public static function setCacheDir($dir)
 {
     Cache::setCacheDir($dir);
 }
 public function test_setCacheDir()
 {
     $cache_dir = APPPATH . 'tests/_ci_phpunit_test/tmp/cache_test';
     Cache::setCacheDir($cache_dir);
     $this->assertEquals(realpath($cache_dir), Cache::getCacheDir());
 }