Files
stack/packages/mosaic/framework/tools/git/test-wrapper-guard.sh
T
Hermes Agent 96609bdade
ci/woodpecker/pr/ci Pipeline failed
framework: prove the wrapper guard both ways, and resolve its wrappers relatively
Two defects found by running the guard rather than reading it.

1. The guard resolved its sibling wrappers through a hardcoded
   $HOME/.config/mosaic/tools/git. On a host with no installed mosaic home — a
   CI container, a bare checkout — every wrapper lookup missed, `[ -x ]` failed,
   and the guard fell through allowing the raw API write it exists to block. It
   failed OPEN, silently, in exactly the environment least likely to notice.
   It now resolves relative to its own path, so it names the wrappers from the
   install it was launched from, with $HOME as the fallback.

2. There was no test. Adding one surfaced the guard's other sharp edge
   immediately: it matches the literal text of the Bash command, so a harness
   that embeds a blocked pattern inline trips the guard on itself rather than on
   the fixture. That is the correct fail-closed posture and it is now recorded in
   the test's own comments, because the next person will hit it too.

test-wrapper-guard.sh asserts twelve fixtures and asserts the ALLOWED cases as
hard as the blocked ones. A guard that over-blocks gets routed around and a guard
that under-blocks is decoration; only pinning both edges keeps it useful. It is
hermetic — no network, no credentials, no repository — so it joins the CI
sanitization step directly rather than the exclusions file.
2026-08-12 16:54:18 -05:00

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#!/usr/bin/env bash
# test-wrapper-guard.sh — hermetic behavioural regression for wrapper-guard.sh.
#
# Resolves no credentials, touches no network, and creates no repository: the
# guard reads a hook payload on stdin and answers with an exit code, so the whole
# contract is testable from fixtures.
#
# The fixtures are written to a temp file rather than passed inline, and this is
# not stylistic. The guard inspects the literal text of the Bash command it is
# handed. A test that embeds `git clone ... $HOME` inside its own command line
# trips the guard on the harness instead of on the fixture — which is exactly
# what happened the first time this was checked by hand. Substring matching over
# whole command text is the guard's deliberate fail-closed posture; a test that
# does not account for it silently measures the wrong thing.
#
# Exit: 0 = every fixture behaved as specified · 1 = at least one did not
set -uo pipefail
HERE="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
GUARD="${1:-$HERE/wrapper-guard.sh}"
[ -x "$GUARD" ] || { printf 'test-wrapper-guard: not executable: %s\n' "$GUARD" >&2; exit 2; }
TMP="$(mktemp -d)"; trap 'rm -rf "$TMP"' EXIT
FIXTURES="$TMP/fixtures.tsv"
# Each line: <expected-exit> TAB <hook payload> TAB <what it proves>
# 0 = allowed, 2 = blocked.
{
printf '2\t{"tool_input":{"command":"git clone https://example.invalid/x ~/wt"}}\tcheckout into $HOME is refused\n'
printf '2\t{"tool_input":{"command":"git worktree add ~/wt topic"}}\tworktree into $HOME is refused\n'
printf '0\t{"tool_input":{"command":"git clone https://example.invalid/x /src/wt"}}\tcheckout onto a work filesystem is fine\n'
printf '0\t{"tool_input":{"command":"curl -s -X GET https://git.example.invalid/api/v1/repos/a/b/pulls/1"}}\treads are never blocked\n'
printf '2\t{"tool_input":{"command":"curl -X POST -d @b https://git.example.invalid/api/v1/repos/a/b/pulls/1/reviews"}}\treview write has a wrapper\n'
printf '2\t{"tool_input":{"command":"curl -X POST -d @b https://git.example.invalid/api/v1/repos/a/b/pulls/1/merge"}}\tmerge write has a wrapper\n'
printf '2\t{"tool_input":{"command":"curl -X POST -d @b https://api.github.com/repos/a/b/issues"}}\tGitHub host is covered too\n'
printf '0\t{"tool_input":{"command":"curl -X POST -d @b https://git.example.invalid/api/v1/repos/a/b/releases"}}\tan endpoint with no wrapper passes\n'
printf '2\t{"tool_input":{"command":"curl -X POST -d {\\"event\\":\\"APPROVE\\"} https://example.invalid/x"}}\tthe APPROVE token is caught anywhere\n'
printf '0\t{"tool_input":{"command":"ls -la /src"}}\tordinary commands are untouched\n'
printf '0\t{"tool_input":{"command":"MOSAIC_WRAPPER_OVERRIDE=1 curl -X POST -d @b https://git.example.invalid/api/v1/repos/a/b/pulls"}}\tbreak-glass works\n'
printf '0\t{"tool_input":{}}\tan empty payload does not block the session\n'
} > "$FIXTURES"
fail=0 n=0
while IFS=$'\t' read -r want payload why; do
[ -n "${want:-}" ] || continue
n=$((n + 1))
printf '%s' "$payload" | "$GUARD" >/dev/null 2>&1
got=$?
if [ "$got" = "$want" ]; then
printf 'ok %s\n' "$why"
else
printf 'FAIL %s (want exit %s, got %s)\n' "$why" "$want" "$got"
fail=1
fi
done < "$FIXTURES"
printf '\n'
if [ "$fail" -eq 0 ]; then
printf 'wrapper-guard: %d/%d fixtures behaved as specified.\n' "$n" "$n"
else
cat <<'EOF'
wrapper-guard drifted from its contract.
A guard that blocks too much gets routed around, and a guard that blocks too
little is decoration. Both directions are failures here, which is why the
allowed cases are asserted as hard as the blocked ones.
EOF
fi
exit "$fail"