A component test is an electrical test validating the proper functioning of an electrical component.
Electrical components can be passive components without control function (e.g. resistors, capacitors, inductors) or active components with an influence on the signal strength or a control function (e.g. diodes, transistors, relays).
Depending on the test system, either just the availability of a component can be confirmed (e.g. a diode on a back plane) or resistances of a component can be measured (e.g. RLC measurement). Example: electric compensator in automotive cable harnesses.
In case the test system sends a control signal via power points (see test point) to a relay, it can measure the changes afterwards (different connections, currents or voltages). This is known as a functional test.