I wanted to set up Travis CI long time ago. Finally, I have a chance to do so. There are already many posts on how to do it. I write it down here for my own future reference. Thanks Tao Liu for the instructions. I have been learning a lot from him in collabrating with the MAESTRO project.
read the official documentation https://docs.travis-ci.com/user/tutorial/
Jean Fan’s blog post https://jef.works/blog/2019/02/17/automate-testing-of-your-R-package/
R specific https://docs