source: drbl_ui/backup/test_busybox/busybox-1.7.2/testsuite/tr/tr-works

run_tr ()
{
  echo -n "echo '$1' | tr '$2' '$3': "
  echo "$1" | $bb tr "$2" "$3"
  echo
}
tr_test ()
{
  run_tr "cbaab"    abc     zyx
  run_tr "TESTING A B C"  '[A-Z]'   '[a-z]'
  run_tr "abc[]"    "a[b"     AXB
  run_tr abc    '[:alpha:]'   A-ZA-Z
  run_tr abc56    '[:alnum:]'   A-ZA-Zxxxxxxxxxx
  run_tr 012    '[:digit:]'   abcdefghi
  run_tr abc56    '[:lower:]'   '[:upper:]'
  run_tr "  " '[:space:]'   12345
  run_tr "  " '[:blank:]'   12
  run_tr 'a b'    '[= =]'   X
  run_tr "[:"   '[:'    ab
  run_tr "  .,:"  '[:punct:]' 12
  run_tr "  .,:"  '[:cntrl:]' 12
}

bb=        tr_test > logfile.gnu
bb=busybox tr_test > logfile.bb
diff -u logfile.gnu logfile.bb