Test the get feature.
public function testGet() {
$cached = $this->chain
->get('t123');
$this
->assertNotIdentical(FALSE, $cached, 'Got key that is on all backends');
$this
->assertIdentical(1231, $cached->data, 'Got the key from the backend 1');
$cached = $this->chain
->get('t23');
$this
->assertNotIdentical(FALSE, $cached, 'Got key that is on backends 2 and 3');
$this
->assertIdentical(232, $cached->data, 'Got the key from the backend 2');
$cached = $this->chain
->get('t3');
$this
->assertNotIdentical(FALSE, $cached, 'Got key that is on the backend 3');
$this
->assertIdentical(33, $cached->data, 'Got the key from the backend 3');
}