add_task(async function () { const PAGE = ` `; const url = "data:text/html," + encodeURI(PAGE); await BrowserTestUtils.withNewTab( { gBrowser, url, }, async function (browser) { let popupShownPromise = BrowserTestUtils.waitForSelectPopupShown(window); await BrowserTestUtils.synthesizeMouseAtCenter("select", {}, browser); let popup = await popupShownPromise; EventUtils.sendString("C", window); EventUtils.sendKey("RETURN", window); ok( await TestUtils.waitForCondition(() => { return SpecialPowers.spawn( browser, [], () => content.document.querySelector("select").value ).then(value => value == 3); }), "Unexpected value for select element (expected 3)!" ); } ); });