Make extension regex configurable

This has been provided so that the OpenAPI 3.1 Schema can accept a
schema with extensions without the `x-` prefix that OpenAPI nodes
require.

Author: kevindew

lib/openapi3_parser/node_factory/object.rb

@@ -11,7 +11,7 @@ class Object
 
       def_delegators "self.class",
                      :field_configs,
-                     :allowed_extensions?,
+                     :extension_regex,
                      :mutually_exclusive_fields,
                      :allowed_default?,
                      :validations

lib/openapi3_parser/node_factory/object_factory/dsl.rb

@@ -17,16 +17,12 @@ def field_configs
           @field_configs ||= {}
         end
 
-        def allow_extensions
-          @allow_extensions = true
+        def allow_extensions(regex: EXTENSION_REGEX)
+          @extension_regex = regex
         end
 
-        def allowed_extensions?
-          if instance_variable_defined?(:@allow_extensions)
-            @allow_extensions == true
-          else
-            false
-          end
+        def extension_regex
+          @extension_regex ||= nil
         end
 
         def mutually_exclusive(*fields, required: false)

lib/openapi3_parser/node_factory/object_factory/validator.rb

@@ -41,7 +41,7 @@ def check_required_fields
         def check_unexpected_fields
           Validators::UnexpectedFields.call(
             validatable,
-            allow_extensions: factory.allowed_extensions?,
+            extension_regex: factory.extension_regex,
             allowed_fields: factory.allowed_fields,
             raise_on_invalid: raise_on_invalid
           )

lib/openapi3_parser/node_factory/schema/oas_dialect_3_1.rb

@@ -6,6 +6,9 @@ module Openapi3Parser
   module NodeFactory
     module Schema
       class OasDialect3_1 < NodeFactory::Object # rubocop:disable Naming/ClassAndModuleCamelCase
+        # Allows any extension as per:
+        # https://github.com/OAI/OpenAPI-Specification/blob/a1facce1b3621df3630cb692e9fbe18a7612ea6d/versions/3.1.0.md#fixed-fields-20
+        allow_extensions(regex: /.*/)
       end
     end
   end

lib/openapi3_parser/validators/unexpected_fields.rb

@@ -14,11 +14,11 @@ def self.call(*args, **kwargs)
 
       def call(validatable,
                allowed_fields:,
-               allow_extensions: true,
+               extension_regex: nil,
                raise_on_invalid: true)
         fields = unexpected_fields(validatable.input,
                                    allowed_fields,
-                                   allow_extensions)
+                                   extension_regex)
         return if fields.empty?
 
         if raise_on_invalid
@@ -35,11 +35,11 @@ def call(validatable,
 
       private
 
-      def unexpected_fields(input, allowed_fields, allow_extensions)
+      def unexpected_fields(input, allowed_fields, extension_regex)
         extra_keys = input.keys - allowed_fields
-        return extra_keys unless allow_extensions
+        return extra_keys unless extension_regex
 
-        extra_keys.grep_v(NodeFactory::EXTENSION_REGEX)
+        extra_keys.grep_v(extension_regex)
       end
     end
   end

spec/integration/open_v3.1_examples_spec.rb

@@ -12,7 +12,7 @@
   context "when using the webhook example" do
     let(:path) { File.join(__dir__, "..", "support", "examples", "v3.1", "webhook-example.yaml") }
 
-    xit "is a valid document" do
+    it "is a valid document" do
       expect(document).to be_valid
     end
 

spec/lib/openapi3_parser/validators/unexpected_fields_spec.rb

@@ -27,23 +27,22 @@
       end
     end
 
-    describe "allow_extensions option" do
+    describe "extension_regex option" do
       let(:validatable) do
         create_validatable({ "x-extension" => "my extension",
                              "x-extension-2" => "my other extension" })
       end
 
-      it "defaults to allowing extensions" do
+      it "defaults to disallowing extensions" do
+        validatable = create_validatable({ "extension" => "my extension" })
         expect { described_class.call(validatable, allowed_fields: []) }
-          .not_to raise_error
+          .to raise_error(Openapi3Parser::Error::UnexpectedFields, "Unexpected fields for #/: extension")
       end
 
-      it "raises an error when allow_extensions is false" do
-        expect { described_class.call(validatable, allowed_fields: [], allow_extensions: false) }
-          .to raise_error(
-            Openapi3Parser::Error::UnexpectedFields,
-            "Unexpected fields for #/: x-extension and x-extension-2"
-          )
+      it "accepts a regex of the pattern of extension that will be accepted" do
+        validatable = create_validatable({ "x-extension" => "my extension" })
+        expect { described_class.call(validatable, allowed_fields: [], extension_regex: /^x-.*/) }
+          .not_to raise_error
       end
     end