public function testSingleField()
{
$this->specify('Test date validator with single field.', function () {
$validation = new Validation();
$validation->add('date', new Date());
$messages = $validation->validate(['date' => '2016-06-05']);
expect($messages->count())->equals(0);
$messages = $validation->validate(['date' => '2016-06-32']);
expect($messages->count())->equals(1);
});
}