implementation under test; IUT
Technical term in software testing; refers to the specific system, component, or code being tested.
Run unit tests against the implementation under test.
Verify that the implementation under test works correctly.
More general term for 'test target'; 試験対象 is more formal and often used in standards or documentation.
system under test; SUT
Compound of 試験 (test) and 対象 (target, object). A straightforward modern technical term.