1 files changed, 46 insertions, 0 deletions
diff --git a/rubocop/cop/graphql/resolver_type.rb b/rubocop/cop/graphql/resolver_type.rb
new file mode 100644
index 00000000000..1209c5dbc6b
--- /dev/null
+++ b/rubocop/cop/graphql/resolver_type.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+# This cop checks for missing GraphQL type annotations on resolvers
+#
+# @example
+#
+#   # bad
+#   module Resolvers
+#     class NoTypeResolver < BaseResolver
+#       field :some_field, GraphQL::STRING_TYPE
+#     end
+#   end
+#
+#   # good
+#   module Resolvers
+#     class WithTypeResolver < BaseResolver
+#       type MyType, null: true
+#
+#       field :some_field, GraphQL::STRING_TYPE
+#     end
+#   end
+
+module RuboCop
+  module Cop
+    module Graphql
+      class ResolverType < RuboCop::Cop::Cop
+        MSG = 'Missing type annotation: Please add `type` DSL method call. ' \
+          'e.g: type UserType.connection_type, null: true'
+
+        def_node_matcher :typed?, <<~PATTERN
+          (... (begin <(send nil? :type ...) ...>))
+        PATTERN
+
+        def on_class(node)
+          add_offense(node, location: :expression) if resolver?(node) && !typed?(node)
+        end
+
+        private
+
+        def resolver?(node)
+          node.loc.name.source.end_with?('Resolver')
+        end
+      end
+    end
+  end
+end