Test domLoaded returns a Promise

test/types.js

@@ -4,3 +4,7 @@ import domLoaded from '../';
 test('domLoaded is a function', t => {
 	t.is(typeof domLoaded, 'function');
 });
+
+test('domLoaded returns a Promise', t => {
+	t.true(domLoaded() instanceof Promise);
+});