Adjust tests to use vitest + jsdom

engine/lib/loadImage.test.ts

@@ -0,0 +1,55 @@
+import { afterEach, beforeEach, expect, test } from "vitest";
+import { loadImage } from "./loadImage.ts";
+
+class MockImage {
+	static instances: MockImage[] = [];
+
+	onload: (() => void) | null = null;
+	onerror: ((error: unknown) => void) | null = null;
+	src = "";
+
+	constructor() {
+		MockImage.instances.push(this);
+	}
+}
+
+const RealImage = globalThis.Image;
+const realError = console.error;
+const errors: unknown[][] = [];
+
+beforeEach(() => {
+	globalThis.Image = MockImage as unknown as typeof Image;
+	console.error = (...args: unknown[]) => {
+		errors.push(args);
+	};
+});
+
+afterEach(() => {
+	globalThis.Image = RealImage;
+	console.error = realError;
+	MockImage.instances = [];
+	errors.length = 0;
+});
+
+test("loadImage", async () => {
+	const promise = loadImage("image.png");
+	const image = MockImage.instances[0];
+
+	expect(image.src).toBe("image.png");
+
+	image.onload!();
+
+	await expect(promise).resolves.toBe(image);
+	expect(errors).toEqual([]);
+});
+
+test("loadImage error", async () => {
+	const promise = loadImage("missing.png");
+	const image = MockImage.instances[0];
+
+	image.onerror!("missing");
+
+	// errors are logged, but the promise still resolves with the image
+	await expect(promise).resolves.toBe(image);
+	expect(errors).toEqual([["missing"]]);
+});