polyfill-service/polyfills/document.visibilityState/tests.js

A polyfill combinator

it('has a hidden property', function () {
	expect(typeof document.hidden).not.to.equal('undefined')
});

it('has a visibilityState property', function () {
	expect(typeof document.visibilityState).not.to.equal('undefined')
});

// Because some browsers will have unprefixed native support but will still support the prefixed version, this test will detect a prefix, and fire the event, but the polyfill isn't there so the prefixed version isn't re-fired as the unprefixed one. Therefore this test usefully tests that the polyfill works but can't be used because it will fail in a compliant native implementation. We really need to be able to programmatically trigger a change in page visibility, but I don't believe that's possible.
it.skip('fires a normalized event name', function (done) {
	var prefix = document.mozVisibilityState ? 'moz' : document.webkitVisibilityState ? 'webkit' : null;
	if (!prefix) {
		return done();
	}
	document.addEventListener('visibilitychange', function (ev) {
		expect('normalized event fired').to.equal('normalized event fired');
		done();
	});

	document.dispatchEvent(new Event(prefix + 'visibilitychange'));
	done(new Error('Event not fired'))
});