Ideally I would like test this by having my browser rename a file on my desktop.
Yes, you can do this, this link details some of the available functionality:
Just remember, it's not supported in the major browsers yet, and it's likely when it is many of your visitors will not upgrade for quite some time.
No, as this would be a security vulnerability. As pointed out there are sandboxed file systems, or local database storage in HTML5, but not access to the whole file system.
You could achieve it with a certified Java applet, if you really wanted to achieve it through the browser. To be honest the browser is not the best place to be trying such things.
©2020 All rights reserved.