RDF test migration for some response test cases. (dotnet#48611)

Author: mitchdenny

src/Http/Http.Extensions/gen/StaticRouteHandlerModel/Emitters/EndpointJsonResponseEmitter.cs

@@ -9,7 +9,7 @@ internal static void EmitJsonPreparation(this EndpointResponse endpointResponse,
     {
         if (endpointResponse.IsSerializableJsonResponse(out var responseType))
         {
-            var typeName = responseType.ToDisplayString(EmitterConstants.DisplayFormat);
+            var typeName = responseType.ToDisplayString(EmitterConstants.DisplayFormatWithoutNullability);
 
             codeWriter.WriteLine("var serializerOptions = serviceProvider?.GetService<IOptions<JsonOptions>>()?.Value.SerializerOptions ?? new JsonOptions().SerializerOptions;");
             codeWriter.WriteLine($"var jsonTypeInfo =  (JsonTypeInfo<{typeName}>)serializerOptions.GetTypeInfo(typeof({typeName}));");

src/Http/Http.Extensions/gen/StaticRouteHandlerModel/EndpointResponse.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Linq;
 using Microsoft.AspNetCore.Analyzers.RouteEmbeddedLanguage.Infrastructure;
 using Microsoft.AspNetCore.App.Analyzers.Infrastructure;
 using Microsoft.AspNetCore.Http.RequestDelegateGenerator.StaticRouteHandlerModel.Emitters;
@@ -34,7 +33,7 @@ internal EndpointResponse(IMethodSymbol method, WellKnownTypes wellKnownTypes)
         HasNoResponse = method.ReturnsVoid || awaitableIsVoid;
         IsIResult = GetIsIResult();
         IsSerializable = GetIsSerializable();
-        ContentType = GetContentType(method);
+        ContentType = GetContentType();
         IsAnonymousType = method.ReturnType.IsAnonymousType;
         IsEndpointMetadataProvider = ImplementsIEndpointMetadataProvider(ResponseType, wellKnownTypes);
     }
@@ -84,18 +83,19 @@ private bool GetIsIResult()
             SymbolEqualityComparer.Default.Equals(ResponseType, resultType);
     }
 
-    private string? GetContentType(IMethodSymbol method)
+    private string? GetContentType()
     {
         // `void` returning methods do not have a Content-Type.
         // We don't have a strategy for resolving a Content-Type
         // from an IResult. Typically, this would be done via an
         // IEndpointMetadataProvider so we don't need to set a
         // Content-Type here.
-        if (method.ReturnsVoid || IsIResult)
+        if (IsIResult || HasNoResponse)
         {
             return null;
         }
-        return method.ReturnType.SpecialType is SpecialType.System_String ? "text/plain" : "application/json";
+
+        return ResponseType!.SpecialType is SpecialType.System_String ? "text/plain; charset=utf-8" : "application/json";
     }
 
     public override bool Equals(object obj)

src/Http/Http.Extensions/gen/StaticRouteHandlerModel/StaticRouteHandlerModel.Emitter.cs

@@ -76,10 +76,6 @@ public static void EmitRequestHandler(this Endpoint endpoint, CodeWriter codeWri
         {
             return;
         }
-        if (!endpoint.Response.HasNoResponse && endpoint.Response is { ContentType: { } contentType })
-        {
-            codeWriter.WriteLine($@"httpContext.Response.ContentType ??= ""{contentType}"";");
-        }
         if (!endpoint.Response.HasNoResponse)
         {
             codeWriter.Write("var result = ");
@@ -89,6 +85,9 @@ public static void EmitRequestHandler(this Endpoint endpoint, CodeWriter codeWri
             codeWriter.Write("await ");
         }
         codeWriter.WriteLine($"handler({endpoint.EmitArgumentList()});");
+
+        endpoint.Response.EmitHttpResponseContentType(codeWriter);
+
         if (!endpoint.Response.HasNoResponse)
         {
             codeWriter.WriteLine(endpoint.Response.EmitResponseWritingCall(endpoint.IsAwaitable));
@@ -97,9 +96,27 @@ public static void EmitRequestHandler(this Endpoint endpoint, CodeWriter codeWri
         {
             codeWriter.WriteLine("return Task.CompletedTask;");
         }
+
         codeWriter.EndBlock(); // End handler method block
     }
 
+    private static void EmitHttpResponseContentType(this EndpointResponse endpointResponse, CodeWriter codeWriter)
+    {
+        if (!endpointResponse.HasNoResponse
+            && endpointResponse.ResponseType is { } responseType
+            && (responseType.SpecialType == SpecialType.System_Object || responseType.SpecialType == SpecialType.System_String))
+        {
+            codeWriter.WriteLine("if (result is string)");
+            codeWriter.StartBlock();
+            codeWriter.WriteLine($@"httpContext.Response.ContentType ??= ""text/plain; charset=utf-8"";");
+            codeWriter.EndBlock();
+            codeWriter.WriteLine("else");
+            codeWriter.StartBlock();
+            codeWriter.WriteLine($@"httpContext.Response.ContentType ??= ""application/json; charset=utf-8"";");
+            codeWriter.EndBlock();
+        }
+    }
+
     private static string EmitResponseWritingCall(this EndpointResponse endpointResponse, bool isAwaitable)
     {
         var returnOrAwait = isAwaitable ? "await" : "return";
@@ -183,7 +200,7 @@ private static void EmitBuiltinResponseTypeMetadata(this Endpoint endpoint, Code
         }
         else
         {
-            codeWriter.WriteLine($"options.EndpointBuilder.Metadata.Add(new GeneratedProducesResponseTypeMetadata(type: typeof({responseType.ToDisplayString(EmitterConstants.DisplayFormat)}), statusCode: StatusCodes.Status200OK, contentTypes: GeneratedMetadataConstants.JsonContentType));");
+            codeWriter.WriteLine($"options.EndpointBuilder.Metadata.Add(new GeneratedProducesResponseTypeMetadata(type: typeof({responseType.ToDisplayString(EmitterConstants.DisplayFormatWithoutNullability)}), statusCode: StatusCodes.Status200OK, contentTypes: GeneratedMetadataConstants.JsonContentType));");
         }
     }