Zoho CRM has the sandbox feature, while Zoho Desk has not. The best alternative to a sandbox for Zoho Desk seems to be to create a dummy department (and name it sandbox or something) on your paid account or to use a Desk trial account. 

However, it is not clear to me what steps one needs to take to build a fully working test environment where the "test-crm" integrates with the "test-desk" and where the set-up of the test environment doesn't affect the live-CRM or the live-Desk. That should also be true for widgets in CRM that talk to Desk and vice versa: they should work both in the live and in the test-environment, without the need to maintain two code-sets. At the worst, it should be possible for the widget code to detect whether it is invoked in the live or in the test system, but again, I don't know what the API is for that.

Anyone who has some good advice on setting up an integrated test environment for the combination of Desk and CRM?

Tnx