class Test::Unit::Diff::UnifiedDiffer

def format_summary(operations, show_context)
  _, first_from_start, _, first_to_start, _ = operations[0]
  _, _, last_from_end, _, last_to_end = operations[-1]
  summary = "@@ -%d,%d +%d,%d @@" % [first_from_start + 1,
                                     last_from_end - first_from_start,
                                     first_to_start + 1,
                                     last_to_end - first_to_start,]
  if show_context
    interesting_line = find_interesting_line(first_from_start,
                                             first_to_start,
                                             :define_line?)
    summary << " #{interesting_line}" if interesting_line
  end
  summary
end