Code without tests is bad code. It doesn't matter how well written it is; it doesn't matter how pretty or object-oriented or well-encapsulated it is. With tests, we can change the behavior of our code quickly and verifiably. Without them, we really don't know if our code is getting better or worse.
Four Reasons to Change Software For simplicity's sake, let's look at four primary reasons to change software. 1. Adding a feature 2. Fixing a bug 3. Improving the design 4. Optimizing resource usage