Why you shouldn't run your software tests on your computer
It might sound convenient to run your automated software tests on your machine, and it's how most people do it today.
So why should this be a problem? Why should you even care?
The computer you work with today is a different computer tomorrow. In the background, your Windows or Unix machine is updating again and again:
This potentially influences the application under test. And that's a problem in software testing.
As it may interfere with the software under test, you need to have it under control with the so-called configuration management. This means you always know with which configuration you tested your software.
If you're not in control of your system, your test can't be reproducible.
Let's assume the software you'd like to test doesn't start on your computer. You ask a developer what dependencies there are, and the developer says you need to install the runtime library XYZ. So you do that. The software to be tested now starts on your PC, and you can test without any findings.
But as the first customer installs the software and doesn't have this library either, he runs into the same problem: the software doesn't start.
You destroyed your configuration by installing the library, as you no longer have the system under configuration control.
Besides that, you have individual configurations on your machine. This may influence your tests as well.
As mentioned above, your tests can't be reproducible if you do not control your system. Your tests have to be reproducible. If they're not, you're left to chance.
And keep in mind that even the test software itself is already an interference that could have an interdependency with the software under test.
There's an easy way to solve this: use a system where you have control over the configurations, like a virtual machine (VM). A VM is an image of the computer, which you can always reset and control the updates. It's not the idea to not update the system. It's about controlling it and updating all systems used for testing simultaneously.
Configuration control means there are no unknown changes in the system.
If you sign up for a free Azure account, you get a VM free of charge for 12 months. Create Your Azure Free Account Today | Microsoft Azure