Thanks Thisis atest! I appreciate it

Agreed!

Sweet! Glad you enjoyed it, loopduplicate! Thanks for watching.

Leigh Halliday hey Leigh, how to test Mern Stack todo list app please, if you comparing items being fetched and rendered in component should be same number as items stored in DB please ?

Thank you so much :) I'll try to do more on testing!

Thank you! That's awesome :) Tell your friends, tell your parents, tell your boss, tell your kids.

Awesome! Thanks Matthew! :)

Definitely check out "mock service worker" too!

Thanks so much, Anton! I've got a ton of free videos planned this year :)

Thanks Ben, appreciate it!

Yesssss! That's why I make these videos! Please subscribe if you haven't already... my goal is to keep producing a video per week :)

It has now been done :)

Thank you Rubin! I recommend checking out this video next: kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html

@@leighhalliday will do for sure

Thanks so much :) I'm glad the video was able to help!! Being transparent, right now I don't have those videos in my pipeline (because I don't know Vue yet and haven't been using Redux very much lately), but I'll do my best to keep producing videos!!

Thanks ge Dennis!! Stay tuned, more on the way! There's a large backlog of videos and articles on my website to check out too :)

Thank you for the congratulations! Glad you enjoyed it :)

Thank you Léo!! Glad you enjoyed it :)

Glad you're enjoying them, thank you!!

Woohoo!!

Thanks Sam, I recently did a few videos on mocking fetch if you are interested :)

@@leighhalliday I did watch them and have through few of your other videos too. Very good and professional content. Worth a sub. Thanks again.

Sweet!! Thanks :) I'm thinking about my next one now... probably something with GraphQL.

Thank you Mr Ziggy! I recommend you check out this video which is how I prefer to handle Axios mocking these days: kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html

Thank you, Abhishek!

Thank you Vitor!

Hey Ian! Nope you're not missing something... it's sort of magical! But it is actually functionality provided by Jest... it knows to look into the __mocks__ folder to see if that package exists there. Details here: jestjs.io/docs/en/manual-mocks.html

Hey Vivek! This is something that Jest does automatically... __mocks__ is a special folder it looks for and uses when available.

You're very welcome! Check out this video if you would like a good follow-up: kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html

Thanks Nosko! Glad you enjoyed it :)

Thanks Kreator!!

Thank you Wojciech! Glad you enjoyed it! Please subscribe if you haven't yet!

Thank you very much, Igor!

Thank you Mrtech!

Thanks, Ross!!

You're very welcome, Restu!

Thanks, Shiraz!!

Yes! I actually prefer this approach now rather than mocking Axios: kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html

Thanks, Alex!!

Hey Daniel! I'm married to a paisa :) I've been to Medellin many times and have lived there for a short time... I love that city! Thanks for watching!!

That sounds like a great idea. I'll try to plan something :) I actually think in this case you wouldn't do it in the __mocks__ directory, but you'd individually mock your Axios calls for each test to have more fine grained control over what happens.

I think it's automatically built into jest to look inside of that folder.

Hey Alfredo! The one from the _mocks_ dir gets used by default every time, but if I want to test some specific result, like a specific data response or producing an error, I can override it by using mockImplementationOnce() just for a single test.

Hey Iain! Thank you :) I agree, except when it comes to HTTP requests... you can't always talk to a real API when running tests, and if you did, it would make the tests quite a bit slower. I have actually changed my preferred approach though, and it is to intercept the HTTP request rather than mocking fetch... here's a video on it: kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html

@@leighhalliday I get you, thanks for the response I found that video very informative too, subscribed :D

Hey! You can check out what I am using here: uses.tools/leighhalliday

I'm not sure Subhranshu! Maybe someone else watching the video will know :D

Thanks Swapana! Tell us more! Or share a codepen so we can take a look.

Correct. The reason I chose to do it this way is because what the API controls isn't something we control... as an external system we control what we send to it.

Thank you, G!!! :)

Thanks very much Mechraoui!

Well if you're mocking it, the params don't really matter since the request wouldn't be hitting your server. So I think as long as it responds with whatever your code is expecting, you're good to go!

Hey Ping! - It's not that Axios will get angry, but the URL you are fetching every time you run your tests, they may get annoyed you are hitting their API frequently... the biggest problem though is just that your tests will be slow. - It looks like it is using the URL/ENV vars here: github.com/leighhalliday/easy-mobx-redux-comparison/blob/mocking-axios-finished/src/services/unsplash.js but the mocked library is just not performing the actual call.

@@leighhalliday Cool

Thanks for watching, Igor!

