QA can add a lot of value to an agile team because of the different mindset. Testers can and should think about the different possible scenarios to test a story. However the most important asset that they can bring is:

☛ To prevent defect. QA should advocate best practices along the way to prevent defects from entering the system in the first place.

☛ To provide fast feedback. It is important for developers to know if the new functionality works as expected and if regression tests pass, and they need that feedback quite quickly. QA should provide the results of the tests to developers as soon as possible.