# Coverage measured by name, and what it found was failing open

> On main since rc2: Coverage measured by name, and what it found was failing open. Test coverage was being measured the flattering way.

Source: https://kern-lang.eu/releases/coverage-measured-by-name

On main since rc2

## Release notes

Test coverage was being measured the flattering way. A new by-name measurement over the standard library asked a blunter question, which functions does no test ever reach, and answered **710 public functions**. Working through that list in batches did what a coverage number never does on its own: it found code that had never worked. `std.graph` **had never compiled**. So had `std.integrity`, a documented security module that was, in practice, dead code.

All four of a decoder family **failed open** on malformed input, as did `jwt_payload` and `base64url_decode`, which is the worst possible direction for an auth primitive. `pg_ping`, `pg_is_connected` and `check_db` reported the **inverse of reality**, so a health check called a dead database healthy. `List == List` was always true and read out of bounds while doing it (now E0318). Builtin dispatch hijacked any stdlib function whose name happened to match a C symbol. A private stdlib function poisoned that name everywhere it appeared.

The test harness itself reported a perfect `PASS` when handed a non-executable compiler. Each is now fixed and pinned, and the tooling learned from it: `W0002` warns on an import that names nothing the module exports, with a location, and the resolver's module-name guard stopped rejecting 27 legitimate files. This is the unglamorous half of a trust claim, and the register is kept in public: coverage is reported as two axes with the remaining gaps recorded as **open validations, not gated exclusions**.