Add more thorough testing

[dequbed]

As a reasonable approximation "more testing" = "more good" does hold. And rsasl already does some testing but it could definitely profit from more.

Especially as it's a rather abstract framework integration tests are relevant to make sure updates don't break stuff.

Especially integration tests that just test the client portion of a mechanism against its server portion should be a good place to start as they won't require knowledge of the inner workings of the mechanisms or rsasl itself.

[duesee]

Would you be interested in a PR that adds fuzz-testing to rsasl? Fuzz-testing everything that is potentially exposed to untrusted data seems like a good start.

[dequbed]

Oh absolutely :)

I was looking into fuzz testing rsasl a while back, the main reason why I didn't go for it was that it currently doesn't expose any of the mechanisms directly so I felt like it'd mostly fuzz test the parsers. But that too would be a benefit so if you want to help with it, please do! ^^