Feature flag code detection

flag_registration.rb

# https://gist.github.com/synth/8c9eee23aa9df535aa42a30f7cff9ba9
require "parser/current"
module Flipper
  module FlagRegistration
    # These functions are all memoized because they should be static for the
    # lifetime of a deployment (albeit they are really static to a Ruby process)
    def self.registered_flags
      @registered_flags ||= YAML.load_file("config/feature_flags.yml")
    end

    def self.registered_flags=(flags)
      File.write("config/feature_flags.yml", flags.to_yaml)
    end

    def self.flags_in_code
      @flags_in_code ||= begin
        search_regex = 'Flipper.enabled\?\([^\)]+\)'
        command = "grep -rohE --exclude-dir='.//.*' --include='*rb' '#{search_regex}' ./"
        results = `#{command}`
        lines = results.split("\n")
        lines.filter_map { |line|
          ast = Parser::CurrentRuby.parse(line)
          ast.children[2].children[0]&.to_s
        }.sort.uniq
      end
    end

    def self.registered_flags_not_found
      @registered_flags_not_found ||= flags_in_code - registered_flags.keys.map(&:to_sym)
    end

    def self.flags_not_registered
      @flags_not_registered ||= flags_in_code - registered_flags.keys.map(&:to_sym)
    end
  end
end