obviously you need to connect two end devices - each one to each switch and run some network benchmark tool like iperf or similar.
as the switches have usually quite more overall throughput in comparison to throughput of single link, then you have to focus on end devices and cables. In order to achieve maximum speed from 1Gbps link you have to consider to use CAT6 cables instead of CAT5E which are more than recommended for 1Gbps speeds. Before starting with tests be sure, that speed on each link is correctly negotiated to 1Gbps.
Another factor which could affect testing results are the network cards on end devices - use more credible vendors like Intel or Broadcom to make sure you get most accurate results.
