In your role as integrator, you are responsible for building the work delivered by developers, creating baselines, and testing those baselines. To perform rigorous testing, such as regression testing, create a development stream to be used solely for testing baselines. This practice provides a stable environment for testing and does not stall the delivery of work to parent streams and the project integration stream.
If you make baselines in the integration stream to perform testing, lock the stream to prevent developers from delivering work. This practice ensures that you work with a static set of files. It is acceptable to perform quick validation tests of the new baselines in the integration stream. However, you should not lock the integration stream for a long time because you will create a backlog of deliver operations.