Add static translation check on ivars

rubocop/cop/static_translation_definition.rb

@@ -21,6 +21,8 @@ module RuboCop
         method_name = node.children[1]
         return unless TRANSLATION_METHODS.include?(method_name)
 
+        translation_memoized = false
+
         node.each_ancestor do |ancestor|
           receiver, _ = *ancestor
           break if lambda_node?(receiver) # translations defined in lambda nodes should be allowed
@@ -30,6 +32,14 @@ module RuboCop
 
             break
           end
+
+          translation_memoized = true if memoization?(ancestor)
+
+          if translation_memoized && class_method_definition?(ancestor)
+            add_offense(node, location: :expression)
+
+            break
+          end
         end
       end
 
@@ -38,6 +48,14 @@ module RuboCop
       def constant_assignment?(node)
         node.type == :casgn
       end
+
+      def memoization?(node)
+        node.type == :or_asgn
+      end
+
+      def class_method_definition?(node)
+        node.type == :defs
+      end
     end
   end
 end

spec/rubocop/cop/static_translation_definition_spec.rb

@@ -38,6 +38,17 @@ RSpec.describe RuboCop::Cop::StaticTranslationDefinition, type: :rubocop do
         ['A = _("a")', '_("a")', 1],
         ['B = s_("b")', 's_("b")', 1],
         ['C = n_("c")', 'n_("c")', 1],
+        [
+          <<~CODE,
+            class MyClass
+              def self.translations
+                @cache ||= { hello: _("hello") }
+              end
+            end
+          CODE
+          '_("hello")',
+          3
+        ],
         [
           <<~CODE,
             module MyModule
@@ -78,6 +89,20 @@ RSpec.describe RuboCop::Cop::StaticTranslationDefinition, type: :rubocop do
         'CONSTANT_1 = __("a")',
         'CONSTANT_2 = s__("a")',
         'CONSTANT_3 = n__("a")',
+        <<~CODE,
+          class MyClass
+            def self.method
+              @cache ||= { hello: -> { _("hello") } }
+            end
+          end
+        CODE
+        <<~CODE,
+          class MyClass
+            def method
+              @cache ||= { hello: _("hello") }
+            end
+          end
+        CODE
         <<~CODE,
           def method
             s_('a')