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Apr 4, 2022

Testing with Jason Swett

Jason Swett is the author of the Complete Guide to Rails Testing. We covered Jason's experience with testing while building relatively small Ruby on Rails applications. Our conversation applies to just about any language or framework so don't worry if you aren't familiar with Rails. A few topics covered: - Listen to advice but be aware of its context. Something good for a large project may not apply to a small one - Fast feedback loops help us work quicker and tests are great for this - If you don't involve things like the database in any of your tests your application may not work at all despite your tests passing - You may not need to worry about scaling at the start for smaller or internal applications - Try to break features into the smallest pieces possible so they can be checked in and reviewed quickly - Jason doesn't remember the difference between a stub and a mock because he rarely uses them Related Links: - Code with Jason - The Complete Guide to Rails Testing - Code With Jason Podcast Transcript: [00:00:00] Jeremy: today I'm talking to Jason Swett, he's the author of the complete guide to rails testing, a frequent trainer and conference speaker. And he's the host of the code with Jason podcast. So Jason, welcome to software sessions. [00:00:13] Jason: Thanks for having me. [00:00:15] Jeremy: from listening to your podcast, I get a sense that the size of the projects you work on they're, they're relatively modest. Like they're not like a super huge thing. There, there may be something that you can fit all within your head. And I was wondering if you could talk a little bit to that first, so that we kind of get where your perspective is and the types of projects you work on are. [00:00:40] Jason: Yeah. Good question. So that is true. Most of my jobs have been at small companies and I think that's probably typical of the typical developer because most businesses in the world are small businesses. You know, there's, there's a whole bunch of small businesses for every large business. And so most of the code bases I've worked on have been not particularly huge. And most of the teams I've worked on have been relatively small And sometimes so small that it's just me. I'm the only person working on the application. I, don't really know any different. So I can't really compare it to working on a larger application. I have worked at, I worked at AT&T so that was a big place, but I was at, AT&T just working on my own solo project so that wasn't a big code base either. So yeah, that's been what my experience has been like. [00:01:36] Jeremy: Yeah. And I, I think that's interesting that you mentioned most people work in that space as well, because that's basically where I fall as well. So when I listened to your podcast and I hear you talking about like, oh, I have a, I have a rails project where I just have a single server and you know, I have a database and rails, and maybe I have nginx in front, maybe redis it's sort of the scale that I'm familiar with versus when I hear podcasts or articles, you know, I'm reading where they're talking about, oh, we have 500 microservices or we have 200 instances of the application. That's, that's not a space that I've, I've worked in. So I, I found it helpful to, to hear, you know, from you on your show that like, Hey, you know, not everybody is working on these gigantic projects. [00:02:28] Jason: Yeah. Yeah. It's not terribly relatable when you hear about those huge projects. And obviously, sometimes, maybe people earlier in their career can get the wrong idea about what's applicable to their situation. I feel like one of the most dangerous kinds of advice is advice that's good advice, but it's good advice for somebody else. And then I've, I've. Been victim of that, where I get some advice and maybe it's genuinely good advice, but it's not good advice for me where I am doing what I'm doing. And so, I apply the advice, but it's not the right thing. And so it doesn't work out for me. So I'm always careful to like asterisk a lot of the things I say where it's like, Hey, this is, this is good advice if you're in this particular situation, but maybe not for everybody. And really the truth is I, I try not to give advice these days because like advice is dangerous stuff for that very reason. [00:03:28] Jeremy: so, so when you mentioned you try not to give advice and you have this book, the complete guide to rails testing, would you not describe what's in the book as advice? I'm kind of curious what the distinction is there. [00:03:42] Jason: Yeah, Jeremy, right after I said that, I'm like, what am I talking about? I give all kinds of advice. So forget, I said that I totally give advice. But maybe not in certain things like like business advice or anything like that. I do give a lot of advice around testing and various programming things. So, yeah, ignore that part of what I said. [00:04:03] Jeremy: something that I found a little bit unique about rails testing was that a lot of the tests are centered around I guess you could call it like a full integration test, right? Because I noticed when working with rails, if I write a test, a lot of times it's talking to the database, it's talking to if, if I. Have an API or I have a website it's actually talking to the API. So it's actually going through all the layers and spinning up a database and all that. And I wonder if you, you knew how that work, like each time you run a test, is it creating a new database? So that each test is isolated or how does all that stuff actually work? [00:04:51] Jason: Yeah, good question. First. I want to mention something about terminology. So I think one of the most important things for somebody who's new to testing to learn is that in our industry, we don't have a consensus around terminology. So what you call an integration test might be different from what I call an integration test. The thing you just described as an integration test, I might call an acceptance test. Although I happen to also call it an integration test cause I use that terminology too, but I just wanted to give that little asterisk for the listener, because if they're like, wait, I thought an integration test was this. And not that anyway, you asked how does that work? So. It is true that with those types of rails tests, and just to add more terminology into the mix, they call those system tests or system specs, depending on what framework you're using. But those are the tests that actually instantiate a browser and simulating user input, exercise, the UI of the application. And those are the kinds of tests that like show you that everything works together. And mechanically how that works. One layer of it is that each test runs in a database transaction. So when you, you know, in order to run a certain test, maybe you need certain records like a user. And then I don't know if it's a scheduling test, you might need to create an appointment and whatever. All those records that you create specifically for that test that's happening inside of a database transaction. And then at the end of the test, the transaction is aborted. So that none of the data you create during the test actually gets persisted to the database. then regarding the whole database, it's not actually like creating a new database instance at the start of each test and then blowing it away. It's still the same database instance is just the data inside of each test is not being persisted at. [00:07:05] Jeremy: Okay. So when you run. What you would call, I guess you called it an acceptance test, right? Where it's going, it's opening up your website, it's clicking through the website, creating records, things like that. That's happening in a database instance that's created for, I guess, for all your tests that all your tests get to reuse and rails is automatically wrapping your test in a transaction. So even if you're doing five or 10 database queries at the end of all, tha…

1 hr 9 min