msd-core/tests/no-unbounded-spawn-allowlist.test.cjs

// allow-test-rule: structural-regression-guard [#3143]
/**
 * no-unbounded-spawn-allowlist.test.cjs
 *
 * Structural guards on `eslint-rules/no-unbounded-spawn.allowlist.json` —
 * matrix D4-D8 of
 * .gsd/phase/chore-3143-no-unbounded-spawn-guard/50-test-matrix.md.
 *
 * D7 needs to inspect test-file *contents* for an inline directive that
 * disables this rule by name — the absence of that pattern is the contract
 * this guard protects (a contributor cannot silence the check by disabling
 * it inline instead of fixing the timeout). That is a `readFileSync` +
 * text-search on `.cjs` files, which is exactly what `local/no-source-grep`
 * exists to catch — hence the
 * `// allow-test-rule: structural-regression-guard [#3143]` annotation on
 * its own line above, per CONTRIBUTING.md's documented exemption.
 */

'use strict';

const { describe, test } = require('node:test');
const assert = require('node:assert/strict');
const fs = require('fs');
const path = require('path');

const ALLOWLIST_PATH = path.join(__dirname, '..', 'eslint-rules', 'no-unbounded-spawn.allowlist.json');
const TESTS_DIR = path.join(__dirname);
const REPO_ROOT = path.join(__dirname, '..');

// The allowlist only ratchets DOWN. This baseline is the length observed at
// the time this guard was written (139 entries) — each future migration
// wave lowers it as files are moved off the allowlist by adding real
// timeouts; it must never grow back up. Lowered to 120 by the #3144 Wave-1
// process-seam migration (19 files' unbounded spawns bounded), then to 73
// by the #3145 Wave-2 migration (47 files' unbounded spawns bounded), then
// to 49 by the #3147 Wave-3 migration (24 files' unbounded spawns bounded).
const BASELINE = 49;

function readAllowlist() {
  const raw = fs.readFileSync(ALLOWLIST_PATH, 'utf8');
  return JSON.parse(raw);
}

function listTestFiles() {
  const out = [];
  for (const entry of fs.readdirSync(TESTS_DIR, { withFileTypes: true })) {
    if (entry.isFile() && entry.name.endsWith('.cjs')) {
      out.push(path.join(TESTS_DIR, entry.name));
    }
  }
  return out;
}

// Pure detection helpers, extracted so each is unit-testable against a
// synthetic fixture — proving the check itself can fail, not only that
// today's real data happens to pass it (a check that never runs against an
// injected violation is a vacuous-truth risk).

function findDeadEntries(list, root) {
  return list.filter((entry) => !fs.existsSync(path.join(root, entry)));
}

function findBackslashEntries(list) {
  return list.filter((entry) => entry.includes('\\'));
}

function isSorted(list) {
  return JSON.stringify(list) === JSON.stringify([...list].sort());
}

function findDuplicates(list) {
  const seen = new Set();
  const dupes = new Set();
  for (const entry of list) {
    if (seen.has(entry)) dupes.add(entry);
    seen.add(entry);
  }
  return [...dupes];
}

// Built via concatenation, not a string literal, so this file does not
// itself contain the literal directive text (`local/no-unbounded-spawn`)
// that D7 below scans every test file for — a literal here would make this
// guard flag itself.
const GUARDED_RULE = 'local' + '/' + 'no-unbounded-spawn';

function containsDisableDirective(contents, ruleName) {
  return new RegExp(`eslint-disable[^\\n]*${ruleName}`).test(contents);
}

describe('no-unbounded-spawn allowlist: D4 — no dead entries', () => {
  test('every allowlist entry resolves to a file that exists on disk', () => {
    const list = readAllowlist();
    const dead = findDeadEntries(list, REPO_ROOT);
    assert.deepEqual(dead, [], `dead allowlist entries (file does not exist): ${JSON.stringify(dead)}`);
  });

  test('detection logic actually flags a synthetic dead entry', () => {
    const synthetic = ['tests/does-not-exist-xyz.test.cjs', 'tests/no-unbounded-spawn.test.cjs'];
    const dead = findDeadEntries(synthetic, REPO_ROOT);
    assert.deepEqual(dead, ['tests/does-not-exist-xyz.test.cjs']);
  });
});

describe('no-unbounded-spawn allowlist: D5 — never grows', () => {
  test('allowlist length is at or under the recorded baseline', () => {
    const list = readAllowlist();
    assert.ok(
      list.length <= BASELINE,
      `allowlist grew to ${list.length} entries, exceeding the BASELINE of ${BASELINE}. ` +
        `The allowlist only ratchets down — if this is a legitimate new violation, ` +
        `lower BASELINE only after confirming it, never raise it to paper over growth.`
    );
  });
});

describe('no-unbounded-spawn allowlist: D6 — separator normalization', () => {
  test('every entry uses / separators, never \\', () => {
    const list = readAllowlist();
    const withBackslash = findBackslashEntries(list);
    assert.deepEqual(withBackslash, [], `entries with a backslash separator: ${JSON.stringify(withBackslash)}`);
  });

  test('detection logic actually flags a synthetic backslash entry', () => {
    const synthetic = ['tests\\foo.test.cjs', 'tests/bar.test.cjs'];
    assert.deepEqual(findBackslashEntries(synthetic), ['tests\\foo.test.cjs']);
  });
});

describe('no-unbounded-spawn allowlist: D7 — no inline disable of this rule', () => {
  test('no test file inline-disables the unbounded-spawn guard', () => {
    const offenders = [];
    for (const filePath of listTestFiles()) {
      const contents = fs.readFileSync(filePath, 'utf8');
      if (containsDisableDirective(contents, GUARDED_RULE)) {
        offenders.push(path.relative(REPO_ROOT, filePath));
      }
    }
    assert.deepEqual(
      offenders,
      [],
      `test files inline-disabling the unbounded-spawn guard (forbidden — fix the timeout instead): ${JSON.stringify(offenders)}`
    );
  });

  test('detection logic actually flags a synthetic inline-disable directive', () => {
    const syntheticContents = [
      "'use strict';",
      '// eslint-disable-next-line ' + GUARDED_RULE,
      "spawnSync('git', ['status'], {});",
    ].join('\n');
    assert.equal(containsDisableDirective(syntheticContents, GUARDED_RULE), true);
    assert.equal(containsDisableDirective("'use strict';\nspawnSync('git', ['status'], {});", GUARDED_RULE), false);
  });
});

describe('no-unbounded-spawn allowlist: D8 — canonical form', () => {
  test('allowlist is valid JSON, sorted, with no duplicates', () => {
    const list = readAllowlist();
    assert.ok(Array.isArray(list), 'allowlist.json must parse to an array');
    assert.ok(isSorted(list), 'allowlist entries must be sorted');
    assert.deepEqual(findDuplicates(list), [], 'allowlist entries must be unique');
  });

  test('detection logic actually flags a synthetic unsorted/duplicate list', () => {
    assert.equal(isSorted(['b.test.cjs', 'a.test.cjs']), false);
    assert.deepEqual(findDuplicates(['a.test.cjs', 'b.test.cjs', 'a.test.cjs']), ['a.test.cjs']);
  });
});