/**
  * Returns with the source's adapter
  *
  * @return AdapterInterface
  */
 public function getAdapter()
 {
     return $this->source->getAdapter();
 }
 public function testFlush()
 {
     $this->assertNull($this->kvs->flush());
 }
 public function testSet()
 {
     $this->assertFalse($this->kvs->set('key', 'value'));
 }
 public function testPersist()
 {
     $this->assertFalse($this->kvs->persist('key'));
 }