JavaScript Testing with Jest - Crash Course

Learn how to test JavaScript code using the Jest testing framework. Jest is a JavaScript testing framework designed to ensure correctness of any JavaScript codebase. It allows you to write tests with an approachable, familiar and feature-rich API that gives you results quickly.
✏️ Course developed by ‪@CodeWithTomi‬
⭐️ Contents ⭐️
00:00 Intro
00:45 Setting Up Jest
06:22 Basic Concepts In Jest
15:31 Matchers
33:21 Testing Asynchronous Code
49:48 Mock Functions and Spies
1:00:20 Outro
🎉 Thanks to our Champion and Sponsor supporters:
👾 davthecoder
👾 jedi-or-sith
👾 南宮千影
👾 Agustín Kussrow
👾 Nattira Maneerat
👾 Heather Wcislo
👾 Serhiy Kalinets
👾 Justin Hual
👾 Otis Morgan
👾 Oscar Rahnama
--
Learn to code for free and get a developer job: www.freecodecamp.org
Read hundreds of articles on programming: freecodecamp.org/news

[@0xVantwoutMaarten]

Everything is clear,so well done, but for my taste way to easy and basic, could have gone much more in-depth for most devs. Including class mocking, actual mocking use cases, snapshots, setup /teardown, scoping, coverage, many more things I would like to see, but maybe in Part 2!

[@mamadmehdiazizi9401]

so simple tutorial about jest . please release more parts about this topic

[@devworks8787]

much needed one. please add other testing libraries as well especially ones for react

[@M7ilan]

Wow day ago thought it was years ago. Perfect timing for me I guess

[@ankitrawat7211]

Woww!!! This is exactly what I wanted

[@M7ilan]

This man offer very good explanation. Good job!

[@ryanwoods3333]

great! how about more in-depth and with React?

[@salimonwale374]

Great video and lecture. I have been able to link my replit account with my github but I have been unable to link or upload the files of my repositories from replit to github. It's only showing my repositories on github but it's empty. How do I upload the files?

[@juanmacias5922]

46:20
function fetchPromise(isComplete) {
return new Promise((resolve, reject) => {
if (isComplete) {
setTimeout(() => resolve('Hi'), 1000)
}
else {
setTimeout(() => reject(new Error('error')), 1000)
}
})
}
test("fetchPromise is 'Hi'", () => {
return expect(fetchPromise(true)).resolves.toBe("Hi")
})
test("fetchPromise throws", () => {
return expect(fetchPromise(false)).rejects.toThrow("error")
})

[@engineeringmadeasy]

At 7:28. Line 7, dont we need to replace ( "echo \"Error: no test specified\" && exit 1") with ( "jest" ). Instead of "test" with "jest"?? Can someone please clarify. Thanks

[@mitchell4217]

Jump to 13:36. He clarifies here. I think he put this part in here to show that you have to update the value, or the right-hand side of the key: value pair.

[@Franck_Polla]

thank you

[@filippotinnirello]

Got lost around 39:00, why there's a "callback" function inside fetchData? Why the test calls a function (fetchData) of a function (callback)?

[@djdennyjohn]

The callback function is a placeholder for any function that will be passed as an argument when calling fetchData. This pattern is common in asynchronous programming, where you provide a function to be executed once an asynchronous operation (in this case, the timeout) is complete.

[@khalidelgazzar]

Beautiful 😊

[@dylanheslop9161]

I was actually looking for testing react applications... I think the last video you guys uploaded was about a year ago... would like a new updated one

[@haciendadad]

Nice tutorial, but I wish there could have used a more complex example other than that sum function. Still a good video!

[@olakunlemuheeb6229]

Naija to the world 🎉🎉

[@JonathanKila]

Does anyone know why intellisense does not work?

[@ankitasood8589]

Can we not add two import in same file say i want to import sum and myFunction both, on executing this i am getting an error saying module not found ?

[@pratyushkarn1133]

Use named import

[@nested9301]

tf i was about to search jest and this video pops up loool

[@akashojha4127]

First' view on this course ❤❤

[@AmanGUPTA-ht9mj]

Land

[@drekcari]

Is this applicable to typescript?

[@DevBigEazi]

Pls is it?

[@ShoxaKardashian]

What the theme is used in your VSCode?

[@_tot_]

Ya found the answer, mate?

[@ShoxaKardashian]

@@_tot_ no

[@CrazySalieri]

ayu theme

[@rupeshgade4804]

❤❤❤

[@rishiraj2548]

🙏🙂👍

[@moutasim_ayoubi]

JIT video

[@nzubeprecious2914]

Wow Nigeria to the World

[@david-dong]

Thank you LeBron James

[@_tot_]

What theme does he use?

[@juanmacias5922]

2:22 could have just ran "code ." from the terminal to open up VsCode :D

[@Ham.AI.]

ferst

[@AkashRaj-zc6vc]

Not much help because instructor himself is not confident could have been better specially the async part.

[@DukeChameleon]

I like how online courses are starting to cover indian guys giving the lecture by presenting the white guy first

[@dbrandeau]

He does not look nor sound Indian.

[@MdAJIMKhan-qc3cy]

সুবাহানাল্লাহিল আজিম সুবহানাল্লাহি ওয়াবি হামদিহি আস্তাগফিরুল্লাহ

[@helleyequeue]

Can we move away from JS already? It’s getting toxic these days.