Playwright E2E

Check that your form works in a real browser, with and without JavaScript. This recipe uses Playwright 1.56.0 and Chromium.

Start the fixture and wait for readiness

import { defineConfig } from "@playwright/test";
import { fileURLToPath } from "node:url";

export default defineConfig({
  testDir: "./e2e",
  fullyParallel: false,
  workers: 1,
  use: { baseURL: "http://127.0.0.1:3107" },
  webServer: {
    command: "node --import tsx docs/samples/island/start.ts",
    cwd: fileURLToPath(new URL("../..", import.meta.url)),
    url: "http://127.0.0.1:3107",
    reuseExistingServer: false,
  },
});

This bounded fixture uses port 3107 and refuses to reuse an unrelated server. The HTTP unit tests use ephemeral ports; Playwright's fixture has a configured origin so the browser can navigate predictably.

Exercise both experiences

import { test, expect } from "@playwright/test";

test("Svelte counter enhances the native form", async ({ page }) => {
  await page.goto("/");
  await expect(page.locator("#note-counter")).toContainText("0 / 200 characters");
  await page.getByLabel("Note", { exact: true }).fill("Hello island");
  await expect(page.locator("#note-counter")).toContainText("12 / 200 characters");
  await page.getByRole("button", { name: "Save note" }).click();
  await expect(page.locator("main > ul")).toContainText("Hello island");
});

test("native submission and retained errors work with JavaScript disabled", async ({
  browser,
  baseURL,
}) => {
  const context = await browser.newContext({ javaScriptEnabled: false, baseURL });
  try {
    const page = await context.newPage();
    await page.goto("/");
    await page.getByLabel("Note", { exact: true }).fill("   ");
    const invalid = page.waitForResponse(
      (response) => response.url().endsWith("/notes") && response.request().method() === "POST",
    );
    await page.getByRole("button", { name: "Save note" }).click();
    expect((await invalid).status()).toBe(422);
    await expect(page.getByRole("alert")).toContainText("Write between 1 and 200 characters");
    await expect(page.getByLabel("Note", { exact: true })).toHaveValue("   ");
    await page.getByLabel("Note", { exact: true }).fill("No JavaScript needed");
    await page.getByRole("button", { name: "Save note" }).click();
    await expect(page.locator("main > ul")).toContainText("No JavaScript needed");
  } finally {
    await context.close();
  }
});

Label/role locators exercise the accessible control markup. The no-JS test checks the actual 422 response and retained value, not just the presence of a button.

npm run build:packages
npm run docs:check
npx playwright install chromium
npm run docs:e2e

On Linux CI, install browser system libraries with npx playwright install --with-deps chromium; .github/workflows/docs.yml does this before running the same tests.

Test hosted sign-in separately with a configured provider.