Here is a sequence of commands that could become a test:

    temp_dir=$(mktemp -d -t git-integration)
    pushd $temp_dir
    git init
    git commit --allow-empty -m 'An initial commit'
    git checkout -b branch-a master
    git commit --allow-empty -m 'A commit on branch-a'
    git checkout -b branch-b master
    git commit --allow-empty -m 'A commit on branch-b'
    git checkout master
    git integration --create integration
    git integration --add branch-a
    git integration --add branch-b
    git integration --rebuild
    git log --topo-order --pretty=format:%s
    test $(git log --topo-order --oneline --pretty=format:%H integration | tail -n +2 | head -n 1) = $(git log --topo-order --oneline --pretty=format:%H branch-b | head -n 1)
    test $(git log --topo-order --oneline --pretty=format:%H integration | tail -n +4 | head -n 1) = $(git log --topo-order --oneline --pretty=format:%H branch-a | head -n 1)
    test $(git log --topo-order --oneline --pretty=format:%H integration | tail -n +5 | head -n 1) = $(git log --topo-order --oneline --pretty=format:%H master | head -n 1)

I see quite a few existing formulas that do nothing more than execute a single command with a `--version` argument or similar. If you'd still like me to incorporate something like the above into this formula, could you point me at a good similar test that could serve as a guide?