> - it contains executable, and dir with text files
> - each text file describe one test

Sounds like a language to be defined first. If I would create a test
suite, first I would
find the smallest peaces of code to be implemented in a native language
like C or C++.

These peaces reflect typical or untypical usecases of the SQLXXX API.

As I have some experience using plugins, I would suggest to implement
these test
peaces as plugins to be loaded by the name of the test.

To have more flexibility, I would define a language to get test data
for it, but delegate
the handling of the test to the plugin.

Regards,

Lothar