class Test::Unit::Diff::ReadableDiffer

def find_diff_line_info(from_start, from_end, to_start, to_end)
  best_ratio = default_ratio
  from_equal_index = to_equal_index = nil
  from_best_index = to_best_index = nil
  to_start.upto(to_end - 1) do |to_index|
    from_start.upto(from_end - 1) do |from_index|
      if @from[from_index] == @to[to_index]
        from_equal_index ||= from_index
        to_equal_index ||= to_index
        next
      end
      matcher = SequenceMatcher.new(@from[from_index], @to[to_index],
                                    &method(:space_character?))
      if matcher.ratio > best_ratio
        best_ratio = matcher.ratio
        from_best_index = from_index
        to_best_index = to_index
      end
    end
  end
  [best_ratio,
   from_equal_index, to_equal_index,
   from_best_index,  to_best_index]
end