code: private static function isEmptyArrayEquivalent($expected, $actual)
      {
          return (gettype($expected) == 'string')
              && ((gettype($actual) == 'array') || (gettype($actual) == 'NULL'))
              && empty($actual)
              && empty($expected);
      }
docs: Check if the actual argument is of type array and empty and the expected value is of type string and also empty.
  
  @param mixed $expected The expected value.
  
  @param mixed $actual   The actual value.
  
  @return bool