test(corpus): make the CORPUS_DIR gates report when they skip

[h4x0r]

Dependency form — resolved

The forensic-testgate dev-dependency was a path dep pointing at a machine-local scratch
directory, so cargo metadata failed on every other machine and every CI job died at manifest
load before running a single check.

forensic-testgate 0.1.0 published to crates.io on
2026-08-02, so the dep is now the registry form this PR originally promised:

forensic-testgate = "0.1"

A git-pinned revision was the alternative, and was rejected. A git dep carries no publisher record,
so cargo-vet would need an [[exemptions]] entry where a trust entry applies — the weaker
mechanism, which ADR-0018 treats as a defect when a stronger one is available — and the dep would
have had to be swapped a second time once the registry version landed.

Supply chain: the crate is ours and published by h4x0r, which is ADR-0018 mechanism (2), so it
gets [[trusted.forensic-testgate]] scoped to safe-to-run (it is a dev-dependency).

The loud-skip contract is unchanged — with CORPUS_DIR unset the tests still announce the skip by
name, and FORENSIC_TESTGATE_STRICT=1 still turns each skip into a failure.

Why

core/tests/corpus.rs stacked two silent skips in every corpus test:

let Some(dir) = corpus_dir() else { return };   // CORPUS_DIR unset  — silent
let path = dir.join("dynamic.vhd");
if !path.exists() { return; }                    // fixture absent   — silent

cargo test prints ok whether the VHD reader was validated against the real corpus or never opened a file. Those are not the same claim, and the suite could not tell you which one you got.

This is one instance of a fleet-wide pattern: a sweep found 216 env-gated test skip sites that produce no output at all. This exact corpus_dir() helper is cloned verbatim in qcow2-forensic, vhdx-forensic, and vmdk-forensic; this is the vhd instance. Companion PR: SecurityRonin/qcow2-forensic#4.

What changed

Both halves now resolve through forensic_testgate::gated_file. The notice is emitted by the resolver, on the library side of the seam, so there is no quiet variant to reach for and a later edit cannot drop it.

CORPUS_DIR	Behaviour
unset	notice naming the variable, skip, exit 0
set, fixture absent	notice naming the directory and the fixture, skip
set to a missing path	FAILS, naming the variable and showing the value

The third is the deliberate design call: setting the variable is the operator saying run this test, so a path that is not there is a misconfiguration, not a skip. The escape hatch is leaving the variable unset.

Verification

$ cargo test -p vhd-core --test corpus -- --nocapture
SKIP [forensic-testgate]: CORPUS_DIR is unset — this test did not run. Set CORPUS_DIR to the fixture it gates on to run it.
SKIP [forensic-testgate]: CORPUS_DIR is unset — this test did not run. Set CORPUS_DIR to the fixture it gates on to run it.
SKIP [forensic-testgate]: CORPUS_DIR is unset — this test did not run. Set CORPUS_DIR to the fixture it gates on to run it.
test corpus_dynamic_vhd_opens_and_has_nonzero_size ... ok
test corpus_fixed_vhd_opens_and_has_nonzero_size ... ok
test corpus_dynamic_vhd_read_is_stable ... ok
test dynamic_fixture_reports_dynamic_disk_type ... ok
test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

Full suite: 55 passed. clippy --all-targets --all-features -D warnings clean.

Separate finding — a gate that has never fired in CI

Not fixed here, to keep this diff reviewable. core/tests/qemu_differential.rs:19 and :98 hardcode the oracle path:

const QEMU_IMG: &str = "/opt/homebrew/bin/qemu-img";
if !Path::new(QEMU_IMG).exists() { return; }

That is the macOS-ARM Homebrew path only, so on the Linux CI runner it never exists and the qemu differential tests silently skip on every CI run — they have never validated anything in CI. qcow2-forensic/core/tests/real_images.rs already fixed this exact bug by searching /opt/homebrew, /usr/local and /usr/bin, with a comment noting the hardcoded path "made the oracle tests skip on the Linux CI runner, dropping coverage." The same defect is live in vhdx-forensic and qcow2-forensic's forensic/ crate.

Worth its own PR, along with a loud tool-resolution gate so the next occurrence announces itself.

🤖 Generated with Claude Code

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	forensic-testgate@​0.1.0

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