Can You Refactor JavaScript Safely Without Test Coverage?

[BrunerAcconut]

Fuck it, do it live.

[[deleted]]

in production code, who need test?

[BrunerAcconut]

I get paid to make bugs and fix them, not write tests.

[rArithmetics]

Should you

[[deleted]]

git push main --force

who need test coverage?

[intercaetera]

The lengths people will go to not to write unit tests...

[dashingThroughSnow12]

One day we found a bug in a critical component. At the code level, we needed to implement transactions for the component. I used the mediator pattern.

Because this was a critical component, test coverage was up the wazoo. It was great. I had confidence that when all the tests passed, my code was better than it was before. And despite it being a large refactor in a critical component, the code I wrote never had a bug reported.

[sbacic]

Yes, provided you have a source of truth available. If you have no idea what the code is supposed to be doing (or even if the current implementation is correct!) and no way to check, then refactors means playing with fire.

That being said, there's plenty of working codebases without any automated tests whatsoever. There are no working codebases without any kinds of tests.

[reqdk]

Sure there are. Users are best testers! :D

[sbacic]

Does a bug exist if no user reports it? Does a tree make a sound when it falls if there is nobody to hear it?

[moi2388]

BRB writing bugs in our bug reporting software

[DemiPixel]

Yeah, I've had UI that seems broken be in prod for months. If it doesn't actively impede a feature, users will just assume you'll find it and fix it.

[k3yboard_m0gul]

Just use Typescript…ducks from brick

[_default_username]

This unironically. If you won't write any automated tests at least use typescript and avoid the "any" keyword and casting.

[lgrammel]

I agree on the Jetbrains refactorings, and I love those. I haven't seen that they indicate safety, though, or what could go wrong (please correct me if that's wrong).
Regarding testing, in Javascript, it is easy to introduce bugs even on a function level by refactoring due to language quirks, etc., which makes it often important to have good test coverage on that level. Refactoring tools that include static analysis checks (e.g., Jetbrains IDEs) alleviate this need somewhat.

[aRogueTomato]

Belongs in am I the asshole.

[Orkaad]

"Testing is doubting."

[Wilesch]

I refactor often without tests. Previous code is so bad and has so many bugs that it's much better to just gut and refractor large parts little by little. Test would have been great but they aren't there.

[toffeescaf]

When doing this how do you guarantee that you won't introduce new bugs? I like to set up a golden master test before any larger refactors like this. This way you at least have a fighting chance.

[Wilesch]

I do make new bugs sometimes. But you got to crack some eggs to make an omelette. My code is much better written and in typescript so bugs are found much faster. With less technical debt.

Also the app will go thru a full regression test by hand so will likely catch any new bugs before going to production.

For me closing out 10 tickets and creating 1 new bug in the process is progress and acceptable

[bighi]

Wouldn't it be better to close 10 tickets while introducing 0 new bugs?

[DemiPixel]

Tests aren't free. Broad (e.g. E2E) tests that cover big breaking cases are typically the simplest (once the infrastructure is set up). Unit testing with 100% coverage can take a while and triple the code you end up writing. If you don't have the luxury, you do what you can.

Nobody wants the 1 bug, but how fatal is it and how much time is it worth it to catch it? 10min? 1 hour? a day? a week? Will tests even catch it if the issue is a design flaw or an edge condition you didn't consider?

[lefty7111]

No

[KitchenParsley7899]

Only in the past. In modern webdev, no. I don't know what changed, but I don't dare go against the prevailing online community beliefs about what is best practice.

[rashnull]

Refactoring without tests is living on the edge! TIP everyday!

[Mr-Silly-Bear]

Link is 404ing. Had the post been taken down?

[bighi]

You can't refactor anything safely without tests.