Add exit-code assertion to excluded test-file fixture test #30

Finding

The test default mode skips unsafe_type_assertion in test files (tests/ai-slop-detector.behavior.test.ts:413-431) only asserts on stdout content but does not verify the process exit code. The sister test default mode still reports unsafe_type_assertion in non-test files already asserts result.status === 1.

Without an explicit exit-code assertion, the test can pass when the process fails without producing the checked stdout text (e.g., crash before emitting output).

Evidence

// Current — no exit-code assertion:
try {
    assert.ok(!result.stdout.includes('unsafe_type_assertion'),
      "should not report as any in test files. stdout: " + result.stdout);
} finally { ... }

// Sister test — already has exit-code assertion for status 1:
try {
    assert.equal(result.status, 1, ...);
    ...
}

Requirements

The excluded test-file test must assert result.status === 0 before the stdout check, including stderr in the failure message.

Constraints

• Do not alter production exit-code behavior.
• Do not weaken the existing stdout assertion.
• Do not remove or change the sister test's exit-code assertion.
• Do not combine with unrelated test changes.

Validation

The test must fail (RED) if the fixture file has an actual finding and the process would exit non-zero, and pass (GREEN) when the finding is correctly excluded and the process exits 0.

Rollback

A reverted test-only commit restores current coverage.