In #3950 , we've built a mechanism for running the combined set of tests for the framework as well as all commands, which now resides in https://github.com/wp-cli/phar-build .

• Have test system download built nightly Phar: wget -O ...
• Rename repository to reflect sole purpose as running the full test suite.
• Configure Travis to run on a nightly basis.
• Set up Slack notifications for build failures.