add_task(async function () {
  let browserLoadedPromise = BrowserTestUtils.browserLoaded(
    gBrowser.selectedBrowser,
    false,
    "about:mozilla"
  );
  window.browserDOMWindow.openURI(
    makeURI("about:mozilla"),
    null,
    Ci.nsIBrowserDOMWindow.OPEN_CURRENTWINDOW,
    null,
    Services.scriptSecurityManager.getSystemPrincipal()
  );
  await browserLoadedPromise;
  is(
    gBrowser.currentURI.spec,
    "about:mozilla",
    "page loads in the current content window"
  );
});