think\Debug::getUseMem PHP Method

    public static function getUseMem($dec = 2)
    {
        $size = memory_get_usage() - THINK_START_MEM;
        $a = ['B', 'KB', 'MB', 'GB', 'TB'];
        $pos = 0;
        while ($size >= 1024) {
            $size /= 1024;
            $pos++;
        }
        return round($size, $dec) . " " . $a[$pos];
    }

 /**
  * @covers think\Debug::getUseMem
  * @todo Implement testGetUseMem().
  */
 public function testGetUseMem()
 {
     $useMem = \think\Debug::getUseMem();
     $this->assertLessThan(13, explode(" ", $useMem)[0]);
 }