Try to think of Cat in the same way as Axios, you can mock it in the same way. Alternatively you could maybe pass the instance of Cat in as a prop to the component... that way it is easier to test because you can pass a fake "Cat" prop when testing. This way you are "injecting the dependency", and can inject fake dependencies for testing.

I believe it is, but to be sure, I recommend reading through the docs here: jestjs.io/docs/en/manual-mocks

en __mocks__/axios.js, usando get: jest.fn() pareciera que lo omite, pero si se reemplaza por get: () => Promise.resolve() ya no lo omite y usa el mock module que definimos. No sé que cambió, que ya no se pueden usar jest.fn( ) en los mock modules que uno define

The pleasure is all mine :)

Shoot, time flies by quickly in JS land eh? In 1 year everything's out of date haha... the concepts I think are mostly the same, but you'll have to see what the latest packages are. I recommend using the video for inspiration, but then looking at the docs themselves.

I think you can mock 404 responses as well.. give it a try!! Check out MSW (mock service worker), I did a video on it if you want to google it.

Hey Taslim! Honestly not sure why!

@@leighhalliday Hey Leigh! Thanks for the reply man. It was my mistake, I fixed it😀

Not sure! Are they better?

as axios return promise, instead using .mockImplementationOnce you can use .mockResolvedValueOnce, although both working fine, but shorter. And as jest has that built in method why not using it

One Monokai

Pretty sure he meant the api provider (unsplash), not axios 👍

I would maybe check out MSW (mock service worker) kzfaq.info/get/bejne/rJ1nmc2csLe4eGQ.html because I've had a bit more luck with it... I prefer it!

I believe I link to it in my article here: www.leighhalliday.com/mocking-axios-in-jest-testing-async-functions

Yup! There are links to the final source code here: www.leighhalliday.com/mocking-axios-in-jest-testing-async-functions

I think I would check out an alternative approach like mock service worker

Thanks :)

If you're a Rails dev, you probably know about the VCR gem which is what I typically use to take a snapshot of the HTTP request... but to be honest you're not really solving anything unless you are constantly invalidating the snapshots and re-creating them... because a 1 year old snapshot only tells you how the API was a year ago. I've heard of the approach of not committing snapshots, and having them expire on maybe a weekly basis... or having a flag you can pass when you run your tests to run them without snapshots but only do this every once in a while. Maybe this is a bad idea, but I'd honestly just say to trust the mock/snapshot until your code tells you otherwise. If you don't have proper error reporting on your production environment to catch and fix errors, you're in trouble anyway. Maybe the focus should be on making your code resilient to APIs that go down, isolating them and allowing the app to run with limited functionality until you can push a fix up. GET requests can use old/cached results, POST/PUT requests can be done in the background such in Sidekiq or whatever the JS equivalent is, and re-run the failed jobs once you push out a fix. Thanks for the suggestions :) I'll do my best!

Dont mock what you dont own

You should not test what you don't own, so you should not test Unsplash API. If they roll out breaking changes in their API, you are screwed just as everybody else. You must be confident that stable API do not bring breaking changes. Anyway if the API breaks, it would be reflected directly in production and your users will face the broken API long before you trigger your tests

Hola Yenifer! Gracias por escribir! I published a very small repo showing how to test both the positive (valid link) and negative (invalid link) scenarios... there are some details in the README about the 3 files you should pay attention to: github.com/leighhalliday/minimal-mocking-axios-demo

@@leighhalliday thank so much i really appreciate it

Cause I didn't know it existed :) But it's good to know how to do it by hand anyway for when you have to.

Sure thing! Feel free to ask me on Twitter (and share the example you're struggling with)... I'll do my best to help out. twitter.com/leighchalliday

@@leighhalliday i already send you a tweet thanks for helping me

Just replied on twitter :)

Ya tu lo sabes chico! Vamos mi verde! ps - I have a channel in Spanish if you're interested in "contenido de alta calidad en español" hehe: kzfaq.info

why?

I agree with you for the most part, Jaime... sometimes I prefer this approach to mocking things like Axios though rather than creating wrapper functions and mocking them instead... I'd rather deal with the potential issues I'd run into by having mocked Axios than having 10-15 tiny functions whose only purpose is to avoid mocking Axios directly.

@leigh I was thinking that wrapping axios will prevent me from changing test when my implementation changes. And I imagine using axios or any http lib is pervasive in codebase that you need to abstract it?

@Aleksandr there are better blog posts that can explain you more about this by google search for “dont mock what you dont own”

Thanks TDDIRLAF! What do you mean?