Component Integration Testing | ISTQB Test Levels Explained
At component integration testing, the focus is on the communications between components or units. For the developers, the order in which they test the interactions, will necessarily depend on the order in which the components will be built. This order can be top-down (thus from system level to method level at each component), bottom-up (opposite of top-down, from methods up to overall system level) or big-bang (where testing takes place after integration of several units; this is not regarded as an efficient or desirable integration test strategy).
Objectives – to discover defects and failures in the interactions between components
Typical defects and failures – continuing with our drop-down box example, an integration defect could be that the code has omitted to include the drop-down box for some items; the failure will then be that the drop-down box is not displayed when an item has been selected.
Specific approaches and responsibilities – since testing here is focused on code, as for component testing, it is most often carried out by the developers in their environments, with test harnesses and frameworks being used to assist with the integration testing.
New to this series? Start with our previous article on Component (Unit) Testing, where we explain how individual units are tested before they are integrated.