This is a very practical question, but all the answers above are not practical.

Like

git checkout master
git pull origin master
git merge test
git push origin master

This approach has two issues:

1. It's unsafe, because we don't know if there are any conflicts between test branch and master branch.

2. It would "squeeze" all test commits into one merge commit on master; that is to say on master branch, we can't see the all change logs of test branch.

So, when we suspect there would some conflicts, we can have following git operations:

git checkout test
git pull 
git checkout master
git pull
git merge --no-ff --no-commit test

Test merge before commit, avoid a fast-forward commit by --no-ff,

If conflict is encountered, we can run git status to check details about the conflicts and try to solve

git status

Once we solve the conflicts, or if there is no conflict, we commit and push them

git commit -m 'merge test branch'
git push

But this way will lose the changes history logged in test branch, and it would make master branch to be hard for other developers to understand the history of the project.

So the best method is we have to use rebase instead of merge (suppose, when in this time, we have solved the branch conflicts).

Following is one simple sample, for advanced operations, please refer to http://git-scm.com/book/en/v2/Git-Branching-Rebasing

git checkout master
git pull
git checkout test
git pull
git rebase -i master
git checkout master
git merge test

Yep, when you have uppers done, all the Test branch's commits will be moved onto the head of Master branch. The major benefit of rebasing is that you get a linear and much cleaner project history.

The only thing you need to avoid is: never use rebase on public branch, like master branch.

Never do operations like the following:

git checkout master
git rebase -i test

Details for https://www.atlassian.com/git/tutorials/merging-vs-rebasing/the-golden-rule-of-rebasing

appendix:

• if you are not sure about rebasing operations, please refer to: https://git-scm.com/book/en/v2/Git-Branching-Rebasing

Maybe you should not merge?

1. Checkout branch_1
2. Rebase master changes into branch_1
3. Fix any errors that might have occured after testing your code
4. Checkout master
5. Rebase branch_1 changes into master

or in code:

git checkout branch_1
git rebase master
(...)
git checkout master
git rebase branch_1

This also gives you the opportunity to squash several commits into one, if you want to make your changesets more dense, and prevents these annoying merge-commits in your history.