TDD-ed CSS comment weeder

comment_weeder_test.rb

require 'test/unit'

class CommentWeeder
  def initialize
    reset
  end

  def process(char)
    @trail += char

    start_comment if @trail.end_with? '/*'
    reset if @trail.end_with? '*/'

    flush unless ignore?(char)
  end

  private

  def start_comment
    @comment = true
  end

  def reset
    @comment = false
    @trail = ""
  end

  def ignore?(char)
    @comment || char == '/'
  end

  def flush
    output = @trail
    reset
    output
  end
end

class CommentWeederTests < Test::Unit::TestCase

  def setup
    @m = CommentWeeder.new
  end

  def test_returns_normal_char
    assert_equal 'h', @m.process('h')
  end

  def test_returns_noncomment
    assert_equal 'b', @m.process('b')
    assert_equal 'y', @m.process('y')
    assert_equal 'e', @m.process('e')
  end

  def test_returns_nil_on_slash
    assert_equal nil, @m.process('/')
  end

  def test_returns_a_star_normally
    assert_equal '*', @m.process('*')
  end

  def test_returns_nil_for_star_after_slash
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
  end

  def test_returns_last_two_for_nonstar_after_slash
    assert_equal nil, @m.process('/')
    assert_equal '/a', @m.process('a')
  end

  def test_returns_nil_for_comment_body
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('h')
  end

  def test_continues_nil_for_second_comment_opener
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('b')
    assert_equal nil, @m.process('y')
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('e')
  end

  def test_returns_nil_for_comment_body_with_second_star
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('h')
    assert_equal nil, @m.process('*')
  end

  def test_returns_nil_for_comment_body_with_closing_comment
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('h')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('/')
  end

  def test_resumes_output_after_closing_comment
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('h')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('/')
    assert_equal 'i', @m.process('i')
  end

  def test_two_comments # t/*h*/i/*s*/z => tiz
    assert_equal 't', @m.process('t')
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('h')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('/')
    assert_equal 'i', @m.process('i')
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('s')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('/')
    assert_equal 'z', @m.process('z')
  end

  # seems to work ... any edge cases? even if not valid css...

  def test_weird_open_closer # /*no*/*yes
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('n')
    assert_equal nil, @m.process('o')
    assert_equal nil, @m.process('*')
    assert_equal nil, @m.process('/')
    assert_equal '*', @m.process('*')
    assert_equal 'y', @m.process('y')
    assert_equal 'e', @m.process('e')
    assert_equal 's', @m.process('s')
  end

  def test_lots_of_slashes
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('/')
    assert_equal nil, @m.process('/')
    assert_equal '///h', @m.process('h')
  end
end