To help assuring the quality of the tests that are created or modified in the AGILE mindset, the branch merging system should have a review process.
QA team could have a reviewer status and be required to analyse the changes before they are merged to master test suite.
Since QA's and developers are usually not testing in the same way.
This would be a great tool to assure that the transition from a QA only test management to a dev contribution test managent does not affect the quality of the test base.
By reviewing the branches, QA would be able to identify wrong methods, pair with the dev and explain tests best practices.