proc runtest_exit_code { test_name command_line exit_code } {

  exec ./mcc $command_line.cpp

  spawn $command_line
  
  expect eof
 
  exec rm $command_line
 
  lassign [wait] pid spawnid os_error_flag value
  
  if {$os_error_flag == 0} {
    if {$value == $exit_code} {
      pass "$test_name: Returned expected value $value"
    } else {
      fail "$test_name: Returned bad value $value, expected: $exit_code"
    }
  } else {
    fail "$test_name: errno: $value"
  }

}