Interesting approach, but I don’t think writing your tests in a bash framework is long term that much better than using a more full featured language. I can see how some people might prefer bash, but I think that if you need to get into complicated assertions and workflows you’re going to want a more full featured language.
Perl is probably the most widely installed option. Python is good. For many people even go would be great (I can pretty much always assume a 64bit linux environment, but that’s just me).
I hadn’t thought to use go, but the combination features makes it pretty compelling for this case: