How to test throughput speed without internet?

Is there a program or way to test my 2 wifi cards speeds without being connected to the internet?

I have 1 internal wifi.. and a 2nd Usb wifi that is broadcasting/sharing internet..

I want to see what the maximum speed the 2nd USB wifi card sends throughput to whoever is connected to it..

is there a way to do this offline or do I only need to be online and run a speedtest ..

Give this a look: Wireless Witch: How to Test Your Wireless Performance | PCMag.com

Thanks