Also require at least one argument for input objects

Author: rmosolgo

lib/graphql/schema/validation.rb

@@ -106,6 +106,7 @@ def self.assert_named_items_are_valid(item_name, get_items_proc)
 
         HAS_AT_LEAST_ONE_FIELD = Rules.count_at_least("field", 1, ->(type) { type.all_fields })
         FIELDS_ARE_VALID = Rules.assert_named_items_are_valid("field", ->(type) { type.all_fields })
+        HAS_AT_LEAST_ONE_ARGUMENT = Rules.count_at_least("argument", 1, ->(type) { type.arguments })
 
         HAS_ONE_OR_MORE_POSSIBLE_TYPES = ->(type) {
           type.possible_types.length >= 1 ? nil : "must have at least one possible type"
@@ -279,6 +280,7 @@ def self.assert_named_items_are_valid(item_name, get_items_proc)
           Rules::INTERFACES_ARE_IMPLEMENTED,
         ],
         GraphQL::InputObjectType => [
+          Rules::HAS_AT_LEAST_ONE_ARGUMENT,
           Rules::ARGUMENTS_ARE_STRING_TO_ARGUMENT,
           Rules::ARGUMENTS_ARE_VALID,
         ],

spec/graphql/schema/validation_spec.rb

@@ -276,13 +276,22 @@ def assert_validation_warns(object, warning)
       end
     }
 
+    let(:no_arguments_input) {
+      GraphQL::InputObjectType.define do
+        name "NoArguments"
+      end
+    }
     it "requires {String => Argument} arguments" do
       assert_error_includes invalid_arguments_input, "map String => GraphQL::Argument, not #{integer_class_name} => Symbol"
     end
 
     it "applies validation to its member Arguments" do
       assert_error_includes invalid_argument_member_input, "default value [\"xyz\"] is not valid for type Float"
     end
+
+    it "requires one argument" do
+      assert_error_includes no_arguments_input, "must define at least 1 argument"
+    end
   end
 
   describe "validating InterfaceTypes" do