I have tried a variety of things to speed it up, and noticed that single tests could be sped up by 50%, but once running in parallel (testssl.sh mode, not parallel bats which I think I observed before as slowing it down even further), the difference is much less.

Changing to a different base image for testssl showed about 40 seconds or more improvement for me, although I've also been observing a smaller improvement once the base image upgrades to a newer version of Alpine, I'm not 100% sure but it appears to be due to musl vs glibc for the most part.

We can potentially look at splitting the test case up into multiple files grouped in a folder instead (with the methods extracted out into a helper) for bats to run in parallel (each test case runs testssl.sh in parallel on 7 ports though). Alternatively splitting the testssl.sh parallel tests from 7 at once into to two separate runs of 3 and 4 might be another option. I've observed 10-15 seconds for a port to be tested locally, vs around 40-ish for all 7 in parallel, so it's hard to say they'd be much improvement 😅

For CI at least, we can always leverage more runners to spread out those test cases 🤔

Another option is to only run those tests only when relevant files would affect it for PRs, while master branch could run on each merge and raise an issue if the test failed.