upper tester
Computing term for a testing tool or component that operates at a higher level in a test hierarchy.
This upper tester is used to verify the operation of the entire system.
Compound of 上位 (じょうい, 'upper level') + 試験 (しけん, 'test') + 手段 (しゅだん, 'means'). A technical term likely coined in software or hardware testing contexts.