Unit tests in dart

To run flutter or dart test with the bridge you need to load the library on your own development machine (Windows/MacOS/Linux/CI). For that use loadLibForFlutter or loadLibForDart, for example:

BridgeImpl initializeExternalLibrary(String path) => BridgeImpl(loadLibForDart(path));

Note however, that you need to build the library for your IDE's Operating System. cargo build should normally handle that.

Do not change the target to your OS only, as otherwise you will not be able to build for your target platform anymore.

Example setup (verified on MacOS)

|- lib
|- test
|-- ffi.test.dart
|-- bridge_test.dart
|- rust
|-- src
|--- api.rs
|-- target

Where ffi.test.dart has the following content:

import 'package:basis_hybrid/bridge_generated.dart';
import 'package:flutter_rust_bridge/flutter_rust_bridge.dart';

BridgeImpl initializeExternalLibrary(String path) {
  return BridgeImpl(

and then bridge_test.dart has the following content:

import 'package:basis_hybrid/bridge_definitions.dart';
import 'package:flutter_test/flutter_test.dart';

import 'ffi.test.dart';

Future<void> main() async {
  final api = initializeExternalLibrary('rust/target/debug/librustbridge.dylib');
  await api.init(sqlPath: 'test.db', kvPath: 'test.kv');

  test('User save/load', () async {
     await api.saveUser();
     var user = await api.readUser();
     expect(user, isNotNull);

Ensure that you have your IDE's system target installed (rustup) according to Creating a new project, after running cargo build you should've a library in rust/target/debug/