public function testWriteExpiryExpires()
{
$now = time();
$keys = array('key1' => 'data1');
$time = $now + 5;
$expiry = "@{$now} +5 seconds";
$this->File->write($keys, $expiry);
$file = Libraries::get(true, 'resources') . '/tmp/cache/key1';
$expected = "{:expiry:{$time}}\ndata1";
$result = file_get_contents($file);
$this->assertEqual($expected, $result);
}