fix(content-negotiation): correct 406 and 415 error mapping (#418)

Map invalid Content-Type requests to UnsupportedMediaType (415) and invalid Accept requests to UnacceptableMediaType (406). Update the spec compliance tests to assert the corrected statuses and JSON:API error codes/titles.

Author: vkryukov

lib/ash_json_api/error/unacceptable_media_type.ex

@@ -4,7 +4,8 @@
 
 defmodule AshJsonApi.Error.UnacceptableMediaType do
   @moduledoc """
-  Returned when the client does not provide (via the `Content-Type` header) the correct json API media type: application/vnd.api+json
+  Returned when the client does not accept (via the `Accept` header) the JSON:API
+  media type: application/vnd.api+json
   """
   use Splode.Error, class: :invalid
 

lib/ash_json_api/error/unsupported_media_type.ex

@@ -4,7 +4,8 @@
 
 defmodule AshJsonApi.Error.UnsupportedMediaType do
   @moduledoc """
-  Returned when the client does not accept (via the `Accept` header) the json API media type: application/vnd.api+json
+  Returned when the client does not provide (via the `Content-Type` header) the
+  correct JSON:API media type: application/vnd.api+json
   """
   use Splode.Error, class: :invalid
 

lib/ash_json_api/request.ex

@@ -277,7 +277,7 @@ defmodule AshJsonApi.Request do
         if any_content_type_supported? || json_api_content_type_supported? do
           request
         else
-          add_error(request, UnacceptableMediaType.exception([]), request.route.type)
+          add_error(request, UnsupportedMediaType.exception([]), request.route.type)
         end
     end
   end
@@ -314,7 +314,7 @@ defmodule AshJsonApi.Request do
     if accepts_json_api? do
       request
     else
-      add_error(request, UnsupportedMediaType.exception([]), request.route.type)
+      add_error(request, UnacceptableMediaType.exception([]), request.route.type)
     end
   end
 

test/spec_compliance/content_negotiation_test.exs

@@ -204,11 +204,16 @@ defmodule AshJsonApi.ContentNegotiationTest do
 
     @tag capture_log: true
     test "request Content-Type header includes two instances of JSON:API modified with a param" do
-      post(Domain, "/posts", @create_body,
+      Domain
+      |> post("/posts", @create_body,
         req_content_type_header:
           "application/vnd.api+json; charset=test, application/vnd.api+json; charset=test",
-        status: 406
+        status: 415
       )
+      |> assert_has_error(%{
+        "code" => "unsupported_media_type",
+        "title" => "Unsupported Media Type"
+      })
     end
 
     test "request Content-Type header is a random value" do
@@ -219,10 +224,15 @@ defmodule AshJsonApi.ContentNegotiationTest do
 
     @tag capture_log: true
     test "request Content-Type header is a valid media type other than JSON:API" do
-      post(Domain, "/posts", @create_body,
+      Domain
+      |> post("/posts", @create_body,
         req_content_type_header: "application/vnd.api+json; charset=\"utf-8\"",
-        status: 406
+        status: 415
       )
+      |> assert_has_error(%{
+        "code" => "unsupported_media_type",
+        "title" => "Unsupported Media Type"
+      })
     end
   end
 
@@ -269,11 +279,16 @@ defmodule AshJsonApi.ContentNegotiationTest do
     test "request Accept header includes two instances of JSON:API modified with a param", %{
       post: post
     } do
-      get(Domain, "/posts/#{post.id}",
+      Domain
+      |> get("/posts/#{post.id}",
         req_accept_header:
           "application/vnd.api+json; charset=test, application/vnd.api+json; charset=test",
-        status: 415
+        status: 406
       )
+      |> assert_has_error(%{
+        "code" => "unacceptable_media_type",
+        "title" => "Unacceptable Media Type"
+      })
     end
 
     test "request Accept header is a random value", %{post: post} do
@@ -290,10 +305,15 @@ defmodule AshJsonApi.ContentNegotiationTest do
 
     @tag capture_log: true
     test "request Accept header is a valid media type other than JSON:API", %{post: post} do
-      get(Domain, "/posts/#{post.id}",
+      Domain
+      |> get("/posts/#{post.id}",
         req_accept_header: "application/vnd.api+json; charset=\"utf-8\"",
-        status: 415
+        status: 406
       )
+      |> assert_has_error(%{
+        "code" => "unacceptable_media_type",
+        "title" => "Unacceptable Media Type"
+      })
     end
 
     test "request Accept header is a valid media type other than JSON:API with bypass config", %{