Also if possible include a unit test in the PR, maybe even in a separate commit. For example, let's say I'm a project maintainer and I get a PR with two commit

Also if possible include a unit test in the PR, maybe even in a separate commit. For example, let's say I'm a project maintainer and I get a PR with two commits. The first commit just adds a test case, and Travis has marked the build for that commit as failed. The second commit includes a fix for that case and Travis shows that the tests pass when run on that commit. That's the sort of PR I can confidently merge without even having to leave GitHub's web UI.