Merge pull request #3500 from rmosolgo/resolver-extension-inheritance

Inherit extensions in resolvers

Author: Robert Mosolgo

lib/graphql/schema/resolver.rb

@@ -374,16 +374,36 @@ def arguments_loads_as_type
         # @param extension [Class] Extension class
         # @param options [Hash] Optional extension options
         def extension(extension, **options)
-          extensions << {extension => options}
+          @own_extensions ||= []
+          @own_extensions << {extension => options}
         end
 
         # @api private
         def extensions
-          @extensions ||= []
+          own_exts = @own_extensions
+          # Jump through some hoops to avoid creating arrays when we don't actually need them
+          if superclass.respond_to?(:extensions)
+            s_exts = superclass.extensions
+            if own_exts
+              if s_exts.any?
+                own_exts + s_exts
+              else
+                own_exts
+              end
+            else
+              s_exts
+            end
+          else
+            own_exts || EMPTY_ARRAY
+          end
         end
 
         private
 
+        def own_extensions
+          @own_extensions
+        end
+
         def own_arguments_loads_as_type
           @own_arguments_loads_as_type ||= {}
         end

spec/graphql/schema/resolver_spec.rb

@@ -811,6 +811,20 @@ def load_input(input); end
         res = exec_query " { resolverWithExtension } "
         assert_equal "Hi, Robert!", res["data"]["resolverWithExtension"]
       end
+
+      it "inherits extensions" do
+        r1 = Class.new(GraphQL::Schema::Resolver) do
+          extension(ResolverTest::GreetingExtension)
+        end
+
+        e2 = Class.new(GraphQL::Schema::FieldExtension)
+        r2 = Class.new(r1) do
+          extension(e2)
+        end
+
+        assert_equal 1, r1.extensions.size
+        assert_equal 2, r2.extensions.size
+      end
     end
 
     describe "max_page_size" do