Too fast is wrong

probatum is a test-oriented check runner I build in Rust. One issue waited forty-two days: there was no way to fail a response that came back too fast. For a login endpoint verifying an Argon2 hash, that is the only assertion that matters — swap the hash for a string compare and every test stays green while the endpoint gets a hundred times faster. Four releases in three days closed it, and along the way fixed a runner that only read the first 100,000 lines of what it was checking.