Hi,
It's recommended to separate test and production environment. to avoid any impact and risk on your production environment when you want test and validate a task or a product.
It's recommended to install the test environment in separate VLAN. The test and staging environment should not have a connection with production environment.
If you want build a test environment similar to production , you have two option:
- backup one of the DC from production domain and restore it in test VLAN. Then you perform metadata cleaup to remove other DC and size FSMO role.
- Create new forest and domain with same functional level and feature as the production envirement.
Please don't forget to mark this reply as answer if it help you