Extreme Programming (XP) does not have a separate Quality Assurance (QA) team or role. Usually, the programmers perform unit testing, and either the programmers or the customer carries out acceptance testing. The QA team is associated with the project from the very beginning. They want to break the system at the early stage of the development so that customer does not get faulty product.
The role of tester in xp is :
1.part of the team and attends all team sessions
2.an integral part of the planning process.
3.performs pair testing, i.e. collaborates with the developers to get good tests
XP cuts off the QA tester as a separate role. Instead, the programmers build is tested directly by the customer, then it goes out the door for the production release. A well-managed QA department will review the programming teams process. They will make sure that the source code gets reviewed by new people, either by another programmer or the team leader.
As per the XP experts, QA shows customers the system behavior in terms of automated Acceptance Test scripts that can be run at any time, by anyone on the team, including the customers. The customers mention what they want and provides feedback on the results of the Acceptance Tests and the early-version releases they see. When the acceptance tests got passed, we can conclude that the requirements has been met.