[release/8.0] Fix casing of ProblemDetails for RFC compliance

src/Http/Http.Abstractions/src/ProblemDetails/HttpValidationProblemDetails.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text.Json.Serialization;
 using Microsoft.AspNetCore.Mvc;
 
 namespace Microsoft.AspNetCore.Http;
@@ -36,5 +37,6 @@ private HttpValidationProblemDetails(Dictionary<string, string[]> errors)
     /// <summary>
     /// Gets the validation errors associated with this instance of <see cref="HttpValidationProblemDetails"/>.
     /// </summary>
+    [JsonPropertyName("errors")]
     public IDictionary<string, string[]> Errors { get; set; } = new Dictionary<string, string[]>(StringComparer.Ordinal);
 }

src/Http/Http.Abstractions/src/ProblemDetails/ProblemDetails.cs

@@ -18,6 +18,7 @@ public class ProblemDetails
     /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyOrder(-5)]
+    [JsonPropertyName("type")]
     public string? Type { get; set; }
 
     /// <summary>
@@ -27,27 +28,31 @@ public class ProblemDetails
     /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyOrder(-4)]
+    [JsonPropertyName("title")]
     public string? Title { get; set; }
 
     /// <summary>
     /// The HTTP status code([RFC7231], Section 6) generated by the origin server for this occurrence of the problem.
     /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyOrder(-3)]
+    [JsonPropertyName("status")]
     public int? Status { get; set; }
 
     /// <summary>
     /// A human-readable explanation specific to this occurrence of the problem.
     /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyOrder(-2)]
+    [JsonPropertyName("detail")]
     public string? Detail { get; set; }
 
     /// <summary>
     /// A URI reference that identifies the specific occurrence of the problem. It may or may not yield further information if dereferenced.
     /// </summary>
     [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
     [JsonPropertyOrder(-1)]
+    [JsonPropertyName("instance")]
     public string? Instance { get; set; }
 
     /// <summary>

src/Http/Http.Extensions/test/ProblemDetailsDefaultWriterTest.cs

@@ -54,6 +54,68 @@ public async Task WriteAsync_Works()
         Assert.Equal(expectedProblem.Instance, problemDetails.Instance);
     }
 
+    [Fact]
+    public async Task WriteAsync_Works_ProperCasing()
+    {
+        // Arrange
+        var writer = GetWriter();
+        var stream = new MemoryStream();
+        var context = CreateContext(stream);
+        var expectedProblem = new ProblemDetails()
+        {
+            Detail = "Custom Bad Request",
+            Instance = "Custom Bad Request",
+            Status = StatusCodes.Status400BadRequest,
+            Type = "https://tools.ietf.org/html/rfc9110#section-15.5.1-custom",
+            Title = "Custom Bad Request",
+            Extensions = new Dictionary<string, object>() { { "extensionKey", 1 } }
+        };
+        var problemDetailsContext = new ProblemDetailsContext()
+        {
+            HttpContext = context,
+            ProblemDetails = expectedProblem
+        };
+
+        //Act
+        await writer.WriteAsync(problemDetailsContext);
+
+        //Assert
+        stream.Position = 0;
+        var result = await JsonSerializer.DeserializeAsync<Dictionary<string, object>>(stream, JsonSerializerOptions.Default);
+        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "extensionKey", 5 } }));
+    }
+
+    [Fact]
+    public async Task WriteAsync_Works_ProperCasing_ValidationProblemDetails()
+    {
+        // Arrange
+        var writer = GetWriter();
+        var stream = new MemoryStream();
+        var context = CreateContext(stream);
+        var expectedProblem = new ValidationProblemDetails()
+        {
+            Detail = "Custom Bad Request",
+            Instance = "Custom Bad Request",
+            Status = StatusCodes.Status400BadRequest,
+            Type = "https://tools.ietf.org/html/rfc9110#section-15.5.1-custom",
+            Title = "Custom Bad Request",
+            Errors = new Dictionary<string, string[]>() { { "name", ["Name is invalid."] } }
+        };
+        var problemDetailsContext = new ProblemDetailsContext()
+        {
+            HttpContext = context,
+            ProblemDetails = expectedProblem
+        };
+
+        //Act
+        await writer.WriteAsync(problemDetailsContext);
+
+        //Assert
+        stream.Position = 0;
+        var result = await JsonSerializer.DeserializeAsync<Dictionary<string, object>>(stream, JsonSerializerOptions.Default);
+        Assert.Equal(result.Keys, new(new() { { "type", 0 }, { "title", 1 }, { "status", 2 }, { "detail", 3 }, { "instance", 4 }, { "errors", 5 } }));
+    }
+
     [Fact]
     public async Task WriteAsync_Works_WhenReplacingProblemDetailsUsingSetter()
     {

src/Mvc/Mvc.Core/src/ValidationProblemDetails.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Text.Json.Serialization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Core;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
@@ -81,5 +82,6 @@ public ValidationProblemDetails(IDictionary<string, string[]> errors)
     /// <summary>
     /// Gets the validation errors associated with this instance of <see cref="HttpValidationProblemDetails"/>.
     /// </summary>
+    [JsonPropertyName("errors")]
     public new IDictionary<string, string[]> Errors { get { return base.Errors; } set { base.Errors = value; } }
 }