Piecemeal is a small Dart library of low-level utility types aimed at 2D games. In particular, I harvested it from my roguelike Hauberk.
Add it to your package's pubspec:
dependencies:
piecemeal: any
Import it:
import 'package:piecemeal/piecemeal.dart';
Piecemeal comes with a unit test suite. From the root directory of piecemeal, run:
dart --checked test/run_all.dart