Add support for extend scalar to parser

Author: cjoudrey

lib/graphql/compatibility/schema_parser_specification.rb

@@ -246,6 +246,23 @@ def test_it_parses_schema_extensions_with_only_directives
             assert_equal nil, schema_extension.subscription
           end
 
+          def test_it_parses_scalar_extensions
+            document = parse('
+              extend scalar Date @something @somethingElse
+            ')
+
+            scalar_extension = document.definitions.first
+            assert_equal GraphQL::Language::Nodes::ScalarTypeExtension, scalar_extension.class
+            assert_equal 'Date', scalar_extension.name
+            assert_equal [2, 15], scalar_extension.position
+
+            assert_equal 2, scalar_extension.directives.length
+            assert_equal GraphQL::Language::Nodes::Directive, scalar_extension.directives.first.class
+            assert_equal 'something', scalar_extension.directives.first.name
+            assert_equal GraphQL::Language::Nodes::Directive, scalar_extension.directives.last.class
+            assert_equal 'somethingElse', scalar_extension.directives.last.name
+          end
+
           def test_it_parses_whole_definition_with_descriptions
             document = parse(SCHEMA_DEFINITION_STRING)
 

lib/graphql/language/nodes.rb

@@ -418,6 +418,16 @@ def initialize_node(name:, directives: [], description: nil)
         end
       end
 
+      class ScalarTypeExtension < AbstractNode
+        attr_accessor :name, :directives
+        alias :children :directives
+
+        def initialize_node(name:, directives:)
+          @name = name
+          @directives = directives
+        end
+      end
+
       class ObjectTypeDefinition < AbstractNode
         include Scalars::Name
 

lib/graphql/language/parser.y

@@ -299,11 +299,17 @@ rule
 
   type_system_extension:
       schema_extension
+    | type_extension
 
   schema_extension:
       EXTEND SCHEMA directives_list_opt LCURLY operation_type_definition_list RCURLY { return make_node(:SchemaExtension, position_source: val[0], directives: val[2], **val[4]) }
     | EXTEND SCHEMA directives_list { return make_node(:SchemaExtension, position_source: val[0], directives: val[2]) }
 
+  type_extension:
+      scalar_type_extension
+
+  scalar_type_extension: EXTEND SCALAR name directives_list { return make_node(:ScalarTypeExtension, name: val[2], directives: val[3], position_source: val[0]) }
+
   scalar_type_definition: SCALAR name directives_list_opt { return make_node(:ScalarTypeDefinition, name: val[1], directives: val[2], description: get_description(val[0]), position_source: val[0]) }
 
   object_type_definition: