Ruby Light #1

The Ruby Light series is for Ruby code dumps that amuse me for one reason or another, possibly including commentary.

Here's the first one:

redirect_stdio.rb

# See: http://thinkingdigitally.com/archive/capturing-output-from-puts-in-ruby/

require 'stringio'
 
module Kernel
  def capture_stdout(out = StringIO.new)
    begin
      $stdout = out
      yield
    ensure
      $stdout = STDOUT
    end

    out
  end

  def use_my_stdin(instream)
    begin
      $stdin = instream
      yield
    ensure
      $stdin = STDIN
    end

    instream
  end
end

converter_test.rb

require 'lib/redirect_stdio'
require 'lib/converter.rb'

class ConverterTest < Test::Unit::TestCase
  def test_convert
    input_data = [
        [  # headers
            'rank',  # index 0
            '',  # index 1
            '',  # index 2
            '',  # index 3
            '',  # index 4
            '',  # index 5
            'name',  # index 6
            'category',  # index 7
        ],
        [  # data line 0
            '123',  # index 0
            '',  # index 1
            '',  # index 2
            '',  # index 3
            '',  # index 4
            '',  # index 5
            'Foo',  # index 6
            'Bar',  # index 7
        ],
    ]

    converter = Converter.new
    instream = StringIO.new input_data.map{|line| line.join("\t")}.join("\n")
    output = capture_stdout do
      use_my_stdin(instream) { converter.convert }
    end

    input_data[1..-1].each do |data|
      assert_match /^#{data[6]} is rank #{data[0]} in #{data[7]}$/, output.string
    end
  end
end