The most important consideration in program testing is the design and creation of effective test cases. Testing, however creative and seemingly complete, cannot guarantee the absence of all errors. Test‐case design is so important because complete testing is impossible. In other way round, a test of any program must be necessarily incomplete. The obvious strategy, then, is to try to make tests as complete as possible. Given constraints on time and cost, there is a variety of key issues of testing. This chapter introduces the concept of test‐case design and discusses the various test‐case design techniques such as: Logic coverage, Equivalence partitioning, Boundary value analysis and Cause‐effect graphing. Once one has agreed that aggressive software testing is a worthy addition to the development efforts, the next step is to design test cases that will exercise the application sufficiently to produce satisfactory test results. In most cases, one should consider a combination of black‐box and white‐box methodologies to ensure that one has designed rigorous program testing.