I merged branch develop into branch my-feature with the following command:
$ git merge --no-ff develop
$ git status
On branch my-feature
Your branch is ahead of 'origin/my-feature' by 3 commits.
(use "git push" to publish your local commits)
nothing to commit, working directory clean
git merge --log
You can use
git log origin/my-feature..my-feature
to see the commits that are in your branch, but have not yet been pushed (the ahead commits).
Since you are already on
my-feature though, you can shorten it to:
git log origin/my-feature..