What are coding assessment tests?

A coding assessment test is a programming challenge companies send their prospective new hires to see how much they know about writing software. They are generally an online only environment and is timed. Some popular sites are codesignal.com, codility.com.

A bit about me

I’ve been writing software professionally for about 15 years. I’ve held the title of Senior Developer for around 9 years. And I don’t even hate solving puzzles with code. Somewhere in an old repository I have about 50 problems solved from the site projecteuler.net

Why am I terrible at them?

• I think my problem is that it isn’t conducive to how I work. When I run into a novel problem in the real world, I tend to either poke at it or just sit with it then walk away. Then I might come up with something to try and poke at it again. Rinse, Repeat. Eventually I come up with a solution that works. Later I’ll likely go back to it, clean it up and make it better. That approach doesn’t really work when you need to solve the problem within a timed test. I generally do get a solution that works, but it’s never one that I’m proud of.
• They tend to hide the criteria they use to grade your submissions. This feels in bad faith. If I wrote some code at work and was told it was too slow, I would gladly go back and refactor until I got it to a more efficient state. Many times these tests will tell you it works, but not give any information on efficiency. Then after submitting the test it will tell you that your code wasn’t fast enough. Why not tell the test taker that when they have an opportunity to fix it? What real world scenario is like that? There is no logical reason to have performance requirements that are secret.
• It doesn’t test for things that I think are most important. These assessments can easily test for correctness and performance. They cannot test for readability, cleanliness, or maintainability. Those factors are very valuable to a development team, and are harder to find in new hires.

What should companies do instead of online coding tests?

My preference is to offer prospective hires a medium difficulty take home assignment. It could be a puzzle type question, or it could be an example of a real problem they might run into on the job. You could give them 3 or 4 days to complete it. This gives plenty of time to find better solutions through trial and error. I think companies are worried that the candidates may ask someone else to solve something like this for them. Which could happen, but could mostly be rooted out by asking them to explain their solution and why they went with that approach. If they can confidently explain the code in front of you, and go through their thought process, then it’s likely they actually wrote it.

Final Thoughts

Online coding assessments are a gate that can filter out a lot of bad candidates, but it also filters good candidates who may struggle with the testing format. I’ve always seen software development as an iterative process. Write it once, if it fails, try again, re-write it better, clean it up, make it run faster, do it over and over till you can’t find any other way to make it better. An online test that allots 35 minutes doesn’t allow for that.