft.AspNetCore.csproj

@@ -18,6 +18,7 @@
     <Reference Include="Microsoft.AspNetCore.Server.IIS" />
     <Reference Include="Microsoft.AspNetCore.Server.IISIntegration" />
     <Reference Include="Microsoft.AspNetCore.Server.Kestrel" />
+    <Reference Include="Microsoft.AspNetCore.Mvc.ApiExplorer" />
     <Reference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" />
     <Reference Include="Microsoft.Extensions.Configuration.FileExtensions" />
     <Reference Include="Microsoft.Extensions.Configuration.Json" />

src/DefaultBuilder/src/WebHost.cs

@@ -259,6 +259,7 @@ namespace Microsoft.AspNetCore
                 }
 
                 services.AddRouting();
+                services.AddEndpointsApiExplorer();
             })
             .UseIIS()
             .UseIISIntegration();

src/DefaultBuilder/test/Microsoft.AspNetCore.Tests/WebApplicationTests.cs

@@ -15,6 +15,7 @@ using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Hosting.Server.Features;
 using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.AspNetCore.Testing;
@@ -269,6 +270,14 @@ namespace Microsoft.AspNetCore.Tests
             Assert.NotNull(linkGenerator);
         }
 
+        [Fact]
+        public void WebApplicationCreate_RegistersApiExplorerForEndpoints()
+        {
+            var app = WebApplication.Create();
+            var apiDescriptionProvider = app.Services.GetService(typeof(IApiDescriptionProvider));
+            Assert.NotNull(apiDescriptionProvider);
+        }
+
         [Fact]
         public void WebApplicationCreate_RegistersEventSourceLogger()
         {

src/DefaultBuilder/test/Microsoft.AspNetCore.Tests/WebHostTests.cs

@@ -11,6 +11,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.HostFiltering;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.AspNetCore.Testing;
@@ -99,6 +100,17 @@ namespace Microsoft.AspNetCore.Tests
             Assert.NotNull(linkGenerator);
         }
 
+        [Fact]
+        public void CreateDefaultBuilder_RegistersApiExplorer()
+        {
+            var host = WebHost.CreateDefaultBuilder()
+                .Configure(_ => { })
+                .Build();
+
+            var apiDescriptionProvider = host.Services.GetService(typeof(IApiDescriptionProvider));
+            Assert.NotNull(apiDescriptionProvider);
+        }
+
         [Fact]
         public void CreateDefaultBuilder_RegistersEventSourceLogger()
         {