require 'diff/lcs'
require 'diff/lcs/hunk'

data_old = [ 'hello', 'one', 'two', 'three', 'goodbye']
data_new = [ 'hello', 'oNE', 'three', 'goodbye']
diffs = Diff::LCS.diff(data_old, data_new)

file_length_difference = 0
oldhunk = nil
hunk = nil
output = ''

diffs.each do |piece|
    begin
        hunk = Diff::LCS::Hunk.new(data_old, data_new, piece, 3, file_length_difference)
        file_length_difference = hunk.file_length_difference
        next unless oldhunk
        if hunk.overlaps?(oldhunk)
            hunk.unshift(oldhunk)
        else
            output << oldhunk.diff(:unified)
        end
    ensure
        oldhunk = hunk
        output << "\n"
    end
end

output << oldhunk.diff(:unified)
output << "\n"
puts output