ESS - Environmental Stress Screening - is not a test. It is a product level screening process. ESS is part of manufacturing process, that verifies the operational parameters and guard bands of a product from an environmental - temperature, shock, vibration - point of view.
In production, ESS is generally limited to power cycling and Power margining ("power stress") combined with temperature cycling ("thermal stress"). While often advised, the choice of production deployment is best left to the customer to define expected failure rates against the economics of production ESS process.
ESS Fixturing and Integration:
Complete turnkey service available
Temperature, power control and monitoring
High amperage power supplies and power distribution