In the documentation:
The Homebrew addon correctly handles up-to-date, outdated, and missing packages. Manual Homebrew dependency scripts are error-prone, and we recommend against using them.
However, I have found there are at least three cases where the homebrew addon fails to properly handle things
- When an update is needed because homebrew is out of date, the addon fails to do so automatically. This means I am forced to always specify update: yes in my configurations
- The homebrew addon does not handle when homebrew has a very large install that doesn’t print things for a while, and will kill the build
- The homebrew addon does not retry steps such as timed-out downloads, which are a very common issue with Travis’ unreliable network connections.
In addition we’re 5 years on and the homebrew addon still doesn’t do caching: https://github.com/travis-ci/travis-ci/issues/1961
We also see issues like missing features like: Support forced link in homebrew addon