California gets roads, traffic, and a car to follow

src/test/roadTraffic.test.ts

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+/** Render-layer contract tests that do not require a WebGL context. */
+
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import * as THREE from "three";
+import type { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
+import CALIFORNIA_TRANSPORT from "../transport/california.ts";
+import { createRoadTrafficLayer } from "../engine/roadTraffic.ts";
+import type { World } from "../engine/world.ts";
+
+function fixture() {
+  const world = {
+    project(lat: number, lng: number): [number, number] {
+      return [(lng + 121) * 20, -(lat - 36) * 20];
+    },
+    groundAt(): number {
+      return 0;
+    },
+  } as unknown as World;
+  const camera = new THREE.PerspectiveCamera(42, 16 / 9, 0.1, 2_000);
+  const controls = {
+    target: new THREE.Vector3(),
+    enabled: true,
+  } as unknown as OrbitControls;
+  const layer = createRoadTrafficLayer(world, camera, controls, {
+    pack: CALIFORNIA_TRANSPORT,
+    routeId: "la-sf-us-101",
+    count: 8,
+    seed: 115,
+  });
+  return { layer, camera, controls };
+}
+
+describe("road traffic render layer", () => {
+  it("draws one articulated hero and instanced background parts", () => {
+    const { layer } = fixture();
+    const hero = layer.group.getObjectByName("model-x-hero");
+    assert.ok(hero);
+    assert.equal(hero.scale.x, 0.18);
+    assert.ok(layer.group.children.some((child) => child instanceof THREE.InstancedMesh));
+    assert.equal(layer.hero()?.routeId, "la-sf-us-101");
+    assert.ok(Math.abs(hero.position.y - 0.155) < 1e-9);
+    layer.dispose();
+  });
+
+  it("switches routes and owns the orbit-control handoff while following", () => {
+    const { layer, camera, controls } = fixture();
+    layer.setRoute("la-sf-i-5");
+    assert.equal(layer.routeId(), "la-sf-i-5");
+    assert.equal(layer.hero()?.routeId, "la-sf-i-5");
+
+    layer.setFollowing(true);
+    assert.equal(layer.following(), true);
+    assert.equal(controls.enabled, false);
+    layer.tick(0.1);
+    assert.ok(camera.position.toArray().every(Number.isFinite));
+    assert.ok(controls.target.toArray().every(Number.isFinite));
+
+    layer.setCameraMode("driver");
+    assert.equal(layer.cameraMode(), "driver");
+    layer.tick(1 / 60);
+    assert.ok(camera.position.y > layer.group.getObjectByName("model-x-hero")!.position.y);
+
+    layer.setFollowing(false);
+    assert.equal(controls.enabled, true);
+    layer.dispose();
+  });
+
+  it("hands manual input to the deterministic hero and resumes assistance", () => {
+    const { layer } = fixture();
+    for (let index = 0; index < 20; index += 1) {
+      layer.setVehicleActions({ throttle: 1, steering: 0.8 });
+      layer.tick(1 / 30);
+    }
+    assert.equal(layer.hero().mode, "manual");
+    assert.ok(layer.hero().lateralOffsetM > 0);
+
+    layer.setVehicleActions({ modeRequest: "assisted" });
+    layer.tick(1 / 30);
+    assert.equal(layer.hero().mode, "assisted");
+    layer.dispose();
+  });
+});