Suppose you are on the master branch and you would like to test if the dev branch can be merged without conflict into the master.
# In the master branch
git merge dev --no-ff --no-commit
After that, you will be able to know if there’s a conflict or not.
To return in a normal situation, just abort the merge:
git merge --abort
According to the git documentation:
--ff
Do not generate a merge commit if the merge resolved as a fast-forward, only update the branch pointer. This is the default behavior.
-no-ff
Generate a merge commit even if the merge resolved as a fast-forward.
--commit
Perform the merge and commit the result. This option can be used to override –no-commit.
--no-commit
With –no-commit perform the merge but pretend the merge failed and do not autocommit, to give the user a chance to inspect and further tweak the merge result before committing.