dashcaddy/dashcaddy-api/__tests__/atomic-write-dc099.test.js

/**
 * DC-099: canonical atomic file writer (src/utils/atomic-write.js).
 *
 * The notification config's two write paths (load-time canonicalization
 * write-back and the UI saveConfig) used plain fs.writeFileSync — a crash or
 * power loss mid-write could leave a truncated/empty notifications.json. The
 * same risk exists in every store that grew its own private
 * _atomicWriteJSON copy (invite-store, user-store, share-store, …).
 *
 * These tests pin the shared writer's contract:
 *   - durability: fsync before rename, exclusive create, 0600 default
 *   - atomicity: destination only ever replaced via rename
 *   - failure: destination untouched, temp cleaned up, error propagated
 *   - JSON helper: single serialization shape (2-space, no trailing newline —
 *     notification-manager._persistCanonicalForm depends on byte-for-byte
 *     idempotence)
 */

'use strict';

const fs = require('fs');
const os = require('os');
const path = require('path');
const { atomicWriteFile, atomicWriteJSON, tmpPathFor } = require('../src/utils/atomic-write');

// Real-FS tests: the actual syscalls, in a private temp dir.
describe('DC-099 atomic-write (real fs)', () => {
  let dir;

  beforeEach(() => {
    dir = fs.mkdtempSync(path.join(os.tmpdir(), 'dc099-atomic-'));
  });

  afterEach(() => {
    fs.rmSync(dir, { recursive: true, force: true });
  });

  test('writes contents and returns the final path', () => {
    const target = path.join(dir, 'state.json');
    const ret = atomicWriteFile(target, '{"a":1}');
    expect(ret).toBe(target);
    expect(fs.readFileSync(target, 'utf8')).toBe('{"a":1}');
  });

  test('replaces an existing file completely (no torn writes possible)', () => {
    const target = path.join(dir, 'state.json');
    atomicWriteFile(target, 'x'.repeat(1000));
    atomicWriteFile(target, 'y'.repeat(10));
    expect(fs.readFileSync(target, 'utf8')).toBe('y'.repeat(10));
  });

  test('creates the file 0600 by default', () => {
    const target = path.join(dir, 'secret.json');
    atomicWriteJSON(target, { ok: true });
    expect(fs.statSync(target).mode & 0o777).toBe(0o600);
  });

  test('honors an explicit mode override', () => {
    const target = path.join(dir, 'public.json');
    atomicWriteFile(target, '{}', { mode: 0o644 });
    expect(fs.statSync(target).mode & 0o777).toBe(0o644);
  });

  test('leaves no temp files behind after success', () => {
    const target = path.join(dir, 'state.json');
    atomicWriteFile(target, 'abc');
    expect(fs.readdirSync(dir).filter((f) => f.includes('.tmp-'))).toEqual([]);
  });

  test('two rapid writes both land (unique tmp names per write)', () => {
    const target = path.join(dir, 'state.json');
    atomicWriteFile(target, 'first');
    atomicWriteFile(target, 'second');
    expect(fs.readFileSync(target, 'utf8')).toBe('second');
  });

  test('atomicWriteJSON serializes 2-space, no trailing newline', () => {
    const target = path.join(dir, 'conf.json');
    atomicWriteJSON(target, { a: { b: 1 } });
    const raw = fs.readFileSync(target, 'utf8');
    expect(raw).toBe('{\n  "a": {\n    "b": 1\n  }\n}');
  });

  test('write failure leaves the destination untouched and cleans the temp file', () => {
    const target = path.join(dir, 'state.json');
    fs.writeFileSync(target, 'ORIGINAL');
    const origWrite = fs.writeSync;
    fs.writeSync = () => {
      throw Object.assign(new Error('ENOSPC: no space left on device'), { code: 'ENOSPC' });
    };
    try {
      expect(() => atomicWriteFile(target, 'NEW-CONTENT')).toThrow(/ENOSPC/);
    } finally {
      fs.writeSync = origWrite;
    }
    expect(fs.readFileSync(target, 'utf8')).toBe('ORIGINAL');
    expect(fs.readdirSync(dir).filter((f) => f.includes('.tmp-'))).toEqual([]);
  });

  test('tmpPathFor: unique per call, hidden dotfile in the same directory', () => {
    const a = tmpPathFor('/data/x.json');
    const b = tmpPathFor('/data/x.json');
    expect(a).not.toBe(b);
    expect(path.dirname(a)).toBe('/data');
    expect(path.basename(a)).toMatch(/^\.x\.json\.tmp-/);
  });
});

