One of the main principles of Agile methodologies consists in the early and continuous delivery of valuable software by short time-framed iterations. After each iteration, a working product is delivered according to the requirements defined at the beginning of the iteration. Testing tools facilitate the task of checking if the system provides the expected behavior according to the specified requirements. However, since testing tools need to be adapted in order to test new working products in each iteration, a significant effort has to be invested. This work presents a Software Product Line Engineering (SPLE) approach that allows flexibility in the adaption of testing tools with the working products in an iterative way. A case study is also presented using PLUM (Product Line Unified Modeller) as the tool suite for SPL implementation and management.