class RuboCop::Cop::Style::RaiseArgs

This cop checks the args passed to `fail` and `raise`. For exploded style (default), it recommends passing the exception class and message to `raise`, rather than construct an instance of the error. It will still allow passing just a message, or the construction of an error with more than one argument.

The exploded style works identically, but with the addition that it will also suggest constructing error objects when the exception is passed multiple arguments.

@example

# EnforcedStyle: exploded

# bad
raise StandardError.new("message")

# good
raise StandardError, "message"
fail "message"
raise MyCustomError.new(arg1, arg2, arg3)
raise MyKwArgError.new(key1: val1, key2: val2)

@example

# EnforcedStyle: compact

# bad
raise StandardError, "message"
raise RuntimeError, arg1, arg2, arg3

# good
raise StandardError.new("message")
raise MyCustomError.new(arg1, arg2, arg3)
fail "message"

Constants

COMPACT_MSG
EXPLODED_MSG

Public Instance Methods

on_send(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 49
def on_send(node)
  return unless node.command?(:raise) || node.command?(:fail)

  case style
  when :compact
    check_compact(node)
  when :exploded
    check_exploded(node)
  end
end

Private Instance Methods

acceptable_exploded_args?(args) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 115
def acceptable_exploded_args?(args)
  # Allow code like `raise Ex.new(arg1, arg2)`.
  return true if args.size > 1

  # Disallow zero arguments.
  return false if args.empty?

  arg = args.first

  # Allow code like `raise Ex.new(kw: arg)`.
  # Allow code like `raise Ex.new(*args)`.
  arg.hash_type? || arg.splat_type?
end
autocorrect(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 62
def autocorrect(node)
  replacement = if style == :compact
                  correction_exploded_to_compact(node)
                else
                  correction_compact_to_exploded(node)
                end

  ->(corrector) { corrector.replace(node.source_range, replacement) }
end
check_compact(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 91
def check_compact(node)
  if node.arguments.size > 1
    add_offense(node) do
      opposite_style_detected
    end
  else
    correct_style_detected
  end
end
check_exploded(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 101
def check_exploded(node)
  return correct_style_detected unless node.arguments.one?

  first_arg = node.first_argument

  return unless first_arg.send_type? && first_arg.method?(:new)

  return if acceptable_exploded_args?(first_arg.arguments)

  add_offense(node) do
    opposite_style_detected
  end
end
correction_compact_to_exploded(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 72
def correction_compact_to_exploded(node)
  exception_node, _new, message_node = *node.first_argument

  message = message_node && message_node.source

  correction = exception_node.const_name.to_s
  correction = "#{correction}, #{message}" if message

  "#{node.method_name} #{correction}"
end
correction_exploded_to_compact(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 83
def correction_exploded_to_compact(node)
  exception_node, *message_nodes = *node.arguments
  return node.source if message_nodes.size > 1

  argument = message_nodes.first.source
  "#{node.method_name} #{exception_node.const_name}.new(#{argument})"
end
message(node) click to toggle source
# File lib/rubocop/cop/style/raise_args.rb, line 129
def message(node)
  if style == :compact
    format(COMPACT_MSG, node.method_name)
  else
    format(EXPLODED_MSG, node.method_name)
  end
end