Warn for custom request connectors in legacy mode

Author: simolus3

packages/node/tests/sync.test.ts

@@ -2,6 +2,7 @@ import { beforeEach, describe, expect, vi } from 'vitest';
 
 import {
   CommonPowerSyncDatabase,
+  LogRecord,
   PowerSyncLogger,
   ProgressWithOperations,
   Schema,
@@ -33,6 +34,28 @@ describe('Sync', () => {
   describe('bson', () => defineSyncTests(true));
 
   describe('checkpoint requests', () => {
+    mockSyncServiceTest('warns for custom connectors without requests being enabled', async ({ syncService }) => {
+      const records: LogRecord[] = [];
+
+      const database = await syncService.createDatabase({ logger: { log: records.push.bind(records) } });
+      const connector = new (class extends TestConnector {
+        async postCheckpointRequest(_clientId: string, requestId: string) {
+          return requestId;
+        }
+      })();
+
+      await database.connect(connector);
+      expect(records).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            message: expect.stringContaining(
+              'implements postCheckpointRequest, but connect() was called without checkpoint requests'
+            )
+          })
+        ])
+      );
+    });
+
     mockSyncServiceTest('requests checkpoints for updates', async ({ syncService }) => {
       const database = await syncService.createDatabase();
       await database.connect(new TestConnector(), { checkpointMode: 'requests' });

packages/shared-internals/src/client/BasePowerSyncDatabase.ts

@@ -34,11 +34,7 @@ import {
   SqliteRecord,
   SyncStreamConnectionMethod
 } from '@powersync/common';
-import {
-  BucketStorageAdapter,
-  PSInternalTable,
-  targetCheckpointRequestId
-} from './sync/bucket/BucketStorageAdapter.js';
+import { BucketStorageAdapter, PSInternalTable } from './sync/bucket/BucketStorageAdapter.js';
 import { SyncStatusSnapshot } from '../db/crud/SyncStatus.js';
 import {
   ConnectionManager,

packages/shared-internals/src/client/ConnectionManager.ts

@@ -150,12 +150,21 @@ export class ConnectionManager extends BaseObserver<ConnectionManagerListener> {
     const hadPendingOptions = !!this.pendingConnectionOptions;
 
     // Update pending options to the latest values
+    const resolvedOptions = resolveSyncOptions(options, this.options.defaultConnectionMethod);
     this.pendingConnectionOptions = {
       connector,
-      options: resolveSyncOptions(options, this.options.defaultConnectionMethod),
+      options: resolvedOptions,
       schema: serializedSchema
     };
 
+    if (connector.postCheckpointRequest && resolvedOptions.checkpointMode == 'legacy') {
+      this.logger.log({
+        level: LogLevels.warn,
+        message:
+          'The backend connector implements postCheckpointRequest, but connect() was called without checkpoint requests enabled.'
+      });
+    }
+
     // Disconnecting here provides aborting in progress connection attempts.
     // The connectInternal method will clear pending options once it starts connecting (with the options).
     // We only need to trigger a disconnect here if we have already reached the point of connecting.