gecko-dev/toolkit/components/extensions/test/xpcshell/test_ext_shadowdom.js

"use strict";

// ExtensionContent.sys.mjs needs to know when it's running from xpcshell,
// to use the right timeout for content scripts executed at document_idle.
ExtensionTestUtils.mockAppInfo();

const server = createHttpServer();
server.registerDirectory("/data/", do_get_file("data"));

const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;

add_task(async function test_contentscript_shadowDOM() {
  function backgroundScript() {
    browser.test.assertTrue(
      "openOrClosedShadowRoot" in document.documentElement,
      "Should have openOrClosedShadowRoot in Element in background script."
    );
  }

  function contentScript() {
    let host = document.getElementById("host");
    browser.test.assertTrue(
      "openOrClosedShadowRoot" in host,
      "Should have openOrClosedShadowRoot in Element."
    );
    let shadowRoot = host.openOrClosedShadowRoot;
    browser.test.assertEq(
      shadowRoot.mode,
      "closed",
      "Should have closed ShadowRoot."
    );
    browser.test.sendMessage("contentScript");
  }

  let extension = ExtensionTestUtils.loadExtension({
    manifest: {
      content_scripts: [
        {
          matches: ["http://*/*/file_shadowdom.html"],
          js: ["content_script.js"],
        },
      ],
    },
    background: backgroundScript,
    files: {
      "content_script.js": contentScript,
    },
  });

  await extension.startup();

  let contentPage = await ExtensionTestUtils.loadContentPage(
    `${BASE_URL}/file_shadowdom.html`
  );
  await extension.awaitMessage("contentScript");

  await contentPage.close();
  await extension.unload();
});