[saalweachter]

If your engineers don't write tests, it also probably means that they are not being rewarded for writing tests or punished for not writing tests; indeed, if they are rewarded for doing things that are not writing tests (such as pushing new features) and they can do those things without writing tests, they are being rewarded for not writing tests.

Just telling engineers, "write tests" and then promoting the ones that don't is bad leadership: you need to create an environment where the behaviors you desire are the ones that are promoted.