从 macOS 12 开始，networkQuality 命令就内置在系统中了，直接运行这个命令就会开始测速，连接的域名是 mensura.cdn-apple.com。
$ networkQuality
==== SUMMARY ====
Uplink capacity: 498.647 Kbps
Downlink capacity: 277.112 Mbps
Responsiveness: Low (1.156 seconds | 51 RPM)
Idle Latency: 33.167 milliseconds | 1809 RPM
参考资料
networkQuality 的服务端是开源的：https://github.com/network-quality/server
