1 files changed, 58 insertions, 0 deletions
diff --git a/rubocop/cop/migration/background_migration_missing_active_concern.rb b/rubocop/cop/migration/background_migration_missing_active_concern.rb
new file mode 100644
index 00000000000..417472bf512
--- /dev/null
+++ b/rubocop/cop/migration/background_migration_missing_active_concern.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks `ActiveSupport::Concern` is included in EE batched background migrations
+      # if they define `scope_to`.
+      class BackgroundMigrationMissingActiveConcern < RuboCop::Cop::Base
+        include MigrationHelpers
+
+        MSG = <<~MSG
+          Extend `ActiveSupport::Concern` in the EE background migration if it defines `scope_to`.
+        MSG
+
+        def_node_matcher :prepended_block_uses_scope_to?, <<~PATTERN
+          (:block (:send nil? :prepended) (:args) `(:send nil? :scope_to ...))
+        PATTERN
+
+        def_node_matcher :scope_to?, <<~PATTERN
+          (:send nil? :scope_to ...)
+        PATTERN
+
+        def_node_matcher :extend_activesupport_concern?, <<~PATTERN
+          (:send nil? :extend (:const (:const nil? :ActiveSupport) :Concern))
+        PATTERN
+
+        def on_block(node)
+          return unless in_ee_background_migration?(node)
+          return unless prepended_block_uses_scope_to?(node)
+
+          return if module_extends_activesupport_concern?(node)
+
+          node.descendants.each do |descendant|
+            next unless scope_to?(descendant)
+
+            add_offense(descendant)
+          end
+        end
+
+        private
+
+        def module_extends_activesupport_concern?(node)
+          while node = node.parent
+            break if node.type == :module
+          end
+
+          return false unless node
+
+          node.descendants.any? do |descendant|
+            extend_activesupport_concern?(descendant)
+          end
+        end
+      end
+    end
+  end
+end