Many important things happen getting to the red bar.
In a test first approach where we write our test before we write our production code, we define the method signature before we build its implementation. That means we are thinking about how to call a method before it is written. This reinforces designing to interfaces and not implementation. These are things I teach in my Software Developer Essentials classes.
Once I have tests in place I can then modify the code and I know that I have the safety net of tests in place supporting me along the way. We also wanted make sure that each test fails for a known reason so that we make sure our tests express a single intention in the system.
Getting to the red bar marks a major step forward in development. It means you have thought about a requirement and how you want to fulfill it, the signature of the method you want to call, what you want it to do and what you want it to return. All of these things are very important in bridging the gap from idea to implementation.
So the next time you get the red bar, celebrate. You’ve earned it!