`zero doctor`'s runtime check returned StatusPass unconditionally with a
hardcoded "go" label — it verified nothing (the running binary, a version,
anything), so it was a false-confidence green: "Zero Go runtime is available
(go)" no matter what (#405).
Make it real: resolve the running binary via os.Executable, stat it, and report
the resolved PATH plus the actual Go version — failing loudly if the path can't
be resolved, the file has vanished, or it's a directory. os.Executable/os.Stat
are injectable (Options.Executable/StatExecutable) so the check is testable
without a real on-disk layout.
Note on scope: doctor runs INSIDE the native binary, so it cannot diagnose the
binary being ABSENT at install time — that case is already caught earlier and
loudly by the npm wrapper (bin/zero.js refuses to launch, present since v0.1.0),
which is why the issue's literal "doctor passes while binary missing" repro does
not occur. The real defect this fixes is the tautological check; surfacing the
binary path is the useful part (spotting an npm-installed binary vs a stale or
shadowing copy on PATH) instead of a meaningless pass. The caller now passes the
real runtime.Version() rather than the "go" placeholder.
Tests: present-binary passes and reports the path; missing/inaccessible binary,
unresolvable os.Executable, and a directory path each FAIL (red-green — the old
code passed unconditionally); the default (uninjected) path resolves the real
running binary.
Fixes#405
Gnanam
2a5b2af277