// Mocked-FS tests: pin the syscall DISCIPLINE itself (order + flags), which
// the real-fs tests can't observe directly.
describe('DC-099 atomic-write syscall discipline (mocked fs)', () => {
  const calls = [];

  beforeEach(() => {
    calls.length = 0;
    const rec = (name, impl) =>
      jest.spyOn(fs, name).mockImplementation((...args) => {
        calls.push(name);
        return impl(...args);
      });
    rec('openSync', () => 3);
    rec('writeSync', () => 8);
    rec('fsyncSync', () => {});
    rec('closeSync', () => {});
    rec('renameSync', () => {});
    rec('unlinkSync', () => {});
  });

  afterEach(() => {
    jest.restoreAllMocks();
  });

  test('order: open → write → fsync → close → rename, then dir fsync (open → fsync → close)', () => {
    atomicWriteFile('/data/x.json', '{"a":1}');
    expect(calls).toEqual([
      'openSync', 'writeSync', 'fsyncSync', 'closeSync', 'renameSync',
      'openSync', 'fsyncSync', 'closeSync',
    ]);
  });

  test('dir fsync opens the PARENT directory (second openSync), not another tmp file', () => {
    atomicWriteFile('/data/x.json', '{}');
    const dirOpen = fs.openSync.mock.calls[1];
    expect(dirOpen[0]).toBe('/data');
    expect(dirOpen[1]).toBe('r');
  });

  test('dir fsync failure is swallowed (write still succeeds)', () => {
    let n = 0;
    fs.fsyncSync.mockImplementation(() => {
      n += 1;
      if (n === 2) throw new Error('EINVAL: invalid argument'); // 2nd fsync = dir
    });
    expect(() => atomicWriteFile('/data/x.json', '{}')).not.toThrow();
    expect(fs.renameSync).toHaveBeenCalled();
  });

  test('open uses exclusive-create with the 0600 default on the tmp path', () => {
    atomicWriteFile('/data/x.json', '{}');
    const [tmpPath, flags, modeArg] = fs.openSync.mock.calls[0];
    expect(tmpPath).toMatch(/^\/data\/\.x\.json\.tmp-/);
    expect(flags).toBe('wx');
    expect(modeArg).toBe(0o600);
  });

  test('write passes the payload with utf8 encoding', () => {
    atomicWriteFile('/data/x.json', '{"a":1}');
    expect(fs.writeSync.mock.calls[0]).toEqual([3, '{"a":1}', null, 'utf8']);
  });

  test('rename swaps a same-dir temp onto the target', () => {
    atomicWriteFile('/data/x.json', '{}');
    const [tmp, dest] = fs.renameSync.mock.calls[0];
    expect(tmp).toMatch(/\/data\/\.x\.json\.tmp-/);
    expect(dest).toBe('/data/x.json');
  });

  test('rename failure unlinks the temp and propagates the error', () => {
    fs.renameSync.mockImplementation(() => {
      calls.push('renameSync');
      throw new Error('EXDEV: cross-device link not permitted');
    });
    expect(() => atomicWriteFile('/data/x.json', '{}')).toThrow(/EXDEV/);
    expect(calls).toEqual([
      'openSync', 'writeSync', 'fsyncSync', 'closeSync', 'renameSync', 'unlinkSync',
    ]);
  });

  test('open failure propagates without write/rename (nothing was created)', () => {
    fs.openSync.mockImplementation(() => {
      calls.push('openSync');
      throw new Error('EACCES: permission denied');
    });
    expect(() => atomicWriteFile('/data/x.json', '{}')).toThrow(/EACCES/);
    // best-effort unlink of the never-created temp, then stop
    expect(calls).toEqual(['openSync', 'unlinkSync']);
  });
});

// DC-100: invite-store migrated off its private _atomicWriteJSON copy onto
// the canonical writer. Store-level pins: writes are durable-canonical
// (0600, complete JSON, no temp leftovers) even under back-to-back mutations
// — the access pattern that could collide tmp names in the naive copy.
describe('DC-100 invite-store on canonical atomic-write (real fs)', () => {
  let dir, store;

  beforeEach(() => {
    dir = fs.mkdtempSync(path.join(os.tmpdir(), 'dc100-invite-'));
    store = require('../src/security/invite-store').createInviteStore({ dataDir: dir });
  });
  afterEach(() => { try { fs.rmSync(dir, { recursive: true, force: true }); } catch (_) {} });

  test('issued invite lands as complete JSON at mode 0600 with no temp leftovers', async () => {
    const r = await store.issue({ email: 'dc100@x.com', ttlMs: 60_000 });
    expect(r.ok).toBe(true);
    const file = path.join(dir, 'invites.json');
    const st = fs.statSync(file);
    expect(st.mode & 0o777).toBe(0o600);
    const data = JSON.parse(fs.readFileSync(file, 'utf8'));
    expect(Object.keys(data.invites)).toHaveLength(1);
    const leftovers = fs.readdirSync(dir).filter((f) => f !== 'invites.json');
    expect(leftovers).toEqual([]);
  });

  test('back-to-back mutations (issue, revoke, issue) never collide on tmp names', async () => {
    const a = await store.issue({ email: 'a@x.com', ttlMs: 60_000 });
    const b = await store.issue({ email: 'b@x.com', ttlMs: 60_000 });
    await store.revoke(a.id);
    const c = await store.issue({ email: 'c@x.com', ttlMs: 60_000 });
    expect(b.ok).toBe(true);
    expect(c.ok).toBe(true);
    const data = JSON.parse(fs.readFileSync(path.join(dir, 'invites.json'), 'utf8'));
    expect(Object.keys(data.invites).sort()).toEqual([b.id, c.id].sort());
    const leftovers = fs.readdirSync(dir).filter((f) => f !== 'invites.json');
    expect(leftovers).toEqual([]);
  });
});