Is it okay to leave tests in your code? (programming.dev)

submitted 4 months ago* (last edited 4 months ago) by [email protected] to c/[email protected]

19 comments fedilink hide all child comments

Like if I'm using print statements to test my code. Is it okay to leave stuff like that in there when "publishing" the app/program?

Edit: So I meant logging. Not "tests". Using console.log to see if the code is flowing properly. I'll study up on debugging. Also, based on what I managed to grasp from your very helpful comments, it is not okay to do, but the severity of how much of an issue it is depends on the context? Either that or it's completely avoidable in the first place if I just use "automated testing" or "loggers".

you are viewing a single comment's thread
view the rest of the comments

[-] [email protected] 3 points 4 months ago* (last edited 4 months ago)

Great question.

There’s no universal rule against it and descriptive logs and errors are considered good practice, but one-off test statements in output are a common code smell, which isn’t a proper bug but suggests there might be one elsewhere.

Why?

The reasoning for this varies but for example:

in most settings, output is expected to be meaningful; for example a print statement in a C program is included in its result and expected to be parsable, even if it’s just a number like 0 (success)
logging specific values can expose runtime data that sometimes shouldn’t be exposed, or can otherwise offer an attacker intel about the application structure
debug statements in logging can indicate the dev has not yet learned to use a debugger, the preferred tool for that job
logging non-descriptive or otherwise unhelpful messages can indicate the developer is aware of a bug they’re attempting to catch on prod, or maybe just has a habit of not cleaning up after themselves
otherwise, obvious output-based testing might suggest the developer is not writing unit tests or maybe has no test harness at all, which for any larger application is a big red flag to most experienced developers

Again there’s no hard and fast rule against it, and whether it’s frowned upon depends on the context. For example, I actually expect slapdash logging in stuff like one-off scripts, app mockups, recently scaffolded projects, and so forth.

Also, not every codebase merits a full testing solution. I would consider it a form of premature optimization, which is more of a process inefficiency than a mistake but should still be avoided.

Most importantly, it’s OK to be a beginner. I wouldn’t think poorly of a developer due to a code smell like this. It’s more like an opportunity to learn, and IMO you’re ahead of the game for even thinking to ask.

Edit: use spoiler for info dump

this post was submitted on 10 Apr 2025

20 points (100.0% liked)

No Stupid Questions (Developer Edition)

1058 readers

1 users here now

This is a place where you can ask any programming / topic related to the instance questions you want!

For a more general version of this concept check out [email protected]

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

founded 2 years ago

MODERATORS

[email protected]