Java Unit Testing with JUnit - Tutorial - How to Create And Use Unit Tests

[@marmont8005]

Today, I crashed production because I didn't review and test my code. This was a valuable lesson for me. A colleague with more experience showed me how I could have detected this error through unit testing. We wrote 8 test cases within 20 minutes that could have assessed the functionality of my changes, and I would have noticed the bug. I am glad that we have an open culture for acknowledging errors, and that I was 'allowed' to make this mistake.

[@marmont8005]

I didn't realize how I had caused this error until we received emails from the company. In a mapper method, I used .filter(Objects::isNull) in a stream filter instead of .filter(Objects::nonNull). This led to the occurrence of the error on 6000 devices. It dawned on me that a slight oversight can impact hundreds to thousands of people. From now on, I will be more conscientious and refrain from putting my code into production until I am 100% sure that it performs its intended function.

[@JoeyCodes]

How are ya'll getting jobs out here not knowing how to test your code ;-;

[@Roberto-oz6et]

Your channel is pure GOLD! I'm learning more in a few minutes than an whole semester of classes.

[@jeromepincus8529]

So true

[@tejumania]

Honestly there's no better refresher course on java unit testing than this. Short, precise, keeps your gears turning and leaves you wanting to know more. Thank you so much John.

[@micleh]

I enjoyed the topic of the video, since unit tests are not necessarily what you have to do at school (and it's not in the curriculum). What I also liked was you switching to IntelliJ. I've been experimenting with my students, and we tested 3 different IDEs. They said that they felt most comfortable with IntelliJ and also appreciated the helpful tips that guided them towards fixing errors. I'd also like to give you props for the way you present the topics, among them being voice, intonation, gestures and pace.

[@noobster9212]

Truth to be told, curriculum for computer science in most university is outdated. Most lecturers stopped learning new things whereas the cs world is evolving every second.

[@ngndnd]

im taking a junit class rn and its a complete joke of a class.

[@albertbokor6643]

We actually have a course that goes all in on these features. It feels a bit awkward to do this much stuff for a conceptually small assignemt project but still something practically useful.

[@gabrielv.4358]

so true. intellij is the better of them all, and its free

[@impanthering]

@@albertbokor6643 must be nice

[@macmcleod1188]

These are all wonderful. I'm a retired Java 6 programmer writing Minecraft mods in Java 8, 16, and 17. Your videos are clear and concise! They help me a lot.

[@muhammadhassaanbasil8599]

Concise, Crisp & To-the-point. Short videos, really time saving. Great work John.

[@mastershonobi110]

Very noice!!! As a “beginner” learning on my own these lectures are important lessons. Great Intro exposure to thinking about writing code holistically. Ty. 🙌🏿🙏🏾

[@mohamedibrahim-qm1cr]

we should be friends lol i'm also just started Java! maybe CodingMates?

[@mastershonobi110]

@@mohamedibrahim-qm1cr where are you in your journey? Are you taking a course? With who? Asking for potential friend. Lol

[@mohamedibrahim-qm1cr]

@@mastershonobi110 just in java for a week now, I'm in a bootcamp plus resource from Plural Sight.

[@theblindprogrammer]

Yes, John's instructions are clear and to the point.

[@theblindprogrammer]

@@mohamedibrahim-qm1cr Which level are you in? Did you reach objects and inheritance?

[@raghavanaliassaravananm1546]

Thanks and kudos for the Coverage aspect in Intellij IDEA.

[@Hurosaki_]

John, i almost said that this was the most easy topic i learned in java, but when i read other comments, i realized its because your teaching method is simply great. I’m glad i found you!

[@Chronozia]

Hey John! I took a course in the fundamentals of computer science last year where our professor mentioned the importance of unit testing and made us all write our own ones without really explaining the reason why or showing how to properly do it. This video really cleared that up for me. Thank you so much!

[@olillin]

I've been trying to learn unit testing for ages and this made everything so much clearer!

[@beetc305shivsundarbankar9]

Hit the like, if you have been watching many tutorials and finally, you get the proper context with clear explanations.

[@eduonnetcomputer8878]

I have been watching since a year. Your videos are very simple to understand. Thank you.

