To do local development of elm-upgrade, you will need nodejs, python, jq, rsync, and git. They should all be available via your system's package manager.
Then, install cram (which requires python):
pip install cram
cram --version
# Cram CLI testing framework (version 0.7)
And install the node dependencies:
npm install
npm test
npm install
npm link
You should now have elm-upgrade
on your path.