lib/rubocop/cop/style/redundant_exception.rb
# frozen_string_literal: true
module RuboCop
module Cop
module Style
# Checks for RuntimeError as the argument of raise/fail.
#
# @example
# # bad
# raise RuntimeError, 'message'
# raise RuntimeError.new('message')
#
# # good
# raise 'message'
#
# # bad - message is not a string
# raise RuntimeError, Object.new
# raise RuntimeError.new(Object.new)
#
# # good
# raise Object.new.to_s
#
class RedundantException < Base
extend AutoCorrector
MSG_1 = 'Redundant `RuntimeError` argument can be removed.'
MSG_2 = 'Redundant `RuntimeError.new` call can be replaced with just the message.'
RESTRICT_ON_SEND = %i[raise fail].freeze
# Switch `raise RuntimeError, 'message'` to `raise 'message'`, and
# `raise RuntimeError.new('message')` to `raise 'message'`.
def on_send(node)
fix_exploded(node) || fix_compact(node)
end
private
def fix_exploded(node)
exploded?(node) do |command, message|
add_offense(node, message: MSG_1) do |corrector|
corrector.replace(node, replaced_exploded(node, command, message))
end
end
end
def replaced_exploded(node, command, message)
arg = string_message?(message) ? message.source : "#{message.source}.to_s"
arg = node.parenthesized? ? "(#{arg})" : " #{arg}"
"#{command}#{arg}"
end
def string_message?(message)
message.str_type? || message.dstr_type? || message.xstr_type?
end
def fix_compact(node)
compact?(node) do |new_call, message|
add_offense(node, message: MSG_2) do |corrector|
corrector.replace(new_call, replaced_compact(message))
end
end
end
def replaced_compact(message)
if string_message?(message)
message.source
else
"#{message.source}.to_s"
end
end
# @!method exploded?(node)
def_node_matcher :exploded?, <<~PATTERN
(send nil? ${:raise :fail} (const {nil? cbase} :RuntimeError) $_)
PATTERN
# @!method compact?(node)
def_node_matcher :compact?, <<~PATTERN
(send nil? {:raise :fail} $(send (const {nil? cbase} :RuntimeError) :new $_))
PATTERN
end
end
end
end