#LETSMEETUP

#LETSMEETUP
💬 In this episode, a Senior Frontend Developer at Codete - Magda Kwiecień, will shed some light on using test mocks in one of the most popular JavaScript testing frameworks - Jest. From simple basics to a few lifehacks.
You can explore presented examples on Github:
github.com/kwieccia/jest-mock...
Chapters:
0:00 Intro
0:21 What is mock?
0:42 Why do we need mocks?
2:06 Use cases
2:38 jest.fn()
3:58 jest.spyOn()
5:47 jest.mock()
7:24 Global mocks
8:15 Different function mocks for each test case
9:08 Restore original function for a single test case
9:38 Deal with jest.mock() hoisting
Follow us 👉 / codete
Instagram 👉 / codete_career
Join us 👉 codete.com/career

[@saltwaterkamp]

Absolute straight to the point of the Jest-Mocking API summary of what I need to know right now. Thanks!

[@cachipum]

Great explanation. This is definitely the best video about jest mocking I've found over youtube , thank you so much Magda!

[@CodeteSoftware]

Thank you! We will definitely pass on the kind words to Magda!

[@EdytaKawala]

I felt so overwhelmed - learnig testing and mocks right now. This video is godsent! Thank you

[@magdakwiecien5530]

Pozdrowienia z Lublina! Powodzenia w nauce ☺

[@Serkan0kur]

Great job Magdalena, it is amazing to find everything I need about mocking in one video with examples.

[@artavazdavagyan]

Nice to hear from someone who has experience with testing. over 90% of the videos are usually from people that have just red the manual and have no practice

[@jettlaggg]

I've been reading articles and watching videos about jest mocks and no one explained it as clear and concise as this video. Thank you!

[@CodeteSoftware]

thank you!

[@gmjitendra]

Such a great job done by you Magdalena. You covered all which I was looking for since long. Thank you very much for explaining and sharing code repo.

[@olayinkaola9857]

This is such a packed video. THANK YOU! 1.Functions Mocking using jest.fn(). e.g. Testing a utility 2. Methods mocking using jest.spyOn(). e.g Testing a DataService. Here she tested the dependencies of the DataService. 3. You can mock entire modules using jest.mock(). Jest will automatically provide mock implementations for each methods of this module. You can also selectively override portions of the module by spreading jest.requireActual, and override your target method/function. TOP STUFF Use jest.mock to: 1. simulate JSON config. 2. External Node modules 3. Testing React Components with Enzyme/React Test Library Declare global mocks in your jest.config.js file by listing it under the setupFiles key. Use global mock files to mock GLOBAL STUFF(window object methods and browser APIs). Remember to always set your test environment in jest.config.js You can skip the clever parts for now. But internalise the solution to jest.mock() hoisting problem. The problem is making sure your values are available before use. USE jest.doMock(). They are not hoisted. USE the require statement to import your module. ** Memorize the USE CASES ** ** Watch the video with subtitle on [CC]. **

[@magdakwiecien5530]

And thank YOU for providing the great summary! 😊

[@muhammadporagsarkar7269]

Commenting after watching a lot of videos on this topic and by far this is the most indept yet super easy to understand tutorial... Would have given 100 thumbs up if I could...

[@CodeteSoftware]

[@Liam.Stevens]

Great video! Helped me a lot. Especially the differences between each of the functions

[@vinr]

Super, it covered all the issues I had on jest mocking in 10 mins

[@magdakwiecien5530]

Happy to hear that! 🙌

[@oraclejetster9919]

Magda for president!

[@perrosaurio725]

Thanks, this made it a lot easier to understand.

[@Alexis-ei9ct]

Very clear and concise! Thank you for sharing it.

[@user-tg5ry7yg1w]

This is an excellent video

[@wildcat718]

thanks! this video answered my long lasting questions

[@CodeteSoftware]

We're delighted and encourage you to subscribe so you don't miss out on more valuable videos on our channel !

[@agnieszkakrawczyk6107]

Very interesting content. Magdalena, good job!

[@koderfpv1638]

Great vid! Thanks for table of content! IT will be easier to go back to some topics!

[@stefc4663]

A fantastic video. That last bit about jest.mock hoisting is soo good to know. Those gotchas can take a long time to troubleshoot.

[@CodeteSoftware]

Thank you, we really appreciate it!

[@AGAGARCIA]

Great Video, and Great explain. Good examples. Thanks.

[@oneblackpanda]

thank you very much...

[@jorgesanguinetti1586]

Great video. Is there a place where to find more examples? The official doc is a bit confusing.

[@sprintwithcarlos]

This is a great instructional video, congrats

[@CodeteSoftware]

Thanks Carlos, we appreciate it!

[@fredlove1402]

Thank you! Very helpful!

[@CodeteSoftware]

Thanks!

[@GeorgeBora]

A really good explanation, thank you.

[@Couchwurst]

Perfect! Thank you!! :D

[@user-ci5hf5oe1f]

super clear, thanks!

[@jvinhit]

Great! Thank you for your sharing!

[@haniamania5884]

Super merytorycznie i prezentacyjnie. Jak udalo Ci sie zrobic takie fajny zoomy bez zadnych drgan/ utraty jakosci? 🙂

[@zapfska7390]

I stack overflowed for hours and she covers it all. just missed one thing about mocking modules using __esmodule: true

[@nirash8018]

Thank you Skrillex

[@kobas8361]

Rewelacyjny materiał

[@CodeteSoftware]

Dzięki, zachęcamy do obejrzenia pozostałych filmów

[@ProgrammingWithOsku]

very nice

[@johnswanke6517]

Wow

[@eliasvasques80]

A doubt: "spyOn" with "mockImplementation" really replace the implementation when my file function imports the "spyedOn" function. Or just the instance on the test that i may pass as a parameter?

[@magdakwiecien5530]

It will replace the real implementation - during the time of the test run. Even if this "spiedOn" function is used implicitly, deep inside a file/module/component. (For example, when you test a function from file X that imports a function from file Y that imports a file Z where the "spiedOn" function is declared, it will still be mocked/replaced).

[@eliasvasques80]

@@magdakwiecien5530 I really appreciate that you have responded me. Sorry my english isn't so good.

[@hacking-multiboot904]

exenté explicación

[@adilsaeed31]

Great Video, I learned lots of new things from this video and you are so beautifull :)

[@CodeteSoftware]

Thank you! Stay with us!

[@baboochiku]

Zuberrrrr

[@korkut31]

all codes are wrong. wrong import. you can not resolve paths in JS with out extension. it it not TS.

[@leojohn6702]

Me looking for jest tutorial: hey. wellcome to my advanced jest test. in this tutorial we will tests arrays of numbers. and sum of the elements a + 2 + {username: 'daniel'}; me looking for mooking a mongodb databaase: 😃😃😃😃 : ' yes. this is what I am looking for '

[@CTBell-uy7ri]

Yet another tutorial about mocking that doesn't show how to mock an actual npm package. I guess I'll have to keep looking.....

[@magdakwiecien5530]

Hi, actually it's briefly mentioned at 7:08 - but yes, without detailed explanation, because I don't think there's something particularly complicated about mocking npm package compared to mocking your own, custom ES module. It's the same principle. Quick example, let's say that application uses "uuid" library somewhere: > import { v4 } from 'uuid'; The mock would look just like this: > jest.mock('uuid', () => ({ > v4: jest.fn(() => 'e4ca9391-470d-4d9b-b781-18436fe91c2c'), > }));

[@up.to.mountains]

Акцент писец

[@korkut31]

what kinda accent is that ? uuuu very disturbing. do u from polland ? Serbia ? uffff.