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Hey buddy what's going on this is Caleb with Debs Lopes dot com and I'm really really excited to teach

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you about unit testing.

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It's a super super important thing.

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Most developers don't even do but they should definitely know about it and they should definitely do

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it.

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We're going to start by talking about what even is unit testing what's the point.

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And I'm going to start with a little example.

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So I want you to imagine that maybe Apple or Samsung decided to build some brand new phone but as they

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built it they just kept adding in new features or components and apps without ever purposefully planning

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it out or even ensuring that everything worked the way that it was expected to.

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They would just you know throw it in the box ship it off to the consumer.

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And as you can probably imagine you'd probably end up with a really crappy product.

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It's likely though that like with their experience of releasing great products in the past that the

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phone would have some pretty okay parts like maybe the camera would work super well maybe the speakers

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sound nice but what if the experience of everything else was buggy or slow or broke or just plain didn't

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work.

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Apple and Samsung would never ever do this.

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They'd never release a product without extensive testing.

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This is why unit testing is so important for developers.

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But what is it.

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Why should I use it and why don't more developers use it.

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Well unit testing at its most simplest is testing individual components or functionality in a piece

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of software to ensure that it works the way that it's supposed to.

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Simple as that a unit is the smallest testable piece of software.

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It only has one or a few inputs and a single output or result usually.

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Now for example I might write a unit test to ensure the function I wrote works the way that it's supposed

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to my function could handle logging in a user for example.

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Now my test essentially is going to create instances and mock objects of any data models networking

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code etc. that are involved in the log in process at the end of my test.

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I check to see that the expected result actually happens when I run my test it passes meaning that my

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code is good and it's ready for review.

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I can create a pull request.

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It can get approved and then merged into our repository.

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Now we're now getting into the why part of unit testing why bother.

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Well imagine that my company brought on a new junior developer who's unfamiliar with our code base and

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they get tasked with adding some new functionality or even refactoring certain parts of our project.

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Maybe he or she goes into the code that I've written.

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OK and starts messing around unknowingly breaking the log in functionality since they're new to our

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team.

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They forget to run tests and they submit a PR request with their changes.

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It could happen.

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Now since having all tests pass before PR is merged is a requirement at my company the senior devs pulled

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down the project run the tests and see that the log in verification test fails.

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Therefore they can reject the PR and say Hey JR dev fix this and then submit a new poll request.

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That's why testing is super super powerful.

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It saves a lot of stress and headaches from happening before they happen.

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Now it's also helpful to write test for code that you have not even implemented yet.

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This is called test driven development which will talk about a bit in future video but basically you're

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going to write a test which simulates how your code should work when you run it.

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It's going to fail because obviously you haven't actually written any of that implementation code.

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Then you're going to write the code needed to make the test passed.

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You might be really bad code at first but you're going to refactor it.

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At least the test passes right and then at last you do end up refactoring it to make the test pass and

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also make the code clean efficient and only what is simple and necessary.

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Ok that's why it's awesome.

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Not many devs use unit testing as often as they probably should though.

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Ultimately unit testing is a difficult tedious time consuming process which is why a lot of devs choose

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not to use it.

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However it prevents a lot of careless mistakes bad code and also it makes collaborating with others

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on a big project much much easier in the long run.

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So this is a brief overview of unit testing.

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What it is why you should care that should be obvious now and why a lot of devs don't utilize it.

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By the way not a good example you definitely should be using unit tests because it makes things so much

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easier and your code much much cleaner.

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So now we're going to dive into this topic by talking about what makes a good unit tests.

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Let's head over there right now.