Chrome Extensions

note

Extensions only work in Chrome / Chromium in non-headless mode, launched with a persistent context.

The following is code for getting a handle to the background page of a Manifest v2 extension whose source is located in ./my-extension:

const { chromium } = require('playwright');

(async () => {
  const pathToExtension = require('path').join(__dirname, 'my-extension');
  const userDataDir = '/tmp/test-user-data-dir';
  const browserContext = await chromium.launchPersistentContext(userDataDir,{
    headless: false,
    args: [
      `--disable-extensions-except=${pathToExtension}`,
      `--load-extension=${pathToExtension}`
    ]
  });
  let [backgroundPage] = browserContext.backgroundPages();
  if (!backgroundPage)
    backgroundPage = await browserContext.waitForEvent('backgroundpage');

  // Test the background page as you would any other page.
  await browserContext.close();
})();

Testing

To have the extension loaded when running tests you can use a test fixture to set the context. You can also dynamically retrieve the extension id and use it to load and test the popup page for example.

import { test as base, expect, BrowserContext } from "@playwright/test";
import path from "path";

export const test = base.extend<{
  context: BrowserContext;
  extensionId: string;
}>({
  context: async ({ }, use) => {
    const pathToExtension = path.join(__dirname, "my-extension");
    const context = await chromium.launchPersistentContext("", {
      headless: false,
      args: [
        `--disable-extensions-except=${pathToExtension}`,
        `--load-extension=${pathToExtension}`,
      ],
    });
    await use(context);
    await context.close();
  },
  extensionId: async ({ context }, use) => {
    /*
    // for manifest v2:
    let [background] = context.backgroundPages()
    if (!background)
      background = await context.waitForEvent("backgroundpage")
    */

    // for manifest v3:
    let [background] = context.serviceWorkers();
    if (!background)
      background = await context.waitForEvent("serviceworker");

    const extensionId = background.url().split("/")[2];
    await use(extensionId);
  },
});

test("example test", async ({ page }) => {
  await page.goto("https://example.com");
  await expect(page.locator("body")).toHaveText("Changed by my-extension");
});

test("popup page", async ({ page, extensionId }) => {
  await page.goto(`chrome-extension://${extensionId}/popup.html`);
  await expect(page.locator("body")).toHaveText("my-extension popup");
});

Testing​

Testing