Integrate with common_test?

[evnu]

We should evaluate if it is possible to hook up doctest with common_test. Maybe ct_hooks can be used for integration.

[evnu]

Maybe the best way to integrate this with common_test would be to generate _SUITE modules. With this, integrating with common_test is only another build step, which is simple. OTOH, this pollutes the test directory with generated files. This could be circumvented by placing the files in a specific "generated tests" directory.