In performing quality control and quality assurance testing there are different objectives that drive the methods employed. To ensure that quality objectives are met it’s necessary to verify that work was performed as required and the possibility of malfunction is mitigated or non-existent. These methodologies are termed constructive and destructive testing. Both should be employed in order to achieve complete quality.
Constructive testing involves ensuring that work was performed correctly and that the basic functions of the area repaired work as required. For example brakes provide the function of stopping the vehicle, steering to change the direction of the vehicle, etc. Constructive testing ensures that the basic requirements of a repaired item function as expected
Destructive testing involves attempting to cause a malfunction. When a repair is performed there’s a possibility that there may be a failure under certain conditions. Running at top speed, braking suddenly or turning sharply are examples of extreme conditions that may cause a failure. Destructive testing should be employed to ensure top quality when appropriate.
Integration testing focuses on evaluating the impact of repairs performed on other potentially affected areas. For example changing a time belt may affect the water pump, tensioner, etc. If the other related components don’t need to be replaced then they should not be. But testing for quality should include making sure that these related areas are sound. This will involve performing quality control testing on these areas even though they weren’t changed.
Employing multiple methodologies will ensure quality objectives are met. Costs incurred in the course of quality testing should always be considered as there’s always the danger of overdoing it. But the type and size of repair should impact the decision on how much time to invest in quality. The more significant the repair or the more risk involved the more effort should be devoted to quality.