In software development is common to test because you need to be sure that a program works correctly.

We either test manually or automatically (yes, we’re nerds afterall), and it’s probably the highest form of caring about your work because you don’t simply do it and do it well, but you double/triple check that everything is fine.

It’s like caring at its highest level at least in work and the testing is a clear sign of how much someone cares about the result of their work.