[@gplus46]

"run our test with coverage" was a requirement for project...Its clearer now. That was a treat. Great video

[@user-zj6iz1rl8d]

i wish this dude made spring boot videoes would be gold

[@samueldnc]

You're brilliant! I'm a senior Java developer but I don't have these didactics and ease to explain/teach. Awesome job

[@ultimateguru2]

Every time i look up something on youtube regarding java, and I see johns video available on that topic, what a sigh of relief, hushhhh.! 😅

[@CodingWithJohn]

Let me know if there's something crucial I haven't covered yet!

[@greatjobbuddy]

I need to give John some major KUDOS. I actually followed the link to his course and now, after like 10% in, I've learned at least 4 or 5 new things that are going to make my life so much easier. Thanks buddy for making these videos and adding a course. Ternary alone is going to save me so much time. A+++

[@CodingWithJohn]

Awesome, thanks! I just added the ternary lesson earlier this week, glad it's helping! I'll be continuing to add new lessons as I'm able, and anyone who has the course already will of course have access to new lessons that are added as well, forever. Also with your permission, if you're ok with it, I might also use your very kind words as a testimonial!

[@greatjobbuddy]

@@CodingWithJohn Absolutely. 100%

[@greatjobbuddy]

Sent you an email.

[@nipunlakshank]

This is the best beginner friendly unit testing tutorial I've found so far

[@lucasalledi]

going through your classes while taking part in a bootcamp. really appreciate your help!

[@CodingWithJohn]

Glad it's helping!

[@kanchankumari2900]

Run our test with coverage, John all the expected points you explained in a very simple way , Thanks for your hard work nd keep on doing such a great real time videos

[@paulus_germanus]

Hands down the best Java channel on YT. I love you John. You just very clearly explained to my dumb brain what the rest of the web really struggled to achieve. Thank you!

[@DevChowdary]

i have not understands this topic in my class but now i am perfect with this topic.... Thank you professor

[@pokitlui]

This video makes the JUnit test case more easily to implement. Thanks. 🎉

[@mrnoname2462]

Been exposed to introduction of JUnit today, lucky to have this lesson!

[@yogeshdharya3857]

Had an assignmen to perform unit testing in Java usign the Junit . Was recommended to watch this video of yours . Your doing a great job ceating content for beginners like me Sir John . Had to subscribe ! Keep up the good and humble work !😇

[@CodingWithJohn]

Awesome, I'm glad it helped! And thankful to whomever recommended it!

[@gabrieldenobrega]

Thank you for this video. It's clear that this video is just a summary of what unit tests are just like you said. However, only your video was able to really make me understand what unit testing in Java is about.

[@DavidKirubi]

No ADs is the silver lining to this channel. 👌

[@milenatenorio2506]

Thank you very much for the video! The teaching and English are perfect for people who do not speak English as a native language.

[@Tolgasah]

Hi John, thanks for the video. I have to write my own unit tests for a project assignment, but have never done or got properly shown how to. This video cleared all my questions.

[@henryicruise860]

I've always been scared of Testing, thanks to this video, I feel quite comfortable with it now.

[@amjadsaad9545]

I'm really thankful to you. I'm currently in the process of studying. And I researched it because my doctor didn't talk about it and I found a similarity between it and the Java language, but it's not a regular Java, it's a test for Java. Thank you. I really understand. And of course I'm proud of myself because I researched who you might laugh at. But that's true. Thank you again❤

[@adrianprayoga335]

underrated java youtuber, man deserve more views, thanks for the tutorial

[@JLSXMK8]

A video on lambdas expressions would be so awesome, especially when the concept is partnered with runnable class instances. These together are the only way I know in java to make a responsive GUI application.

[@my_video_collection]

now 2:23 am, but I'm sitting and watching you. It's so cool. Firstly I'm learning Java, secondly I'm improving my English (at least listening)😍

[@samuvisser]

Long time programmer but never wrote a single unit test. Its this thing i know i should do, but I seriously never have time for. This video is a actually a great example, ur unit tests tend to use as much or even more lines of code than the original. In the real word the next deadline is always yesterday…

[@gabrielv.4358]

That is insanely complicated, wow! So cool!

