If you are in developer mode and after you cache is cleaned , then after loading you specific page you will see your test.js file in page source. Now the same result we can achieve using following XML update.
Update 1 : Using <script /> Node.
Update 2 : Using <css /> Node.
Both these changes will assert test.js into your page source. Wait .. did <css /> node worked to add a js file ? The answer is Yes. You can interchangably use any of <link />, <script /> or <css /> in order to add a js or css file.
ie, you can use <script /> node in order to add a CSS file and you can use <css /> node in order to add a JS file, which may arise confusion among developers.
What is your opinion regarding this ? Please let me know through comment section.