1 files changed, 43 insertions, 0 deletions
diff --git a/rubocop/cop/static_translation_definition.rb b/rubocop/cop/static_translation_definition.rb
new file mode 100644
index 00000000000..736d8767342
--- /dev/null
+++ b/rubocop/cop/static_translation_definition.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    class StaticTranslationDefinition < RuboCop::Cop::Cop
+      MSG = "The text you're translating will be already in the translated form when it's assigned to the constant. When a users changes the locale, these texts won't be translated again. Consider moving the translation logic to a method.".freeze
+
+      TRANSLATION_METHODS = %i[_ s_ n_].freeze
+
+      def_node_matcher :translation_method?, <<~PATTERN
+      (send _ _ str*)
+      PATTERN
+
+      def_node_matcher :lambda_node?, <<~PATTERN
+      (send _ :lambda)
+      PATTERN
+
+      def on_send(node)
+        return unless translation_method?(node)
+
+        method_name = node.children[1]
+        return unless TRANSLATION_METHODS.include?(method_name)
+
+        node.each_ancestor do |ancestor|
+          receiver, _ = *ancestor
+          break if lambda_node?(receiver) # translations defined in lambda nodes should be allowed
+
+          if constant_assignment?(ancestor)
+            add_offense(node, location: :expression)
+
+            break
+          end
+        end
+      end
+
+      private
+
+      def constant_assignment?(node)
+        node.type == :casgn
+      end
+    end
+  end
+end