public function testCheckSkipEmpty()
{
$rules = array('email' => array('email', 'skipEmpty' => true, 'message' => 'email is not valid'));
// empty string should pass
$data = array('email' => '');
$result = Validator::check($data, $rules);
$this->assertEmpty($result);
// null value should pass
$data = array('email' => null);
$result = Validator::check($data, $rules);
$this->assertEmpty($result);
// string with spaces should NOT pass
$data = array('email' => ' ');
$result = Validator::check($data, $rules);
$this->assertNotEmpty($result);
}