We have automated tests for some parts of our app, depending on how much value tests add. For example, code that parses data generally has lots of tests. It's

We have automated tests for some parts of our app, depending on how much value tests add. For example, code that parses data generally has lots of tests. It's usually easy to write unit tests for parsers, and it's hard to write parsing code correctly. These tests are invaluable and catch lots of errors, especially when you add features to the parser, or refactor the code, or optimize it. I would not touch any parsing code that doesn't have tests, because no matter how smart you think you are, you are going to break something everytime you make a change. We also have tests for code that interfaces with 3rd party components. When those components change behavior, we can detect problems early. We don't test most UI code, since tests are often difficult to write, need to be updated every time we make changes to the UI, and they catch few bugs.