Test Harness

import { harness, type Harness, type HarnessOpts } from "@f0rbit/forge";

const h: Harness = harness({
  seed: 1,
  fixed_dt: 1/60,
  bindings: presets.movement_2d,
  __dev__: true,
});

Returns:

type Harness = {
  world: World;
  schedule: Schedule;
  time: Time;
  rng: Rng;
  res: Resources;
  input: Input;
  debug: Debug;
  palette: Palette;
  ctx: Ctx;
  tick: (real_dt?: number) => void;
};

harness.tick(real_dt?) advances time, runs the update stage, and drains the debug frame. Use h.schedule.tick(h.world, h.ctx) to pump every stage (including pre / post / render) — harness.tick is the minimal “just run game logic” path.

Use cases

• Unit-test a single system. Spawn entities, call the system directly: my_system(h.world, h.ctx).
• Integration-test a plugin. Install via game_plugin(h.world, h.schedule), drive with h.input.inject_actions(...), advance ticks.
• Replay-driven test. Wire replay.play(doc, h.input, () => h.time.tick) and tick to completion. (See determinism section.)

__dev__ controls whether debug is the real debug({ enabled: true, dev: true }) instance or debug_noop(). Default true. Pass false for production-mode testing.

The harness omits engine_store from its ctx — wire one up yourself if your tests need persistence:

const h = harness();
const store = engine_store();
const ctx = { ...h.ctx, store };
sys(h.world, ctx);