Cachearium\Backend\CacheNull::singleton PHP Method

    public static function singleton()
    {
        static $instances;
        if (!isset($instances)) {
            $instances = new CacheNull();
        }
        return $instances;
    }

 public function testCacheNull()
 {
     $key = new CacheKey('any', 'thing');
     $cache = CacheNull::singleton();
     $this->assertInstanceOf('Cachearium\\Backend\\CacheNull', $cache);
     $cache = CacheAbstract::factory('Null');
     $this->assertInstanceOf('Cachearium\\Backend\\CacheNull', $cache);
     try {
         $cache->get($key);
         $this->assertTrue(false);
     } catch (Cachearium\Exceptions\NotCachedException $e) {
         $this->assertTrue(true);
     }
     $this->assertEquals(5, $cache->increment(1, $key, 5));
     $this->assertTrue($cache->store(10, $key));
     $this->assertTrue($cache->delete($key));
     $this->assertTrue($cache->clean($key));
     $this->assertTrue($cache->clear());
     $this->assertFalse($cache->start($key));
     $cache->end();
     $cache->prefetch(array());
     $cache->enable(true);
 }