Updated the test system

test/delay.test.js

@@ -0,0 +1,15 @@
+const expect = require('expect');
+const {delay} = require('./_30s.js');
+
+test('delay is a Function', () => {
+  expect(delay).toBeInstanceOf(Function);
+});
+test('Works as expecting, passing arguments properly', () => {
+  delay(
+    function(text) {
+      expect(text).toBe('test');
+    },
+    1000,
+    'test'
+  );
+});