Meanwhile I wrote a prototype of a lightweight test runner. https://github.com/SO3Group/vytest
It takes a test directory that contains a config file that defines what data and scripts should be copied to remote router, copies it over SFTP into /config/scripts/vytest and runs scripts.
It’s not a replacement for expect-style testing tools, but rather a complementary tool. Running tests on the target instead of emulating the user preserves more information about failures and allows deeper testing of the underlying components.
example/ directory is an example of what a test can look like.
If you are feeling like QA, feel free to play with it. VyOS test suite is going to be public, and we will accept test scripts from contributors.