rubocop-hq/rubocop

# frozen_string_literal: true

module RuboCop
  module Cop
    module Lint
      # Checks that there are no repeated exceptions
      # used in 'rescue' expressions.
      #
      # @example
      #   # bad
      #   begin
      #     something
      #   rescue FirstException
      #     handle_exception
      #   rescue FirstException
      #     handle_other_exception
      #   end
      #
      #   # good
      #   begin
      #     something
      #   rescue FirstException
      #     handle_exception
      #   rescue SecondException
      #     handle_other_exception
      #   end
      #
      class DuplicateRescueException < Base
        include RescueNode

        MSG = 'Duplicate `rescue` exception detected.'

        def on_rescue(node)
          return if rescue_modifier?(node)

          node.resbody_branches.each_with_object(Set.new) do |resbody, previous|
            rescued_exceptions = resbody.exceptions

            rescued_exceptions.each do |exception|
              add_offense(exception) unless previous.add?(exception)
            end
          end
        end
      end
    end
  end
end