Citrix offers a complete solution to perform load tests in XenApp and XenDesktop environments: Citrix EdgeSight for Load Testing.
This product is available on the Citrix website; at the moment I'm writing the latest version, 3.8.1.
You need a valid XenApp license to download and run the product. It's included in the Enterprise or Platinum version
Using EdgeSight for Load Testing, you are able to simulate real user sessions to analyze how your farm performs with different loads; it's a very helpful tool to correctly design your infrastructure.
EdgeSight for Load Testing has two components: