feat(sync): RN-1680: Sync tests #6597

chris-bes · 2026-01-05T07:53:04Z

Changes:

Sync tests

gemini-code-assist · 2026-01-05T07:53:31Z

Summary of Changes

Hello @chris-bes, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the synchronization capabilities by introducing a dedicated SyncLookup model for better data tracking and refining the SyncSession management with improved state transitions and error handling. A major focus has been placed on bolstering test coverage for the CentralSyncManager, ensuring robustness across pull, push, and session operations, and introducing new test utilities to facilitate more complex testing scenarios. Configuration adjustments, such as enabling avoidRepull by default, aim to optimize sync performance.

Highlights

New SyncLookup Model: Introduced a new SyncLookup model and its corresponding record to manage synchronization lookup data within the database, enhancing the tracking of sync-related information.
Enhanced SyncSession Management: The SyncSessionModel now includes a markAsStartedAt method, allowing for more precise tracking of when a sync session officially begins. Error handling for sync sessions has also been refined with a new helper function errorMessageFromSessionId.
Comprehensive Sync Test Coverage: Added extensive test files for CentralSyncManager covering critical synchronization functionalities such as pull operations (including concurrent transactions), push operations, session lifecycle management (start, connect, end), and SyncLookup table updates. An old example test file was removed.
Test Utility Improvements: New test utilities like setupTestApp, waitForSession, and waitForPushComplete have been added to streamline testing of sync processes. A pauseSnapshotProcess hook was introduced in snapshotOutgoingChanges specifically for testing concurrent snapshot scenarios.
Configuration Update: The default configuration for CentralSyncManager now sets avoidRepull to true, which can optimize sync performance by preventing unnecessary re-pulls of data for devices.
Test Script Refinement: A new package:test:serial script was added to package.json for running Jest tests in serial mode, and the packages/sync-server's test script was updated to utilize this for more controlled test execution.

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Code Review

This pull request introduces a comprehensive suite of tests for the sync functionality, significantly improving the robustness of the CentralSyncManager. The new tests cover pull, push, session management, and the sync lookup table logic, which is a valuable addition. The changes also include minor refactorings and additions to support this testing effort, such as a test hook for pausing snapshots and enabling the avoidRepull feature by default. My review focuses on enhancing type safety within the new test files by replacing the use of any with more specific types, which will improve maintainability and code clarity.

packages/sync-server/src/__tests__/CentralSyncManager.pull.test.ts

gemini-code-assist · 2026-01-05T07:55:42Z

packages/sync-server/src/__tests__/CentralSyncManager.push.test.ts

+import { waitForPushComplete, waitForSession } from '../testUtilities/waitForSync';
+
+describe('CentralSyncManager.push', () => {
+  let models: any;


To improve type safety, please avoid using any. You can type models as TestSyncServerModelRegistry by importing it from ../types.

Suggested change

let models: any;

let models: TestSyncServerModelRegistry;

packages/sync-server/src/__tests__/CentralSyncManager.push.test.ts

packages/sync-server/src/__tests__/CentralSyncManager.session.test.ts

packages/sync-server/src/__tests__/CentralSyncManager.syncLookup.test.ts

jaskfla

Buncha small optional details, but nothing to complain about. Looking great overall—happy for you to pick and choose which comments need addressing and merge without re-review ✅

Thanks for sorting this out 🙏

jaskfla · 2026-01-05T21:58:40Z

packages/database/src/core/modelClasses/SyncSession.js

+   * @param {number} tick
+   */
+  async markAsStartedAt(id, tick) {
+    await this.updateById(id, { started_at_tick: tick });


Small stylistic thing, but could be nice to be explicit that we’re throwing away the return value

Suggested change

await this.updateById(id, { started_at_tick: tick });

void (await this.updateById(id, { started_at_tick: tick }));

jaskfla · 2026-01-05T22:00:28Z

packages/sync-server/package.json

    "start-verbose": "LOG_LEVEL=debug yarn run start-dev",
    "setup-test": "yarn workspace @tupaia/database run setup-test-database",
-    "test": "yarn run package:test"
+    "test": "yarn run package:test:serial"


This is the only usage of :serial, right? Maybe clearer just to call jest --runInBand here?

