:if linedollar < linecount | exe 'wincmd w' | call append(line('$'), "expected " . linecount . " lines but found only " . linedollar) | exe 'wincmd w' | let linecount = linedollar | endif
:let i = 1
:while i <= linecount | if getline(i) != i . text | exe 'wincmd w' | call append(line('$'), i . ' differs') | exe 'wincmd w' | endif | let i += 1 | endwhile