test fixture
A jig, often spring pins on test pads, that powers and tests each board on the line.
A test fixture is the mechanical and electrical jig, often a bed of spring-loaded pogo pins on test pads, that connects each unit to the test and programming equipment on a production line.
Examples
A greenhouse node board is pressed onto a test fixture's spring pins, powered, and checked before any eFuse is burned.
Testing on the fixture comes before locking, so a board with a bad sensor can still be reflashed or repaired.