In the last chapter, we talked about programmer tests, those low-level tests that help programmers make sure they have written the code right. How do they know the right thing to build? In phased and gated methodologies, we try to solve that by gathering requirements up front and putting as much detail in them as possible. In projects using agile practices, we put all our faith in story cards and tests that customers understand in order to help code the right thing. These “understandable” tests are the subject of this chapter.