minitest.rb

#!/usr/bin/env ruby
#

require 'optparse'
require 'minitest/autorun'

class Chatty

  attr_reader :args

  def initialize(args)
    @args = args
  end

  def say_something
    puts "Mary had a little lamb"
  end

  def be_loud
    warn "Blow your house down!"
  end

  def option_parser
    @option_parser ||= OptionParser.new do |opt|
      opt.banner = "Usage: #{File.basename($0)} [option]"

      opt.on('-V', '--version', "Display the version number.") do
        puts "MiniTest example v0.0.1"
        exit
      end

      opt.on('-h', '--help', "Display this message.") do
        puts opt
        exit
      end
    end
  end

  def parse_options
    if args.empty?
      warn "I don't know what to do"
      warn option_parser
      exit
    end

    option_parser.parse!(args)
  end

end


class ChattyIntegrationTest < MiniTest::Unit::TestCase

  # This works as advertized
  def test_output_of_stdout
    chat = Chatty.new []
    out, _ = capture_io do
      chat.say_something
    end

    assert /mary had a little lamb/i =~ out
  end

  # This works as well
  def test_output_of_stderr
    chat = Chatty.new []
    _, err = capture_io do
      chat.be_loud
    end

    assert /blow your house down/i =~ err
  end

  # This causes all tests to disappear
  def test_output_from_optparse_no_args
    # skip
    chat = Chatty.new []
    _, err = capture_io do
      chat.parse_options
    end

    assert /usage:/ =~ err
  end

  # This doesn't work at all
  def test_output_from_optparse_help
    # skip
    chat = Chatty.new ['-h']
    out, _ = capture_io do
      chat.parse_options
    end

    assert /usage:/ =~ out
  end

end