How to properly deploy to battle?

Question

git

Hello.
There is such data:
1) the project is created on Bitbucket, then everyone clones it for themselves, also for the fight
2) the master branch is on the fight, all developers work in dev or their branches
3) now the deployment happens like this git checkout dev -> git pull origin dev -> git
checkout master -> git merge dev, because of this, a lot of jambs get into production managers are testing.

Answer 1

How do you test?