feat: Basic implementation of the OfflineSyncCrdt methods on SQLite3

test/crdt/crdt_last_modified_timestamp_test.dart

@@ -0,0 +1,78 @@
+import 'package:drift/drift.dart' hide isNotNull, isNull;
+import 'package:drift_offline_first/drift_offline_first.dart';
+import 'package:test/test.dart';
+
+import '../utils/crdt_context.dart';
+import '../utils/database.dart';
+
+void main() {
+  group('Given CRDT for an empty database', () {
+    late OfflineSyncCrdt crdt;
+
+    setUp(() async {
+      (crdt, _, _) = database.crdtContext;
+    });
+
+    test(
+        'when getting the last modified timestamp '
+        'then it returns null since the database is empty.', () async {
+      final lastModified = await crdt.getLastModified();
+      expect(lastModified, isNull);
+    });
+  });
+
+  group('Given CRDT for a database with data', () {
+    late OfflineSyncCrdt crdt;
+    late CrdtDatabase crdtDb;
+    late String nodeId;
+    late Hlc createdHlc;
+
+    setUp(() async {
+      await database.managers.todosTable.create(
+        (t) => t(content: 'test', targetDate: Value(DateTime.now())),
+      );
+
+      (crdt, crdtDb, nodeId) = database.crdtContext;
+
+      final allCrdtDataEntries = await crdtDb.managers.crdtDataTable.get();
+      createdHlc = allCrdtDataEntries.first.hlcTimestamp;
+    });
+
+    group('when getting the last modified timestamp', () {
+      test(
+          'without any filters '
+          'then it returns the HLC timestamp of the created data.', () async {
+        final lastModified = await crdt.getLastModified();
+        expect(lastModified, equals(createdHlc));
+      });
+
+      test(
+          'with onlyNodeId set to the nodeId '
+          'then it returns the HLC timestamp of the created data.', () async {
+        final lastModified = await crdt.getLastModified(onlyNodeId: nodeId);
+        expect(lastModified, equals(createdHlc));
+      });
+
+      test(
+          'with onlyNodeId set to a different nodeId '
+          'then it returns null.', () async {
+        final lastModified = await crdt.getLastModified(onlyNodeId: 'other-node');
+        expect(lastModified, isNull);
+      });
+
+      test(
+          'with exceptNodeId set to the nodeId '
+          'then it returns null.', () async {
+        final lastModified = await crdt.getLastModified(exceptNodeId: nodeId);
+        expect(lastModified, isNull);
+      });
+
+      test(
+          'with exceptNodeId set to a different nodeId '
+          'then it returns the HLC timestamp of the created data.', () async {
+        final lastModified = await crdt.getLastModified(exceptNodeId: 'other-node');
+        expect(lastModified, equals(createdHlc));
+      });
+    });
+  });
+}