420: Test Database Woes The Bike Shed

Joël shares his recent project challenge with Tailwind CSS, where classes weren't generating as expected due to the dynamic nature of Tailwind's CSS generation and pruning. Stephanie introduces a personal productivity tool, a "thinking cap," to signal her thought process during meetings, which also serves as a physical boundary to separate work from personal life.


The conversation shifts to testing methodologies within Rails applications, leading to an exploration of testing philosophies, including developers' assumptions about database cleanliness and their impact on writing tests.



Avdi’s classic post on how to use database cleaner
RSpec change matcher
Command/Query separation
When not to use factories
Why Factories?


Transcript:


 STEPHANIE: Hello and welcome to another episode of The Bike Shed, a weekly podcast from your friends at thoughtbot about developing great software. I'm Stephanie Minn.


JOËL: And I'm Joël Quenneville. And together, we're here to share a bit of what we've learned along the way.


STEPHANIE: So, Joël, what's new in your world?


JOËL: I'm working on a new project, and this is a project that uses Tailwind CSS for its styling. And I ran into a bit of an annoying problem with it just getting started, where I was making changes and adding classes. And they were not changing the things I thought they would change in the UI. And so, I looked up the class in the documentation, and then I realized, oh, we're on an older version of the Tailwind Rails gem. So, maybe we're using...like, I'm looking at the most recent docs for Tailwind, but it's not relevant for the version I'm using. Turned out that was not the problem.


Then I decided to use the Web Inspector and actually look at the element in my browser to see is it being overwritten somehow by something else? And the class is there in the element, but when I look at the CSS panel, it does not show up there at all or having any effects. And that got me scratching my head. And then, eventually, I figured it out, and it's a bit of a facepalm moment [laughs].


STEPHANIE: Oh, okay.


JOËL: Because Tailwind has to, effectively, generate all of these, and it will sort of generate and prune the things you don't need and all of that. They're not all, like, statically present. And so, if I was using a class that no one else in the app had used yet, it hadn't gotten generated. And so, it's just not there. There's a class on the element, but there's no CSS definition tied to it, so the class does nothing.


What you need to do is there's a rake task or some sort of task that you can run that will generate things. There's also, I believe, a watcher that you can run, some sort of, like, server that will auto-generate these for you in dev mode. I did not have that set up. So, I was not seeing that new class have any effect. Once I ran the task to generate things, sure enough, it worked. And Tailwind works exactly how the docs say they do. But that was a couple of hours of my life that I'm not getting back.


STEPHANIE: Yeah, that's rough. Sorry to hear. I've also definitely gone down that route of like, oh, it's not in the docs. The docs are wrong. Like, do they even know what they're talking about? I'm going to fix this for everyone. And similarly have been humbled by a facepalm solution when I'm like, oh, did I yarn [laughs]? No, I didn't [laughs].


JOËL: Uh-huh. I'm curious, for you, when you have sort of moments where it's like the library is not behaving the way you think it is, is your default to blame yourself, or is it to blame the library?


STEPHANIE: [laughs]. Oh, good question.


JOËL: And the follow-up to that is, are you generally correct?


STEPHANIE: Yeah. Yep, yep, yep. Hmm, I will say I externalize the blame, but I will try to at least do, like, the basic troubleshooting steps of restarting my server [laughter], and then if...that's as far as I'll go. And then, I'll be like, oh, like, something must be wrong, you know,