I guess I'm gradually converting to team- #formalmethods.
I've been writing tests for many years, and I'm very happy with how much better my dev experience has become. Both as a developer and reviewer.
I even spent a year building the coolest testing library for #Scheme.
But the more I work with tests, the more I realize that I want strictier and more declarative way to express system invariants.
The talk reinforces my feelings: