So look at
There’s no Checks API check run for invalid an YAML, making it look like all CI/integrations checks are green. But in fact Travis CI just didn’t post anything to GitHub.
Now, I get that one can notice this at https://travis-ci.com/ansible/molecule/requests but this requires (1) knowledge that it’s there and (2) being attentive to see it on time. Current requests page view doesn’t show any errors either because this happened 2 days ago and there’s only a limited amount of requests shown there.
I think that travis should post a check run earlier than starting the build, on the stage of the YAML config parsing.
Also, you could use annotations to report parse errors right in diff: