Fix default behavior for 401/403 http response codes (#429)

* Fix default behavior for 401/403 http response codes

* Add Accept and Accept-Charset headers

* fix default user agent version

* add note

src/GraphQL.Client/GraphQLHttpClientOptions.cs

@@ -52,8 +52,12 @@ public class GraphQLHttpClientOptions
 
     /// <summary>
     /// Delegate to determine if GraphQL response may be properly deserialized into <see cref="GraphQLResponse{T}"/>.
+    /// Note that compatible to the draft graphql-over-http spec GraphQL Server MAY return 4xx status codes (401/403, etc.)
+    /// with well-formed GraphQL response containing errors collection.
     /// </summary>
-    public Func<HttpResponseMessage, bool> IsValidResponseToDeserialize { get; set; } = r => r.IsSuccessStatusCode || r.StatusCode == HttpStatusCode.BadRequest;
+    public Func<HttpResponseMessage, bool> IsValidResponseToDeserialize { get; set; } = r =>
+        // Why not application/json? See https://github.com/graphql/graphql-over-http/blob/main/spec/GraphQLOverHTTP.md#processing-the-response
+        r.IsSuccessStatusCode || r.StatusCode == HttpStatusCode.BadRequest || r.Content.Headers.ContentType.MediaType == "application/graphql+json";
 
     /// <summary>
     /// This callback is called after successfully establishing a websocket connection but before any regular request is made.

src/GraphQL.Client/GraphQLHttpRequest.cs

@@ -1,3 +1,4 @@
+using System.Net.Http.Headers;
 using System.Runtime.Serialization;
 using System.Text;
 using GraphQL.Client.Abstractions;
@@ -38,6 +39,9 @@ public virtual HttpRequestMessage ToHttpRequestMessage(GraphQLHttpClientOptions
         {
             Content = new StringContent(serializer.SerializeToString(this), Encoding.UTF8, options.MediaType)
         };
+        message.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/graphql+json"));
+        message.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+        message.Headers.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
 
 #pragma warning disable CS0618 // Type or member is obsolete
         PreprocessHttpRequestMessage(message);

tests/GraphQL.Integration.Tests/QueryAndMutationTests/Base.cs

@@ -1,4 +1,5 @@
 using System.Net;
+using System.Net.Http.Headers;
 using FluentAssertions;
 using GraphQL.Client.Abstractions;
 using GraphQL.Client.Http;
@@ -173,9 +174,13 @@ public async void PreprocessHttpRequestMessageIsCalled()
 #pragma warning restore CS0618 // Type or member is obsolete
         };
 
-        var defaultHeaders = StarWarsClient.HttpClient.DefaultRequestHeaders;
+        var expectedHeaders = new HttpRequestMessage().Headers;
+        expectedHeaders.UserAgent.Add(new ProductInfoHeaderValue("GraphQL.Client", typeof(GraphQLHttpClient).Assembly.GetName().Version.ToString()));
+        expectedHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/graphql+json"));
+        expectedHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+        expectedHeaders.AcceptCharset.Add(new StringWithQualityHeaderValue("utf-8"));
         var response = await StarWarsClient.SendQueryAsync(graphQLRequest, () => new { Human = new { Name = string.Empty } });
-        callbackTester.Should().HaveBeenInvokedWithPayload().Which.Headers.Should().BeEquivalentTo(defaultHeaders);
+        callbackTester.Should().HaveBeenInvokedWithPayload().Which.Headers.Should().BeEquivalentTo(expectedHeaders);
         Assert.Null(response.Errors);
         Assert.Equal("Luke", response.Data.Human.Name);
     }