1 files changed, 33 insertions, 0 deletions
diff --git a/rubocop/cop/migration/background_migration_base_class.rb b/rubocop/cop/migration/background_migration_base_class.rb
new file mode 100644
index 00000000000..50cbe3a69c3
--- /dev/null
+++ b/rubocop/cop/migration/background_migration_base_class.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Migration
+      class BackgroundMigrationBaseClass < RuboCop::Cop::Cop
+        MSG = 'Batched background migration jobs should inherit from Gitlab::BackgroundMigration::BatchedMigrationJob'
+
+        def_node_search :top_level_module?, <<~PATTERN
+          (module (const nil? :Gitlab) (module (const nil? :BackgroundMigration) ...))
+        PATTERN
+
+        def_node_matcher :matching_parent_namespace?, <<~PATTERN
+          {nil? (const (const {cbase nil?} :Gitlab) :BackgroundMigration)}
+        PATTERN
+
+        def_node_search :inherits_batched_migration_job?, <<~PATTERN
+          (class _ (const #matching_parent_namespace? :BatchedMigrationJob) ...)
+        PATTERN
+
+        def on_module(module_node)
+          return unless top_level_module?(module_node)
+
+          top_level_class_node = module_node.each_descendant(:class).first
+
+          return if top_level_class_node.nil? || inherits_batched_migration_job?(top_level_class_node)
+
+          add_offense(top_level_class_node, location: :expression)
+        end
+      end
+    end
+  end
+end