1 files changed, 52 insertions, 0 deletions
diff --git a/rubocop/cop/migration/drop_table.rb b/rubocop/cop/migration/drop_table.rb
new file mode 100644
index 00000000000..2a0f57c0c13
--- /dev/null
+++ b/rubocop/cop/migration/drop_table.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require_relative '../../migration_helpers'
+
+module RuboCop
+  module Cop
+    module Migration
+      # Cop that checks if `drop_table` is called in deployment migrations.
+      # Calling it in deployment migrations can cause downtimes as there still may be code using the target tables.
+      class DropTable < RuboCop::Cop::Cop
+        include MigrationHelpers
+
+        MSG = <<-MESSAGE.delete("\n").squeeze
+          `drop_table` in deployment migrations requires downtime.
+          Drop tables in post-deployment migrations instead.
+        MESSAGE
+
+        def on_def(node)
+          return unless in_deployment_migration?(node)
+
+          node.each_descendant(:send) do |send_node|
+            next unless offensible?(send_node)
+
+            add_offense(send_node, location: :selector)
+          end
+        end
+
+        private
+
+        def offensible?(node)
+          drop_table?(node) || drop_table_in_execute?(node)
+        end
+
+        def drop_table?(node)
+          node.children[1] == :drop_table
+        end
+
+        def drop_table_in_execute?(node)
+          execute?(node) && drop_table_in_execute_sql?(node)
+        end
+
+        def execute?(node)
+          node.children[1] == :execute
+        end
+
+        def drop_table_in_execute_sql?(node)
+          node.children[2].to_s.match?(/drop\s+table/i)
+        end
+      end
+    end
+  end
+end