5 biggest mistakes while tackling coding assessments

Jerzy Zawadzki - Chief Technology Officer
5 minute(s) read

For the past few years, I have checked and graded over a hundred coding assessments. From what I found, I’ve made a short list of the most common and biggest mistakes.

I won’t go too deep into technical errors (like writing duplicated or unmaintainable code). I will focus on more overall things instead. Following thoughts can be applied to every programming language and coding assessment. It doesn’t matter if it’s PHP recruitment task or Python or React. Even one of the these mistakes can cause your candidature's rejection! (P.S. Don’t try it at home)

So let’s go!

1. First: it must do the job. Quality comes second.

Of course, we all get this — you want to show yourself and your skill. You want your code to be perfectly crafted, with extendable architecture. You want to show off knowledge of design patterns. All of this is important, but the crucial thing is to meet the criteria of success of the exercise — to write a correct algorithm. If incorrect, even the most beautiful code won’t get you anywhere. Remember: most of the code assessments are time-limited. Firstly, focus on solving it. You can polish it later.

2. Not running your code before sending it out.

If you got to this point and you were like: “WHAAAT? How could someone not run and test their code before sending it?!”, you are right. Believe me, many times I’ve seen code unable to be parsed, with obvious typos or even ones that simply lacked semicolon. Run your code. Prepare your coding environment with needed infrastructure beforehand, so you don’t waste time during the task. If you don’t know what to expect, ask the recruiter.

3. Commenting your code too much. Or not at all.

Oh, yes, you comment your code. You recycle. We know it. But you know what: commenting EVERY single line of it is a bit too much. And we all know you probably won’t comment that much on your real-life coding. BTW this applies to the whole code, not only comments: I always assume that code written during recruitment will be 100% sure than every-day code. Comment why you do your code this way, not what you are doing.

4. Do not copy other people’s solutions.

This one should be obvious, I hope. Most companies will keep history of the tasks sent to them, and some of them have anti-plagiarism mechanisms built into their recruitment tools. Noticing the plagiarism is way easier than you might think.

5. Not following the instructions.

Last but not least. Writing code is not the only thing you will do during the task. You also need to send your solution. This includes e.g. committing code to repository, or sending it via e-mail.

Sometimes there might be some additional rules regarding (e.g. to remove node_modules or format your solution in a specific way). Do as you are asked to. You may think this is not a part of the recruitment task, but let’s be honest – if you can’t follow the instructions, it may work against you…


If everything goes well and you are invited to the technical interview, think about the solution you sent. There is a big chance that interviewer will ask you about it: what was the biggest trouble for you, what are the other ways this could be solved or what can you improve after time limit hit. Be prepared.

That’s it. Hope you liked it! If you'll get 10/10 on your next recruitment task because of any advice above, let me know!

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