module Test::Unit::Diff

def diff(differ_class, from, to, options={})
  if from.respond_to?(:valid_encoding?) and not from.valid_encoding?
    from = from.dup.force_encoding("ASCII-8BIT")
  end
  if to.respond_to?(:valid_encoding?) and not to.valid_encoding?
    to = to.dup.force_encoding("ASCII-8BIT")
  end
  differ = differ_class.new(from.split(/\r?\n/), to.split(/\r?\n/))
  lines = differ.diff(options)
  if Object.const_defined?(:EncodingError)
    begin
      lines.join("\n")
    rescue EncodingError
      lines.collect {|line| line.force_encoding("ASCII-8BIT")}.join("\n")
    end
  else
    lines.join("\n")
  end
end

def fold(string)
  string.split(/\r?\n/).collect do |line|
    line.gsub(/(.{78})/, "\\1\n")
  end.join("\n")
end

def folded_readable(from, to, options={})
  readable(fold(from), fold(to), options)
end

def need_fold?(diff)
  /^[-+].{79}/ =~ diff
end

def readable(from, to, options={})
  diff(ReadableDiffer, from, to, options)
end

def unified(from, to, options={})
  diff(UnifiedDiffer, from, to, options)
end