No testing? What?

Create code without unit tests? No integration tests as well? And no end-to-end tests?
Let's first start with unit tests. What kind of programmer are you when you produce no unit tests? Are you not feeling responsible for your creations?
Mmm, I think I went off the wrong foot here, maybe I shouldn't start off with accusing people. Maybe I should start just with myself, some years earlier.

When I was younger...

Man, did I hate unit tests for 6 years ago! Really, I disliked them a lot and I never created them! Boy was my code rotting back then. Maybe it was because someone figured out creating unit tests was mandatory? When it's obligatory to do something, when you are judged on it, you get an aversion on it. No one needs to tell you what to do, right? It's stupid someone needs to tell you how to develop! And I think you're right about that! Congratulations! You are the best developer ever! 

Turning point?

And at this point you suspect me to I turn this euphorically feeling about the pigheaded developer, who has enough experience to know what's good for coding, around, right? Well, I love to do that. And, most of all I can, but I won't. Not now. Just let me take you back 6 years ago, when I was working at Isala hospital. 

Fixing with great effort

I remember doing a fix at the login screen. The user wanted to let the program remember the role which he/she was logging in. Well, if you know me, I fix with great effort. I really don't like confusing classes and many nested business logic. I didn't read the clean code books or watched any video of it at that time, so I didn't know how to convert a class into clean code. Also I didn't know how to write unit tests. In fact, I did heard the words 'clean code' but didn't know what that meant.

First I was trying some things out and after a few hours I knew how to proceed. I locked myself up, set myself apart from the rest and went on. Maybe you know the feeling I felt at that time: feeling a little sneaky, knowing that you are doing something admirable, but in the mean while guilty because you do not involve anyone on purpose while you should have during a growing numbers of decisions.

And all those decisions where crucial points to be tested. I knew at that time that the number of tests or test cases grew exponentially. And still that didn't kept me from stopping my refactoring and certainly I didn't recommend the testers to watch out for more tests in that specific areas. I went on stripping and re-writing the login page and all the classes involved. (There were also classes who had responsibilities and business logic meant for other functionality, so my refactoring affected a whole lot of functionality other than logging in) 

Throughout the years I've been working at Isala, I was constantly remembered as the guy who dared to re-write that crucial part of the program. 

Good job!

Okay, I felt a little bit like being a hero. And that felt good! Or not quite? What the hell did I do? How did I dare to refactor so much code with so many crucial points in the code any many points of no return. I think it took me a whole week and no one actually knew what I was working on. No one asked me questions about what I was doing either. (During the stand up, I said I was working on it and encountered no problems) 

If I look back at that week, I am smiling now, but boy, what did I take a risk! Especially since I didn't created unit tests at all. Furthermore the code itself had no unit tests as well, so I couldn't be sure enough to determine the quality of my work.

Okay, the result was unbelievably good enough. During manual tests no issues were found. But in production one issue was found and it was corrected real quick (not by me). I was hanging by a thread, as a matter of speaking.

Or not a good job?

So, what is the problem then? I was confident enough to proceed with what I was doing. I thought I was doing good, but I was a Pigheaded stubborn developer: looking for trouble! 

1. I didn't let anyone in during refactoring. So no pair programming, so no extra pair eyes looked at what I was doing.
2. After the rigorously refactoring of a week work, I all checked in at once. So no one could really tell what I did and how I did it because of the many changes, so reviewing was impossible. The whole structure of the previous classes was completely gone.
3. I didn't create any unit tests. Unit tests can help you with weighing your classes and their responsibilities. And most of all, if someone changes the functionality, the unit tests will help you on the existing ones.
4. I didn't create end-to-end tests at first, so the functionality and the user experience wasn't being controlled.
5. I pushed it into production and prayed it worked!

So what did I learn? At that time: nothing!

Conclusion

I don't give you a solution and condemn you. You should figure it out for yourself. You should think about the development you did recently and ask yourself: did I comply to these 5 points?

Note: (There are more advantages with tests, but I only focused on these 5 things, just to point out the danger in writing code.)