test: add download zip flow

web/e2e/helpers/page.ts

@@ -1,4 +1,9 @@
-import { expect, type Locator, type Page } from "playwright/test";
+import {
+	expect,
+	type Download,
+	type Locator,
+	type Page,
+} from "playwright/test";
 import type { SourceFile } from "./fixtures";
 
 export const TEST_IDS = {
@@ -73,14 +78,18 @@ export async function uploadImage(page: Page, file: SourceFile): Promise<void> {
 	});
 }
 
-export async function downloadResult(page: Page): Promise<string> {
+export async function downloadResultFile(page: Page): Promise<Download> {
 	const button = page.getByRole("button", { name: "Download result" });
 	await expect(button).toBeVisible();
 	const [download] = await Promise.all([
 		page.waitForEvent("download"),
 		button.click(),
 	]);
-	return download.suggestedFilename();
+	return download;
+}
+
+export async function downloadResult(page: Page): Promise<string> {
+	return (await downloadResultFile(page)).suggestedFilename();
 }
 
 export async function expectNoErrorAlert(page: Page): Promise<void> {

web/e2e/pipeline.spec.ts

@@ -1,3 +1,5 @@
+import { readFile } from "node:fs/promises";
+import { unzipSync } from "fflate";
 import { expect, test } from "playwright/test";
 import {
 	corruptPng,
@@ -8,6 +10,7 @@ import {
 } from "./helpers/fixtures";
 import {
 	downloadResult,
+	downloadResultFile,
 	errorAlert,
 	expectNoErrorAlert,
 	expectNoErrors,
@@ -89,6 +92,39 @@ test("reset restores defaults and re-runs with the source", async ({
 	expectNoErrors(sink);
 });
 
+test("split-into-parts-png downloads a zip with named PNG parts", async ({
+	page,
+}) => {
+	const sink = trackErrors(page);
+	await openTool(page, "split-into-parts-png");
+	await uploadImage(page, landscapePng);
+	await rangeInput(page, "Columns").fill("3");
+	await rangeInput(page, "Rows").fill("2");
+	await expect(page.getByText("part-1-3.png")).toBeVisible();
+
+	const download = await downloadResultFile(page);
+	expect(download.suggestedFilename()).toBe("split-into-parts-png.zip");
+	const path = await download.path();
+	if (!path) throw new Error("download path is unavailable");
+	const entries = unzipSync(new Uint8Array(await readFile(path)));
+
+	expect(Object.keys(entries)).toEqual([
+		"part-1-1.png",
+		"part-1-2.png",
+		"part-1-3.png",
+		"part-2-1.png",
+		"part-2-2.png",
+		"part-2-3.png",
+	]);
+	for (const bytes of Object.values(entries)) {
+		expect(Array.from(bytes.subarray(0, 8))).toEqual([
+			137, 80, 78, 71, 13, 10, 26, 10,
+		]);
+	}
+	await expectNoErrorAlert(page);
+	expectNoErrors(sink);
+});
+
 test("blur: changing slider updates result image", async ({ page }) => {
 	await openTool(page, "blur-png");
 	await uploadImage(page, opaquePng);