Integration Test Order Strategies to Consider Test Focus and Simulation Effort

The integration testing process aims at uncovering faults within dependencies between the components of a software system. Due to the lack of resources, it is usually not possible to test all dependencies. Fault prone dependencies have to be selected as test focus. This test focus has to be considered during the stepwise integration of the whole software system. An integration test order strategy has to devise an integration order that integrates dependencies selected as test focus in early integration steps. Furthermore the strategy has to minimize the effort to simulate not yet integrated components of the software system. Current approaches only focus on the reduction of the simulation effort, but do not take into account the test focus. This paper introduces an approach to determine an optimal integration testing order that considers both, the test focus and the simulation effort. The approach is applied to nine real software systems and the results are compared to six approaches.