I’ve had a quick squiz and it seems like the --maxWorkers=50% we set in the global script is Jest’s default anyway

Simpler to just remove --maxWorkers=50% from the global script. Here, call yarn run package:test --runInBand and let Yarn forward the argument

jaskfla · 2026-01-05T22:01:31Z

packages/sync-server/src/__tests__/CentralSyncManager.pull.test.ts

+const POLICY = {
+  DL: [BES_ADMIN_PERMISSION_GROUP, 'Admin'],
+  KI: [TUPAIA_ADMIN_PANEL_PERMISSION_GROUP, 'Admin'],
+};


Suggested change

const POLICY = {

DL: [BES_ADMIN_PERMISSION_GROUP, 'Admin'],

KI: [TUPAIA_ADMIN_PANEL_PERMISSION_GROUP, 'Admin'],

};

const POLICY = {

DL: [BES_ADMIN_PERMISSION_GROUP, 'Admin'],

KI: [TUPAIA_ADMIN_PANEL_PERMISSION_GROUP, 'Admin'],

} as const;

Ditto with SYNC_CONFIG in CentralSyncManager.syncLookup.test.ts

jaskfla · 2026-01-05T22:02:55Z

packages/sync-server/src/__tests__/CentralSyncManager.pull.test.ts

+      );
+    });
+
+    it("excludes inserted records from another sync session when the current' session's snapshot transaction already started", async () => {


Suggested change

it("excludes inserted records from another sync session when the current' session's snapshot transaction already started", async () => {

it('excludes inserted records from another sync session when the current session’s snapshot transaction already started', async () => {

jaskfla · 2026-01-05T22:05:56Z

packages/sync-server/src/__tests__/CentralSyncManager.pull.test.ts

+          recordId: userAccount4.id,
+          data: await userAccount4.getData(),
+        },
+      ] as SyncSnapshotAttributes[];


Slightly dangerous cast? Looks like the array elements are missing a couple properties that SyncSnapshotAttributes requires

Happy to overlook this in test environment, though—your call 🙂

jaskfla · 2026-01-05T22:13:33Z

packages/sync-server/src/__tests__/CentralSyncManager.session.test.ts

+
+  describe('startSession', () => {
+    it('creates a new session', async () => {
+      const centralSyncManager = new CentralSyncManager(models);


Optional: could declare let centralSyncManager: CentralSyncManager in a higher scope and do centralSyncManager = new CentralSyncManager(models) in the beforeEach phase

jaskfla · 2026-01-05T22:24:18Z

packages/sync-server/src/__tests__/CentralSyncManager.syncLookup.test.ts

+          record_id: expect.anything(),
+          record_type: model.databaseRecord,
+          project_ids: expect.anything(),


Worth being stricter here?

Suggested change

record_id: expect.anything(),

record_type: model.databaseRecord,

project_ids: expect.anything(),

record_id: expect.stringMatcing(/^[a-f\d]{24}$/),

record_type: model.databaseRecord,

project_ids: expect.arrayOf(expect.stringMatching(/^[a-f\d]{24}$/));

expect.any(String) also works as a middle ground, but matching the pattern feels right there

(.anything() appears a few times in this test suite, but I won’t repeat this comment)

jaskfla · 2026-01-05T22:30:38Z

packages/sync-server/src/sync/CentralSyncManager.ts

  lookupTable: {
    perModelUpdateTimeoutMs: 1_000_000,
-    avoidRepull: false,
+    avoidRepull: true,


Double checking this was an intentional change?

jaskfla · 2026-01-05T22:37:38Z

packages/sync-server/src/testUtilities/setupTest.ts

+// @ts-expect-error - central-server createApp is a JS file without types
+import { createApp } from '../../../central-server/src/createApp';
+
+const models = getTestModels() as ModelRegistry & { user: any };


Suggested change

const models = getTestModels() as ModelRegistry & { user: any };

const models = getTestModels() as SyncServerModelRegistry;

(Remember to update imports)

jaskfla · 2026-01-05T22:44:01Z

packages/sync-server/src/testUtilities/waitForSync.ts

+  let ready = false;
+  while (!ready) {
+    ready = await centralSyncManager.checkSessionReady(sessionId);
+    await sleep(100);
+  }


One of those rare instances where do…while makes sense!

Honestly not fussed about changing; I like the readability of the ready variable. This is mostly just a reminder that do loops exist in JS 😆

Suggested change

let ready = false;

while (!ready) {

ready = await centralSyncManager.checkSessionReady(sessionId);

await sleep(100);

}

do {

await sleep(100);

} while (!(await centralSyncManager.checkSessionReady(sessionId)))

cursor · 2026-01-06T04:29:22Z

packages/sync-server/src/__tests__/CentralSyncManager.syncLookup.test.ts

+        record_type: 'user_account',
+        updated_at_sync_tick: expectedTick.toString(),
+      });
+    });


Test assertion never validates record data

The forEach callback doesn't receive any parameters (uses () instead of (record)), and expect.objectContaining({...}) by itself creates a matcher but never actually asserts anything. The matcher needs to be used with expect(record).toEqual(...) or similar. This test will always pass regardless of the actual data in userAccountLookupData, effectively making it useless for verifying the updated_at_sync_tick values.

cursor · 2026-01-06T04:29:22Z

packages/sync-server/src/__tests__/CentralSyncManager.session.test.ts

+
+      await centralSyncManager.connectToSession(sessionId);
+
+      expect(() => centralSyncManager.connectToSession(sessionId)).not.toThrow();


Test uses synchronous assertion on async function

The test uses expect(() => connectToSession(...)).not.toThrow() on an async function, but .toThrow() only catches synchronous throws, not Promise rejections. Since connectToSession is async, this assertion will always pass even if the function returns a rejected Promise. The correct pattern is await expect(...).resolves.toBeDefined() as used elsewhere (e.g., line 189 uses the async-aware .rejects.toThrow()).

cursor · 2026-01-06T04:29:22Z

packages/sync-server/src/sync/CentralSyncManager.ts

  lookupTable: {
    perModelUpdateTimeoutMs: 1_000_000,
-    avoidRepull: false,
+    avoidRepull: true,


Default config change in test-focused PR

The default value for avoidRepull in DEFAULT_CONFIG was changed from false to true. This changes production behavior in a PR that's titled as "Sync tests" and should only be adding tests. A reviewer in the discussion explicitly asked "Double checking this was an intentional change?" suggesting this may have been accidentally included. This behavioral change affects how sync data is handled for devices and could impact production sync behavior if not intentional.

# Conflicts: # packages/sync/src/utils/index.ts

packages/sync-server/src/__tests__/CentralSyncManager.session.test.ts

added tests

ecf85cd

gemini-code-assist bot reviewed Jan 5, 2026

View reviewed changes

clean up

53db737

jaskfla approved these changes Jan 5, 2026

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jaskfla force-pushed the rn-1717-test-four branch from 55e4843 to 2600161 Compare January 5, 2026 22:55

Merge branch 'rn-1717-test-four' into rn-1680-sync-tests

95e61e7

cursor bot reviewed Jan 6, 2026

View reviewed changes

jaskfla added 9 commits January 20, 2026 13:49

Merge branch 'rn-1717-test-four' into rn-1680-sync-tests

746d106

# Conflicts: # packages/sync/src/utils/index.ts

Merge branch 'rn-1717-test-four' into rn-1680-sync-tests

eb4a87e

fix bad type hint

e5685d6

fix bad merge resolution

b5ac8e7

use const

113b9dc

fix straggling bad usage

4c92873

fix dangerous accesses

7828579

fix more straggling bad usages

fc30487

fix unsafe access

b1f96ab

jaskfla reviewed Feb 9, 2026

View reviewed changes

packages/sync-server/src/__tests__/CentralSyncManager.session.test.ts Outdated Show resolved Hide resolved

fix always-passing assertions

e0923b6

	await this.updateById(id, { started_at_tick: tick });
	void (await this.updateById(id, { started_at_tick: tick }));

	it("excludes inserted records from another sync session when the current' session's snapshot transaction already started", async () => {
	it('excludes inserted records from another sync session when the current session’s snapshot transaction already started', async () => {

	const models = getTestModels() as ModelRegistry & { user: any };
	const models = getTestModels() as SyncServerModelRegistry;


		await centralSyncManager.connectToSession(sessionId);

		expect(() => centralSyncManager.connectToSession(sessionId)).not.toThrow();

feat(sync): RN-1680: Sync tests #6597

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chris-bes commented Jan 5, 2026

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Test assertion never validates record data

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Test uses synchronous assertion on async function

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Default config change in test-focused PR

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