We currently do not have a dedicated sandbox or test environment.
Our current workaround is for you to create a second account to be used as a test account. When creating this second account, please add UAT to the end of the Organisation name.
This will then provide you with an alternate Portal and API Key, allowing you to test all processes and API calls, without affecting your live environment.
The Orders endpoint can be tested by keeping "type": "validate". This will allow you to test if the call would have been valid, without reducing your Organisation credit balance. More information on this can be found in the following article: How To Test The API Ordering Process.