fix: Make the CrdtDatabase class ephemeral (#82)

test/serverpod_offline_sync_test_server/lib/server.dart

@@ -15,12 +15,7 @@ Future<void> run(List<String> args) async {
     Protocol(),
     Endpoints(),
     authenticationHandler: demoAuthenticationHandler,
-    // TODO: Remove the duplicate [syncTables] argument from here and the
-    // [initializeCrdtSync] call below.
-    databaseInterceptor: (_, inner) => CrdtDatabase(
-      inner,
-      syncTables: demoSyncTables,
-    ),
+    databaseInterceptor: crdtDatabaseInterceptor,
   )..initializeCrdtSync(syncTables: demoSyncTables);
 
   // Start the server.

test/serverpod_offline_sync_test_server/test/integration/server/crdt_database_interceptor_test.dart

@@ -0,0 +1,70 @@
+import 'package:serverpod_offline_sync_server/serverpod_offline_sync_server.dart';
+import 'package:serverpod_offline_sync_test_server/src/generated/protocol.dart'
+    as server;
+import 'package:test/test.dart';
+
+import '../test_tools/serverpod_test_tools.dart';
+
+void main() {
+  final syncTables = [server.Person.t, server.Address.t];
+
+  withServerpod(
+    'Given a Serverpod with CRDT sync initialized,',
+    (sessionBuilder, _) {
+      final session = sessionBuilder.build();
+      session.serverpod.initializeCrdtSync(syncTables: syncTables);
+
+      test(
+        'when the database interceptor wraps a session database, '
+        'then it returns a CRDT-aware database.',
+        () {
+          final wrapped = crdtDatabaseInterceptor(session, session.db);
+          expect(wrapped, isA<CrdtDatabase>());
+        },
+      );
+
+      test(
+        'when the database interceptor wraps an already-wrapped database, '
+        'then it returns the same instance.',
+        () {
+          final wrapped = crdtDatabaseInterceptor(session, session.db);
+          final reWrapped = crdtDatabaseInterceptor(session, wrapped);
+          expect(identical(reWrapped, wrapped), isTrue);
+        },
+      );
+
+      test(
+        'when resolving the CRDT sync for the pod, '
+        'then the configured instance is returned.',
+        () {
+          expect(session.crdt, isNotNull);
+        },
+      );
+    },
+  );
+
+  withServerpod(
+    'Given a Serverpod without CRDT sync initialized,',
+    (sessionBuilder, _) {
+      final session = sessionBuilder.build();
+
+      test(
+        'when the database interceptor wraps a session database, '
+        'then it returns the original database unchanged.',
+        () {
+          final inner = session.db;
+          final result = crdtDatabaseInterceptor(session, inner);
+          expect(identical(result, inner), isTrue);
+        },
+      );
+
+      test(
+        'when resolving the CRDT sync for the pod, '
+        'then a StateError is thrown.',
+        () {
+          expect(() => session.crdt, throwsStateError);
+        },
+      );
+    },
+  );
+}

test/serverpod_offline_sync_test_server/test/integration/sync/sync_flow_test.dart

@@ -165,7 +165,7 @@ void main() {
                   clientToServer.add(event);
                 });
 
-            final serverSubscription = CrdtSync.instance
+            final serverSubscription = rawServerSession.crdt
                 .sync(
                   serverSession,
                   userId: testCrdtUserId,