Testing with scenarios

A scenario is a JSON file of steps that drives your game in a real browser and checks what happens. Time only moves forward through wait steps, so runs are deterministic.

{
  "$schema": "../node_modules/@debuffjp/cli/schema/scenario.schema.json",
  "steps": [
    { "press": "ArrowRight" },
    { "wait": 30 },
    { "release": "ArrowRight" },
    { "expect": { "state.player.x": { "gt": 200 } } },
    { "set": { "player.speed": 400 } },
    { "capture": "after-move" }
  ]
}

Save it in scenarios/, then run:

npx debuff scenario            # all scenarios
npx debuff scenario --update   # accept new screenshots as baselines

Steps

Step	Effect
{ "wait": n }	Advance n fixed simulation steps
{ "press": code } / { "release": code }	Hold or release a key
{ "tap": [x, y] }	Tap the pointer at logical coordinates
{ "pointerDown" / "pointerMove": [x, y] }, { "pointerUp": true }	Pointer control
{ "set": { "group.key": value } }	Change params
{ "expect": { path: comparison } }	Assert on state: eq, gt, gte, lt, lte, approx
{ "capture": name }	Screenshot compared with the baseline

expect paths read from the dev state: scene, tick, stats.fps, state.* (your scene's inspect()), and plugins.*.

Baselines are stored per operating system, because fonts render differently on each.