Custom RuboCop to search for configurable URLs?

Question

I'm writing a custom RuboCop plugin to enforce specific URLs in a Berksfile. I might have taken on more than my limited Ruby knowledge will support at this time.

Here is some pseduo code. Am I even close?

config/default.yml:

ACME/ApprovedSupermarkets:
  Description: 'Enforce the use of only authorized Chef Supermarkets.'
  Enabled: true
  Include:
    - '**/Berksfile'
  Severity: error
  Sources:
    - 'https://supermarket.acme.com'
    - 'https://supermarket.trusted.com'

lib/rubocop/cop/acme/approved_supermarkets.rb

# encoding: utf-8
# frozen_string_literal: true

require 'uri'

module RuboCop
  module Cop
    module ACME
      # This cop checks that only allowed supermarkets are used within Berksfiles.
      class ApprovedSupermarkets < Cop

        MSG = 'Only the use of authorized Chef Supermarkets are allowed.'.freeze

        def investigate(processed_source)
          processed_source.lines.each_with_index do |line, index|
            check_line(line, index)
          end
        end

        def check_line(line, index)
          return if match_uris(line)

          add_offense(nil, index, MSG)
        end

        def match_uris(string)
          matches = []
          string.scan(uri_regexp) do
            matches << $LAST_MATCH_INFO if valid_uri?($LAST_MATCH_INFO[0])
          end
          matches
        end

        def valid_uri?(uri_ish_string)
          URI.parse(uri_ish_string)
          true
        rescue
          false
        end

        def uri_regexp
          @regexp ||= URI.regexp(cop_config['Sources'])
        end
      end
    end
  end
end

spec/rubocop/cop/acme/approved_supermarkets_spec.rb:

# encoding: utf-8

require 'spec_helper'

describe Rubocop::Cop::ACME::ApprovedSupermarkets do
  subject(:cop) { described_class.new }
  let(:cop_config) { cop_config }

  cop_config['Sources'].each do |source|
    it 'accepts #{source} as an authorized supermarket' do
      inspect_source(cop, "source '#{source}'")
      expect(cop.offenses).to be_empty
    end
  end
end

Berksfile (which should fail)

source 'https://supermarket.untrusted.com'

metadata

We'd like to write several other internal cops, which is why I chose to develop a RuboCop plugin vs. adding an issue to the RuboCop project. Any help is appreciated.

score 0 · Answer 1 · answered Sep 22 '16 at 14:36

Here's a solution which seems to work for now. Hopefully, it helps someone else.

lib/rubocop/cop/acme/allowed_supermarkets.rb

# encoding: utf-8
# frozen_string_literal: true

require 'uri'

module RuboCop
  module Cop
    module ACME
      # This cop checks that only allowed supermarkets are used within Berksfiles.
      #
      # The default regexp for an acceptable allowed supermarkets can be found in
      # config/default.yml.  The default can be changed in your .rubocop.yml as follows:
      #
      # ACME/AllowedSupermarkets:
      #   Sources:
      #     - 'https://supermarket.acme.com'
      #     - 'https://supermarket.trusted.com'
      #
      class AllowedSupermarkets < Cop
        MSG = 'Only the use of authorized Chef Supermarkets are allowed.'.freeze

        def investigate(processed_source)
          processed_source.lines.each_with_index do |line, index|
            next unless line.start_with?('source')

            range = source_range(processed_source.buffer,
                                 index + 1,
                                 (line.rstrip.length)...(line.length))

            add_offense(range, range, MSG) unless match_uri(line)
          end
        end

        def match_uri(string)
          string.match(uri_regexp) { |m| true if valid_uri?(m[0]) }
        rescue
          false
        end

        def valid_uri?(uri_ish_string)
          URI.parse(uri_ish_string)
          true
        rescue
          false
        end

        def uri_regexp
          @regexp = Regexp.union(cop_config['Sources'])
        end
      end
    end
  end
end

Custom RuboCop to search for configurable URLs?

1 Answers1