Generate scaffold for new cop

generate_cop.rake

desc "Create a RuboCop rule using a template. You can use snake_case or CamelCase for the cop name; either way it will be converted to CamelCase."
task :generate_cop, [:name] do |_t, args|
  require "active_support/inflector/methods"
  camel_case_name = ActiveSupport::Inflector.camelize(args[:name], true)
  snake_case_name = ActiveSupport::Inflector.underscore(camel_case_name)

  cop_path = "lib/rubocop/cop/<company name>/#{snake_case_name}.rb"
  spec_path = "spec/rubocop/cop/<company name>/#{snake_case_name}_spec.rb"
  raise ArgumentError, "Cannot create cop -- file <#{cop_path}> already exists." if File.exist?(cop_path)
  raise ArgumentError, "Cannot create spec -- file <#{spec_path}> already exists." if File.exist?(spec_path)

  File.open(cop_path, "w") do |f|
    f.write(<<~COP)
      module RuboCop
        module Cop
          module CompanyName
            # Description of what this cop does
            #
            # Can be multi-line
            #
            # @example
            #
            #   # bad
            #   <example of bad code>
            #
            #   # good
            #   <example of good code>
            #
            class #{camel_case_name} < Cop
              MSG = "Failure message".freeze
            end
          end
        end
      end
    COP
  end

  File.open(spec_path, "w") do |f|
    f.write(<<~SPEC)
      require "spec_helper"

      RSpec.describe RuboCop::Cop::CompanyName::#{camel_case_name} do
        subject(:cop) { described_class.new(config) }

        let(:config) { RuboCop::Config.new }

        context "when under some conditions" do
          it "does not register an offense" do
            skip("Specs are required for all cops.")

            expect_no_offenses(<<~RUBY)
              <good code>
            RUBY
          end
        end

        context "when under other conditions" do
          it "registers an offense" do
            skip("Specs are required for all cops.")

            expect_offense(<<~RUBY)
              <bad code>
              ^^^^^^^^^^ <Failure message>
            RUBY
          end
        end
      end
    SPEC
  end

  File.open("lib/rubocop-companyName.rb", "a") do |f|
    f.write("require \"rubocop/cop/<company name>/#{snake_case_name}\"\n")
  end

  File.open("config/default.yml", "a") do |f|
    f.write(<<~YAML)

      CompanyName/#{camel_case_name}:
        Enabled: true
    YAML
  end
end