Test persisting/removing data based on write checkpoints.

Author: rkistner

packages/powersync_core/test/connected_test.dart

@@ -44,6 +44,7 @@ void main() {
           await testUtils.testFactory(path: path),
           schema: defaultSchema,
           maxReaders: 3);
+      addTearDown(() => {db.close()});
       await db.initialize();
 
       final connectedCompleter = Completer();
@@ -83,6 +84,9 @@ void main() {
           await testUtils.testFactory(path: path),
           schema: defaultSchema,
           maxReaders: 3);
+      // Shorter retry delay, to speed up tests
+      db.retryDelay = Duration(milliseconds: 10);
+      addTearDown(() => {db.close()});
       await db.initialize();
 
       // Create an item which should trigger an upload.
@@ -132,5 +136,111 @@ void main() {
 
       await db.disconnect();
     });
+
+    test('should persist local changes when there is no write checkpoint',
+        () async {
+      final testServer = await createTestServer();
+      final connector = TestConnector(() async {
+        return PowerSyncCredentials(
+            endpoint: testServer.uri.toString(),
+            token: 'token not used here',
+            expiresAt: DateTime.now());
+      }, uploadData: (database) async {
+        final tx = await database.getNextCrudTransaction();
+        if (tx != null) {
+          await tx.complete();
+        }
+      });
+
+      final db = PowerSyncDatabase.withFactory(
+          await testUtils.testFactory(path: path),
+          schema: defaultSchema,
+          maxReaders: 3);
+      addTearDown(() => {db.close()});
+      await db.initialize();
+
+      // Create an item which should trigger an upload.
+      await db.execute(
+          'INSERT INTO customers (id, name) VALUES (uuid(), ?)', ['steven']);
+
+      // Manually simulate upload before connecting.
+      // This is simpler than doing this via connect() and waiting for it to complete.
+      await connector.uploadData(db);
+
+      // Check that the data is present locally
+      expect(
+          await db.getAll('select name from customers'),
+          equals([
+            {'name': 'steven'}
+          ]));
+
+      // Connect and send a checkpoint back, but no write checkpoint.
+      testServer
+          .addEvent('{"checkpoint": {"last_op_id": "10", "buckets": []}}\n');
+      testServer.addEvent('{"checkpoint_complete": {"last_op_id": "10"}}\n');
+
+      // Now connect and wait for sync to complete
+      await db.connect(connector: connector);
+      await db.statusStream
+          .firstWhere((status) => status.connected && status.downloading);
+      await Future.delayed(Duration(milliseconds: 20));
+      expect(
+          await db.getAll('select name from customers'),
+          equals([
+            {'name': 'steven'}
+          ]));
+    });
+
+    test('should remove local changes when there a write checkpoint', () async {
+      // The only difference between this and the one above, is that the synced
+      // checkpoint here contains a write checkpoint, matching the write-checkpoint2.json
+      // API. This will trigger the local changes to be removed.
+      final testServer = await createTestServer();
+      final connector = TestConnector(() async {
+        return PowerSyncCredentials(
+            endpoint: testServer.uri.toString(),
+            token: 'token not used here',
+            expiresAt: DateTime.now());
+      }, uploadData: (database) async {
+        final tx = await database.getNextCrudTransaction();
+        if (tx != null) {
+          await tx.complete();
+        }
+      });
+
+      final db = PowerSyncDatabase.withFactory(
+          await testUtils.testFactory(path: path),
+          schema: defaultSchema,
+          maxReaders: 3);
+      addTearDown(() => {db.close()});
+      await db.initialize();
+
+      // Create an item which should trigger an upload.
+      await db.execute(
+          'INSERT INTO customers (id, name) VALUES (uuid(), ?)', ['steven']);
+
+      // Manually simulate upload before connecting.
+      // This is simpler than doing this via connect() and waiting for it to complete.
+      await connector.uploadData(db);
+
+      // Check that the data is present locally
+      expect(
+          await db.getAll('select name from customers'),
+          equals([
+            {'name': 'steven'}
+          ]));
+
+      // Connect and send a checkpoint back, but no write checkpoint.
+      testServer.addEvent(
+          '{"checkpoint": {"last_op_id": "10", "buckets": [], "write_checkpoint": "10"}}\n');
+      testServer.addEvent('{"checkpoint_complete": {"last_op_id": "10"}}\n');
+
+      // Now connect and wait for sync to complete
+      await db.connect(connector: connector);
+      await db.statusStream
+          .firstWhere((status) => status.connected && status.downloading);
+      await Future.delayed(Duration(milliseconds: 20));
+      expect(await db.getAll('select name from customers'), equals([]));
+    });
   });
 }

packages/powersync_core/test/server/sync_server/mock_sync_server.dart

@@ -28,6 +28,11 @@ class TestHttpServerHelper {
             context: {
               "shelf.io.buffer_output": false
             });
+      })
+      ..get('/write-checkpoint2.json', (request) {
+        return Response.ok('{"data": {"write_checkpoint": "10"}}', headers: {
+          'Content-Type': 'application/json',
+        });
       });
 
     _server = await io.serve(router.call, 'localhost', 0);