It's more fun that way. Instead of your code breaking when you add the test, it's broken until you add the functionality.
My code has many many tests. My co-workers would laugh at me, telling me I spent all my time writing tests. But if my code even RUNS, I'm confident that it is correct. I would get the last laugh, because my co-workers would always be doing frantic debugging right before a deadline because they just uncovered a silent bug.
It's more fun that way. Instead of your code breaking when you add the test, it's broken until you add the functionality.
My code has many many tests. My co-workers would laugh at me, telling me I spent all my time writing tests. But if my code even RUNS, I'm confident that it is correct. I would get the last laugh, because my co-workers would always be doing frantic debugging right before a deadline because they just uncovered a silent bug.