What is Integration Testing?
Take a 3/8” bolt with a fine thread and a hexagonal head. Count its threads, measure its width, count the sides on its head, everything checks out. This bolt is machined to an exact specification, and has no flaws in it’s design or form. Take a 1/2” coarse threaded hole, examine it the same. Perfectly machined, perfectly designed to perform it’s function. Both parts have no flaws, no defects, but when put together they’re essentially useless. They don’t fit together.
What Is Its Purpose?
The basic nature of integration testing is not to see how individual components work, but to see how those components or even entire systems fit together. It checks that the nuts match the bolts and the engine takes the oil. No matter how well made a part is, it is useless if it does not fit into the machine as a whole. It is also useless if it does not fit into all the machines it is supposed to fit into. We perform rigorous integration testing in order to root out defects and errors caused by interacting software components in a system and to ensure the system works on all technical platforms within which it will be implemented.