If you are a developer you've probably done a test code at least once in your life. A lot of companies request this as a mandatory step in the hiring process. Those tests involve spending 4/5 hours, sometimes even more, writing code that solves a useless problem.
I'm going to explain here why it's rude and it makes you look like an amateur recruiter.
You don't need it
I've been involved in the process of hiring developers both for my own company and while working for others and I never have the need of a technical test.
A 45 minutes conversation with the candidate is more than enough to detect their experience with any technology. It's perfectly fine if you share some code or some actual task from your backlog with the candidate and use it to request opinions, ideas...
Remember you are going to have that conversation anyway because even if the candidate did a very good test you are not going to hire them based on the test only, are you?
So save everybody's time and go to the interview phase directly.
Candidates have lives too
When people are looking for a new job they would, probably, be involved in more than one application process. If each process request them to do a 4/5 hours test code. That could easily mean spending more than 20 hours working on useless stuff. You really want to be part of that nonsense?
There are better alternatives
Let's say that a test code is your thing and nothing is going to change your mind. Ok, so what if next time instead of requesting some useless stuff you ask the candidate to contribute to an open source project related to the skills you are looking for? It could be fixing a bug, developing a feature, reviewing some pull request...
You will have your test and the world will be a better place because an open source project has been improved.
Summary
For companies: Please make the hiring process as smooth as possible. It says a lot about how skilled you are and how you care about developers.
For developers: Go on and contribute to open source projects, solve a bug, help to develop a new feature or just create a pet project in order to have some code ready to be shown if you are requested to.
