require_relative '../../migration_helpers' module RuboCop module Cop module Migration # This cop requires a default value and disallows nulls for boolean # columns on small tables. # # In general, this prevents 3-state-booleans. # https://robots.thoughtbot.com/avoid-the-threestate-boolean-problem # # In particular, for the `application_settings` table, this ensures that # upgraded installations get a proper default for the new boolean setting. # A developer might otherwise mistakenly assume that a value in # `ApplicationSetting.defaults` is sufficient. # # See https://gitlab.com/gitlab-org/gitlab/issues/2750 for more # information. class SaferBooleanColumn < RuboCop::Cop::Cop include MigrationHelpers DEFAULT_OFFENSE = 'Boolean columns on the `%s` table should have a default. You may wish to use `add_column_with_default`.'.freeze NULL_OFFENSE = 'Boolean columns on the `%s` table should disallow nulls.'.freeze DEFAULT_AND_NULL_OFFENSE = 'Boolean columns on the `%s` table should have a default and should disallow nulls. You may wish to use `add_column_with_default`.'.freeze SMALL_TABLES = %i[ application_settings ].freeze def_node_matcher :add_column?, <<~PATTERN (send nil? :add_column $...) PATTERN def on_send(node) return unless in_migration?(node) matched = add_column?(node) return unless matched table, _, type = matched.to_a.take(3).map(&:children).map(&:first) opts = matched[3] return unless SMALL_TABLES.include?(table) && type == :boolean no_default = no_default?(opts) nulls_allowed = nulls_allowed?(opts) offense = if no_default && nulls_allowed DEFAULT_AND_NULL_OFFENSE elsif no_default DEFAULT_OFFENSE elsif nulls_allowed NULL_OFFENSE end add_offense(node, location: :expression, message: format(offense, table)) if offense end def no_default?(opts) return true unless opts each_hash_node_pair(opts) do |key, value| break value == 'nil' if key == :default end end def nulls_allowed?(opts) return true unless opts each_hash_node_pair(opts) do |key, value| break value != 'false' if key == :null end end def each_hash_node_pair(hash_node, &block) hash_node.each_node(:pair) do |pair| key = hash_pair_key(pair) value = hash_pair_value(pair) yield(key, value) end end def hash_pair_key(pair) pair.children[0].children[0] end def hash_pair_value(pair) pair.children[1].source end end end end end