schacon/ruby-git

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'optparse'

# A script used to test calling a command line program from Ruby
#
# This script is used to test the `Git::CommandLine` class. It is called
# from the `test_command_line` unit test.
#
# --stdout: string to output to stdout
# --stderr: string to output to stderr
# --exitstatus: exit status to return (default is zero)
# --signal: uncaught signal to raise (default is not to signal)
# --duration: number of seconds to sleep before exiting (default is zero)
#
# Both --stdout and --stderr can be given.
#
# If --signal is given, --exitstatus is ignored.
#
# Examples:
# Output "Hello, world!" to stdout and exit with status 0
#    $ bin/command_line_test --stdout="Hello, world!" --exitstatus=0
#
# Output "ERROR: timeout" to stderr and exit with status 1
#   $ bin/command_line_test --stderr="ERROR: timeout" --exitstatus=1
#
# Output "Fatal: killed by parent" to stderr and signal 9
#   $ bin/command_line_test --stderr="Fatal: killed by parent" --signal=9
#
# Output to both stdout and stderr return default exitstatus 0
#   $ bin/command_line_test --stdout="Hello, world!" --stderr="ERROR: timeout"
#

# The command line parser for this script
#
# @example
#   parser = CommandLineParser.new
#   options = parser.parse(['--exitstatus', '1', '--stderr', 'ERROR: timeout', '--duration', '5'])
#
# @api private
class CommandLineParser
  def initialize
    @option_parser = OptionParser.new
    @duration = 0
    define_options
  end

  attr_reader :duration, :stdout, :stderr, :exitstatus, :signal

  # Parse the command line arguements returning the options
  #
  # @example
  #   parser = CommandLineParser.new
  #   options = parser.parse(['major'])
  #
  # @param args [Array<String>] the command line arguments
  #
  # @return [CreateGithubRelease::Options] the options
  #
  def parse(*args)
    begin
      option_parser.parse!(remaining_args = args.dup)
    rescue OptionParser::InvalidOption, OptionParser::MissingArgument => e
      report_errors(e.message)
    end
    parse_remaining_args(remaining_args)
    # puts options unless options.quiet
    # report_errors(*options.errors) unless options.valid?
    self
  end

  private

  # @!attribute [rw] option_parser
  #
  # The option parser
  #
  # @return [OptionParser] the option parser
  #
  # @api private
  #
  attr_reader :option_parser

  def define_options
    option_parser.banner = "Usage:\n#{command_template}"
    option_parser.separator ''
    option_parser.separator "Both --stdout and --stderr can be given."
    option_parser.separator 'If --signal is given, --exitstatus is ignored.'
    option_parser.separator 'If nothing is given, the script will exit with exitstatus 0.'
    option_parser.separator ''
    option_parser.separator 'Options:'
    %i[
      define_help_option define_stdout_option define_stderr_option
      define_exitstatus_option define_signal_option define_duration_option
    ].each { |m| send(m) }
  end

  # The command line template as a string
  # @return [String]
  # @api private
  def command_template
    <<~COMMAND
      #{File.basename($PROGRAM_NAME)} \
        --help | \
        [--stdout="string to stdout"] [--stderr="string to stderr"] [--exitstatus=1] [--signal=9]
    COMMAND
  end

  # Define the stdout option
  # @return [void]
  # @api private
  def define_stdout_option
    option_parser.on('--stdout="string to stdout"', 'A string to send to stdout') do |string|
      @stdout = string
    end
  end

  # Define the stderr option
  # @return [void]
  # @api private
  def define_stderr_option
    option_parser.on('--stderr="string to stderr"', 'A string to send to stderr') do |string|
      @stderr = string
    end
  end

  # Define the exitstatus option
  # @return [void]
  # @api private
  def define_exitstatus_option
    option_parser.on('--exitstatus=1', 'The exitstatus to return') do |exitstatus|
      @exitstatus = Integer(exitstatus)
    end
  end

  # Define the signal option
  # @return [void]
  # @api private
  def define_signal_option
    option_parser.on('--signal=9', 'The signal to raise') do |signal|
      @signal = Integer(signal)
    end
  end

  # Define the duration option
  # @return [void]
  # @api private
  def define_duration_option
    option_parser.on('--duration=0', 'The number of seconds the command should take') do |duration|
      @duration = Integer(duration)
    end
  end

  # Define the help option
  # @return [void]
  # @api private
  def define_help_option
    option_parser.on_tail('-h', '--help', 'Show this message') do
      puts option_parser
      exit 0
    end
  end

  # An error message constructed from the given errors array
  # @return [String]
  # @api private
  def error_message(errors)
    <<~MESSAGE
      #{errors.map { |e| "ERROR: #{e}" }.join("\n")}

      Use --help for usage
    MESSAGE
  end

  # Output an error message and useage to stderr and exit
  # @return [void]
  # @api private
  def report_errors(*errors)
    warn error_message(errors)
    exit 1
  end

  # Parse non-option arguments (there are none for this parser)
  # @return [void]
  # @api private
  def parse_remaining_args(remaining_args)
    report_errors('Too many args') unless remaining_args.empty?
  end
end

options = CommandLineParser.new.parse(*ARGV)

STDOUT.puts options.stdout if options.stdout
STDERR.puts options.stderr if options.stderr
sleep options.duration unless options.duration.zero?
Process.kill(options.signal, Process.pid) if options.signal
exit(options.exitstatus) if options.exitstatus