and we don't know what is the quality of end code, it is possible that tech debt created by migration is well higher than 1.5 eng/y.
I’ve done something similar to this type of work with an llm. It produces code that is often too idiomatic, in that it introduces conventional approaches that are overkill for the task at hand. But this is almost an ideal scenario, because if the previous tests run clean, the newly converted tests can only fail by being wrong.
They can also silently reduce the tested scenarios, but that’s what code reviews are for.
> They can also silently reduce the tested scenarios, but that’s what code reviews are for.
code review of complicated scenarios is about as resource demanding as actually writing code, so shrinking time spent from 1.5y to 6 weeks totally can produce lower quality.
Seriously, the wishful thinking around this stuff is embarassing.