One of the rights in the customer bill of rights tells the customer he will be able to see progress in the form of a
working system that passes repeatable tests that he specifies. These tests are what we call the Customer Tests. The
customer specifies one or more Customer Tests for each user story in the system, describing in detail how each story is
expected to work. Because the tests are put into executable form and are fully automated, they tell programmers what
needs to be done in a unambiguous way (tests pass or fail) and allow the customer to feel confident that the system is
meeting his needs.
Ability to see tangible and verifiable progress.
Ultimate traceability: the Customer Tests are executable system requirements.
Repeatability: because they are automated, the tests can be run at any time.