Updated the test system

test/URLJoin.test.js

@@ -0,0 +1,16 @@
+const expect = require('expect');
+const {URLJoin} = require('./_30s.js');
+
+test('URLJoin is a Function', () => {
+  expect(URLJoin).toBeInstanceOf(Function);
+});
+test('Returns proper URL', () => {
+  expect(URLJoin('http://www.google.com', 'a', '/b/cd', '?foo=123', '?bar=foo')).toBe(
+    'http://www.google.com/a/b/cd?foo=123&bar=foo'
+  );
+});
+test('Returns proper URL', () => {
+  expect(URLJoin('file://www.google.com', 'a', '/b/cd', '?foo=123', '?bar=foo')).toBe(
+    'file:///www.google.com/a/b/cd?foo=123&bar=foo'
+  );
+});