[@askmax2222]

thanks this clarified a lot that the textbook wouldn't cover

[@whitneythung2792]

This is an awesome tutorial on how to write JUnit Tests. You explained this so well for a slow learner like me. Thanks for the help!

[@CodingWithJohn]

Glad it was helpful!

[@backtashmohammadi2231]

Every video of yours that I watched, I understood very well. You explain very good. 👍🏻 THANK YOU

[@illegalgiant_]

needed a refresher as i apply to sdet jobs. excellent clear stuff. thanks.

[@trexsupreme]

Your videos are GOD SENT! As a person that just started their career as a Java Engineer, I thank you. Keep up the good work.

[@theblindprogrammer]

Keep at it, Java is really nice language.

[@shukria485]

Did you learn byyourself? I'm on that journey

[@theblindprogrammer]

@@shukria485 Yes, I am self taught. Java is not that difficult language to learn if you spend the time to learn it, if you have any questions about Java, let me know, I will help you if I can. Good luck.

[@shukria485]

@@theblindprogrammer that's awesome thank you so much.

[@olemato9460]

I'll pass a string for ut algos to pick up John. He deserves million subs.

[@animeshsrivastavash]

Another great video John! Looking forward to the jvm memory management video; if possible please give it a shot ...

[@DC-sp4sk]

Best video ever on JUnit by a long shot. Would really love to see more advanced videos on this topic!

[@samueloverspelham2322]

As a Java developer, this channel has been very helpful to me in every way.. Thanks to you.

[@tarifadib]

thank you, i was able to create and test individual test cases with this video.

[@waffle8364]

The one testing framework I've ever loved and enjoyed was RSpec for Ruby or Rails. Extremely easy to setup, read and write tests.

[@bandanaboii3136]

This guy knows everything about java 🤯

[@newgentechinfo]

This video really helpful for my next task.Thank you so much John.

[@darsanas6741]

Thanks a lot John. I started loving Java after watching your videos! This topic was so interesting.

[@juancarloscardona5613]

Thanks for this video! I recently joined my first hackathon and I was looking forward to using unit testing in Java for the first time, you explained it very well and it was easy to understand. Nice work :)

[@carloschacon5951]

MinTIC???

[@semilife]

John your videos are great, clear concise and informative.

[@Wow-uj3uj]

This video has made me subscribe. So well spoken and well communicated I had no choice! Thank you for this very informative video

[@slai2389]

Thanks for your video sincerely. Every time I learn new things from you.

[@DavidVCastro]

Amazing how much you covered in 21 minutes!

[@gasynormand8371]

I actually liked the video even i did not started to watch it yet. I wanted this video to come so much. Thank you

[@CodingWithJohn]

Hope it lives up to your expectations!

[@xq510]

THIS IS AMAZING! I loved how you provided context and explained everything so clearly!!

[@oleksiil.9892]

Very cool stuff for a java beginner like myself )) thank you!

[@Roshni1406]

Hey John Thank you so much for this video , you were just explain the basic unit testing in a simple way. This is a great video for beginners.👍

[@sunruiheng4255]

Awesome overview and introduction to JUnit, thanks!

[@khanhsb15]

Thanks John, I understood the basics of JUnit test in Java through your easy to understand examples. 😊

[@kakapyksid]

whenever you have covered a topic, you have become my go-to guy to learn new things. It would be awesome if you covered mocking frameworks as well like Mockito which are probably unavoidable for a developer.

[@tarikuasfaw6405]

Wow I pretty much appreciate you John I am so happy to get your channel

[@simonandris4730]

That was very informative . Thanks for sharing your knowledge with us

[@clublulu399]

Learning Hamcrest is in my opinion another essential library to have a good understanding of. Hamcrest library makes asserting test cases more flexible & intuitive

[@melbali7828]

John you are the best of the best. Keep it up and would like to see some Spring boot tutorials. Many Thanks

[@ndk8111]

Thanks John. Finished your lecture then went to try to implement a few of the junit5 test methods for the very first time. Your explanation was very good. One thing I wished you touched was how to resolve dependencies needed to run junit5. I grabbed one of the dependencies in mvn repository Jupiter-engine and that seemed sufficed to resolve my missing assertTrue(). These small things very briefly but ought to be covered In your demos I think.

