Make sure you have docker, python, and pip. I won't cover how to install those here, please search the internet for that info if you need it.
Travis-ci auto runs tests during pull requests (PR) but it only has 2 cores and if you have more/faster cpus your PC's local tests will be faster and you'll have quicker feedback loops than continually pushing to have your PR run travis-ci
After you have the prereqs, to get the required pip packages run: pip install -r requirements.txt
To run the Dockerfile templating, image build, and tests all in one command just run: tox
Docker images built by tox or python Dockerfile.py are named the same but stripped of the pihole/ docker repository namespace.
e.g. pi-hole:debian_amd64 or pi-hole-multiarch:debian_aarch64
You can run the multiarch images on an amd64 development system if you enable binfmt-support as described in the multiarch image docs
docker run --rm --privileged multiarch/qemu-user-static:register --reset