fune/browser/components/customizableui/test/browser_open_in_lazy_tab.js

"use strict";

/**
 * Check that customize mode can be loaded in a lazy tab.
 */
add_task(async function open_customize_mode_in_lazy_tab() {
  let tab = BrowserTestUtils.addTab(gBrowser, "about:blank", {
    createLazyBrowser: true,
  });
  gCustomizeMode.setTab(tab);

  is(tab.linkedPanel, "", "Tab should be lazy");

  let tabLoaded = new Promise(resolve => {
    gBrowser.addTabsProgressListener({
      async onLocationChange(aBrowser) {
        if (tab.linkedBrowser == aBrowser) {
          gBrowser.removeTabsProgressListener(this);
          await Promise.resolve();
          resolve();
        }
      },
    });
  });
  let customizePromise = BrowserTestUtils.waitForEvent(
    gNavToolbox,
    "customizationready"
  );
  gCustomizeMode.enter();
  await customizePromise;
  await tabLoaded;

  is(
    tab.getAttribute("customizemode"),
    "true",
    "Tab should be in customize mode"
  );

  let customizationContainer = document.getElementById(
    "customization-container"
  );
  is(
    customizationContainer.hidden,
    false,
    "Customization container should be visible"
  );

  await endCustomizing();
});