[@brenodelgado1128]

Hey John, congrats for your content. It's really clarefull and understood. Thanks from Brazil, let's keep coding.

[@ribamiltombezerradelima3483]

Wow! Thank you so much! Your video is really helpful and engaging! Keep it up,pal!

[@lauraluo7242]

U are amazing bro. For one video, I understand Unit testing.

[@AndrewJesseM]

Thanks for making current and superior Java videos

[@ajithak.s.5224]

Simple and precise illustration. Thank you John. Probably including parametrized junits supported in Junit5 would be better.

[@diegoruiz5265]

You are great John ! I really enjoy your videos, they are so practical but with a lot of useful information and knowledge. You do that complex topic looks really easy and funny. Keep with this awesome work. Thank you !

[@socaljusticewarrior558]

Exactly what I need at my level. I'm at the point where I can make my own software, but my code is all spaghetti and it takes a while to debug. Now I'm going to get into the habit of testing it early and often.

[@mohamed-alimessedi3]

Thank you very much for sharing this in such a clear way.

[@TomAinsworth94]

Awesome vid John, thanks for going into so much detail in an actual use case!

[@saiashok28]

Really good teaching. Thanks for sharing this video.

[@iamhassell]

Great intro to unit testing John, awesome! Thanks!

[@rollingdice]

thanks John, I learned some new info from this lesson

[@dougeighteenfifty980]

Nice intro to unit tests! An intermediate one about Mockito would be an excellent progression.

[@dev_project2012]

very good explanation , I will use more and more unit test

[@nyizeya99]

Your contents are really helping

[@anjananisal2672]

Crystal clear explanation, thank you!!

[@brahmareddydareddy2110]

This is so nice and wonderful way of teaching

[@alexanderanastasiadis9284]

Hi John , you are the reason who i love the Java. Every video is incredible understandable. Thanks a lot 😎

[@lqrock5438]

Hey, first of all, a huge thank you for making these videos! they're great help to me and anyone that is studying and learning java on their own or even in school but need more to understand everything better. Also, I wanted to ask if you have any plans about making a video of how to use an API. I do know it's very simple to look it up in the internet, but your videos are very clear and easy to understand so it would definitely help me a ton! thanks in advance:)

[@theblindprogrammer]

I am just curious, what kind of an API are you looking for? Are you looking for KZbin API or Twitter API? If so, let me know I might attempt it showing you how, I am not as good as John (obviously), but I can try.

[@lqrock5438]

@@theblindprogrammer I was looking for a more general view of it and overall how it works, I have an idea of the process as I studied it in python a year ago in university and even though I can't remember it very well now, if it's anything like python, it should be pretty simple to get into. I practice java by doing small to medium projects and every time I try to implement something new that I've studied into my project, and I'm feeling API's would be a nice addition!

[@theblindprogrammer]

@@lqrock5438 Yeah, calling APIs in Java is similar to python except in Java, it is a lot more verbose than needed. You can try it with news APIs.

[@kemiles]

Appreciate you and this channel ... would love to see you cover mockito!

[@rudralifeandfitness]

Master of coding 🙌 👏

[@pablop46]

Nice work! Really informative video and easy to follow along on

[@thomasLoveJesus]

Thank you John! For such high quality tutorial.

[@umiskan5819]

Great explanation! Great work! Simple and to the point Thank you!

[@adityakeshan8176]

Gold every minute of it

[@dipalisavaliya295]

very nicely explained in short time and covered very good scenarios!! Thanks for your efforts :)

[@oeufleau8543]

About time you started using intellij

[@sirfranciscanadianbacon1468]

That was so well described. Very very helpful. Your videos are also produced very well.

[@Adam-ou1qp]

I attended a 3 hour class which taught me about 75% of what you covered. Your video took 15 minutes...

[@bbaekkhyyunne_4750]

same

[@matiasmoresi5040]

Beautifully explained! Thank you very much!

[@jp77355]

TY!, the exception part was the best in the video!

[@jhonysantosdesouza]

It's a wonderful video!! Many thanks John