Customer (Acceptance) Tests

Customer tests (or, as we also call them, acceptance tests) are defined by the customers. Their purpose is to test every story, to provide the customer with confidence that the story is correctly implemented. Customer tests are supposed to be automated and run regularly to catch regressions as the system evolves.

Are Customer Tests Essential?

In my opinion these tests are quite important, indeed essential. Here's why.

• Customer tests are part of the process of defining requirements. They provide an unambiguous statement of what the program is expected to do. Without them, your risk of defects goes way up.

• Customer tests give the customer confidence. Without them, the customer has to rely too much on trust instead of knowledge.

• Customer tests, when they fail, provide valuable input for how to improve the programmer unit tests.

Running without acceptance tests is running out of control.