fix: parse +json response content types

Author: f440

README.md

@@ -167,7 +167,7 @@ This piece of middleware validates the contents of the response received from up
 |raise| false | false | Raise an exception on error instead of responding with a generic error body. |
 |validate_success_only| true | false | Also validate non-2xx responses only. |
 |ignore_error| false | false | Validate and ignore result even if validation is error. So always return original data. |
-|parse_response_by_content_type| true | true | Parse response body to JSON only if Content-Type header is 'application/json'. When false, this always optimistically parses as JSON without checking for Content-Type header. |
+|parse_response_by_content_type| true | true | Parse response body to JSON only if Content-Type header is `application/json` or an `application/*+json` media type such as `application/problem+json`. When false, this always optimistically parses as JSON without checking for Content-Type header. |
 |strict| false | false | Puts the middleware into strict mode, meaning that response code and content type does not defined in the schema will be responded to with a 500 instead of application's status code. |
 |strict_reference_validation| always false | false | Raises an exception (`OpenAPIParser::MissingReferenceError`) on middleware load if the provided schema file contains unresolvable references (`$ref:"#/something/not/here"`). Not supported on Hyper-schema parser. Defaults to `false` on OpenAPI3 but will default to `true` in next major version. |
 

lib/committee/schema_validator.rb

@@ -2,11 +2,18 @@
 
 module Committee
   module SchemaValidator
+    JSON_MEDIA_TYPE_PATTERN = %r{\Aapplication/(?:.+\+)?json\z}.freeze
+
     class << self
       def request_media_type(request)
         Rack::MediaType.type(request.env['CONTENT_TYPE'])
       end
 
+      def json_media_type?(content_type)
+        normalized_content_type = Rack::MediaType.type(content_type)
+        normalized_content_type&.match?(JSON_MEDIA_TYPE_PATTERN) || false
+      end
+
       # @param [String] prefix
       # @return [Regexp]
       def build_prefix_regexp(prefix)

lib/committee/schema_validator/hyper_schema.rb

@@ -31,7 +31,7 @@ def response_validate(status, headers, response, _test_method = false, custom_bo
         elsif !full_body.empty?
           parse_to_json = if validator_option.parse_response_by_content_type
                             content_type_key = headers.keys.detect { |k| k.casecmp?('Content-Type') }
-            headers.fetch(content_type_key, nil)&.start_with?('application/json')
+                            Committee::SchemaValidator.json_media_type?(headers.fetch(content_type_key, nil))
           else
             true
           end

lib/committee/schema_validator/open_api_3.rb

@@ -28,7 +28,7 @@ def response_validate(status, headers, response, test_method = false, custom_bod
 
         parse_to_json = if validator_option.parse_response_by_content_type
                           content_type_key = headers.keys.detect { |k| k.casecmp?('Content-Type') }
-                          headers.fetch(content_type_key, nil)&.start_with?('application/json')
+                          Committee::SchemaValidator.json_media_type?(headers.fetch(content_type_key, nil))
                         else
                           true
                         end

test/middleware/response_validation_open_api_3_test.rb

@@ -33,6 +33,18 @@ def app
     assert_equal 200, last_response.status
   end
 
+  it "passes through a valid response with a +json content-type" do
+    @app = new_response_rack(
+      JSON.generate(CHARACTERS_RESPONSE),
+      { "Content-Type" => "application/problem+json; charset=utf-8" },
+      schema: open_api_3_schema,
+      parse_response_by_content_type: true,
+    )
+
+    get "/characters"
+    assert_equal 200, last_response.status
+  end
+
   it "passes through a invalid json" do
     @app = new_response_rack("not_json", {}, schema: open_api_3_schema)
 

test/schema_validator_test.rb

@@ -21,6 +21,39 @@
     assert_equal 'multipart/form-data', media_type
   end
 
+  it "detects application/json as a JSON media type" do
+    assert_equal true, Committee::SchemaValidator.json_media_type?("application/json")
+  end
+
+  it "detects application/problem+json with parameters as a JSON media type" do
+    assert_equal true, Committee::SchemaValidator.json_media_type?("application/problem+json; charset=utf-8")
+  end
+
+  it "detects application/vnd.api+json as a JSON media type" do
+    assert_equal true, Committee::SchemaValidator.json_media_type?("application/vnd.api+json")
+  end
+
+  it "does not detect application/x-ndjson as a JSON media type" do
+    assert_equal false, Committee::SchemaValidator.json_media_type?("application/x-ndjson")
+  end
+
+  it "does not detect non-JSON content types as JSON media types" do
+    assert_equal false, Committee::SchemaValidator.json_media_type?("test/csv")
+    assert_equal false, Committee::SchemaValidator.json_media_type?(nil)
+  end
+
+  it "parses +json responses in the HyperSchema validator" do
+    schema = Committee::Drivers::OpenAPI2::Driver.new.parse(open_api_2_data)
+    validator_option = Committee::SchemaValidator::Option.new({ parse_response_by_content_type: true }, schema, :hyper_schema)
+    router = Committee::SchemaValidator::HyperSchema::Router.new(schema, validator_option)
+    request = Rack::Request.new({ "REQUEST_METHOD" => "GET", "PATH_INFO" => "/api/pets", "rack.input" => StringIO.new("") })
+    validator = Committee::SchemaValidator::HyperSchema.new(router, request, validator_option)
+
+    validator.link.media_type = "application/vnd.api+json"
+
+    validator.response_validate(200, { "Content-Type" => "application/vnd.api+json" }, [JSON.generate([ValidPet])])
+  end
+
   it "builds prefix regexp with a path segment boundary" do
     regexp = Committee::SchemaValidator.build_prefix_regexp("/v1")