This is how!

wget -O speedtest-cli https://raw.github.com/sivel/speedtest-cli/master/speedtest_cli.py
chmod +x speedtest-cli
./speedtest-cli

This are what results might look like

[root@stream4 ~]# ./speedtest-cli
Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Fundacao para a Ciencia e a Tecnologia (193.137.171.XX)...
Selecting best server based on ping...
Hosted by Vodafone PT (Porto) [56.28 km]: 12.239 ms
Testing download speed........................................
Download: 80.28 Mbit/s
Testing upload speed..................................................
Upload: 80.26 Mbit/s