Software Product Line Engineering (SPLE) is an approach used in the development of similar products, which aims at systematic reuse of software artifacts. The SPLE process has several activities executed to assure software quality. Quality assurance is of vital importance for achieving and maintaining a high quality for various artifacts, such as products and processes. Testing activities are widely used in industry for quality assurance. However, the effort for applying testing is usually high, and increasing the testing efficiency is a major concern. A common means of increasing efficiency is automation of test design. Several techniques, processes, and strategies were developed for SPLE testing, but still many problems are open in this area of research. The challenge in focus is the reduction of the overall test effort required to test SPLE products. Test effort can be reduced by maximizing test reuse using models that take advantage of the similarity between products. The thesis goal is to automate the generation of small test-suites with high fault detection and low test redundancy between products. To achieve the goal, equivalent tests are identified for a set of products using complete and configurable test-suites. Two research directions are explored, one is product-based centered, and the other is product line-centered. For test design, test-suites that have full fault coverage were generated from state machines with and without feature constraints. A prototype tool was implemented for test design automation. In addition, the proposed approach was evaluated using examples, experimental studies, and an industrial case study for the automotive domain. The results of the product-based centered approach indicate a reduction of 36% on the number of test cases that need to be concretized. The results of the product line-centered approach indicate a reduction of 50% on the number of test cases generated for groups of product configurations.