How have other customers tested HireRight integration during Implementation

Summary:

We are using HireRight as our employment verification vendor for our implementation and they have told us that they don't have a test environment for our upcoming test event to be able to validate the integration. They have said that they only recognize go live as a major milestone which means that the first time that this integration will be tested with real life scenario will be at Go-Live. This is a huge risk to the project as you never want to test an integration just at go-live.

Curious on how other customers have dealt with this and been able to test with HireRight without a testing environment from them.