You want a very specific operating system configuration every time you test your software. What is a good solution for your testing needs?

Use two laptop computers that would have the unpatched operating system and then configure the laptops to your desired setting every time you have to run a test

Create a snapshot of a virtual machine so that you can revert back to it after the test is complete

Start with a fresh installation of the operating system on your laptop every time you have to test the software

Use a new virtual machine with a fresh install of the operating system and then update it to the desired configurations every time you want to test the software