Acceptance Testing: Don t Trust Developers

Acceptance Testing: Don't Trust Developers

Most of the questions the players ask about the stories are related to the acceptance criteria of the story. The coach (acting as the customer) tells the players how he will test whether a story is implemented correctly. For the balloons, there are pieces of string to measure whether the balloon is big enough. For the paper-folding stories, there are prototypes of the boat and hat to be folded.

Some stories look so easy that no explanation is necessary. But what do we mean by a "sorted deck of cards?" Is the ace the first or the last card? Do we need to put the different suits in some order? The team has to agree with the customer/coach up front to estimate the difficulty of the story.

When the team has implemented a story, the coach explicitly performs the acceptance test: The sorted deck is verified; the folded hats are compared with the prototype; the balloons are measured with the piece of string. When the implementation doesn't pass the test, the team must continue the implementation. Even the simplest tasks can be implemented incorrectly, so an acceptance test failure underscores the importance of testing.