public function is($exp1, $exp2, $message = '')
  {
    if (is_object($exp1) || is_object($exp2))
    {
      $value = $exp1 === $exp2;
    }
    else if (is_float($exp1) && is_float($exp2))
    {
      $value = abs($exp1 - $exp2) < self::EPSILON;
    }
    else
    {
      $value = $exp1 == $exp2;
    }

    if (!$result = $this->ok($value, $message))
    {
      $this->set_last_test_errors(array(sprintf("           got: %s", var_export($exp1, true)), sprintf("      expected: %s", var_export($exp2, true))));
    }

    return $result;
  }