Tests and Requirements, Requirements and Tests: A Möbius Strip

W hen Donald Gause and Gerald Weinberg wrote this statement,1 they were asserting that writing tests is an effective way to test requirements’ completeness and accuracy. They also suggest writing these tests when gathering, analyzing, and verifying requirements—long before those requirements are coded. They go on to say, “We can use the black box concept during requirements definition because the design solution is, at this stage, a truly black box. What could be more opaque than a box that does not yet exist?”1 Clearly, they value early test