How to test more than one feature in a feature release?

Question

git

There is a master branch. It has stable production.
There are many task branches and bugs around that are waiting for testing.
A tester (one) can take only one task into the test at a certain point in time.
Tests it, if it passes, the branch is merged into master.
In this case, in the next task that the tester takes, it is necessary to pull the changes from the master (before that, it cannot be tested) The
question is - how to test more than one task at the same time?
How do two testers work?

Answer 1

Make a dev branch,
let the cloud of task branches be around the dev: each branch is tested separately, and then their compatibility with each other is tested (as I understand it, this is the reason why you can’t test a branch without pulling changes from the master).
After QA feedback on the dev branch, merge dev into master.
Better yet, make dev->stage->master.
Test merged branches on the dev, whole releases on the stage.