If you have **macOS Monterey or later** in your system, here is how you can test Internet speed:- 

1. Go to **Terminal**
2. Type `networkQuality -v` and Press **Enter**

You will see internet speed test running inside your terminal & returning the result within a minute.

Sample Output:-

    ==== SUMMARY ====                                                                                         
    Upload capacity: 18.856 Mbps
    Download capacity: 98.696 Mbps
    Upload flows: 20
    Download flows: 12
    Responsiveness: Low (121 RPM)
    Base RTT: 273
    Start: 28/11/21, 1:06:09 AM
    End: 28/11/21, 1:06:28 AM
    OS Version: Version 12.0.1 (Build XXXXXX)

(Source: https://support.apple.com/en-gb/HT212313)

UPDATED:- In case you are willing to test in **earlier versions of macOS**, just run the following in your terminal.

    curl -s https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | python -