All language subtitles for 002 What & Why__en

So before we get started writing any code,

what actually is testing?

Well, we did test a lot in this course already,

we did a lot of manual testing.

So that means that we, as a developer, write some code

to implement a certain feature or fix a certain issue

and then of course, we preview that application

in the browser and we test it there.

That's what we do all the time as developers,

that's what we did all the time in this course,

it's super important because we see what our users will see

and we definitely wanna polish that

and make sure that this works,

and that this is not going to go away.

But, testing the app manually is also error-prone,

at least if it's the only kind of testing you do.

Simply because it's hard to test

all possible combinations and scenarios.

If you have a very complex React app

with a lot of different pages and features,

and you then add a new feature,

or you change an aspect of an existing feature,

you will probably test that change

or that new feature,

but you're not going to test all the other parts

of your application all the time.

And therefore, you might change something

which breaks some other feature in your app

and since you're not testing everything all the time,

that breaking change, that bug,

might slip through and maybe you eventually catch it later,

but that's not guaranteed and you might catch it too late

and it might then cause some extra work.

And that's where automated testing steps in.

This is not a replacement for manual testing,

manual testing will always be super important,

but it's an addition.

With automated testing, you write extra code

that runs and tests your other code,

your main application code.

And this might sound super weird,

but this is a standard procedure,

a standard thing to do in modern development.

And the good thing abut that is,

that since you write code

that tests your entire application automatically,

you can always test everything no matter what you changed

because you will automatically then test

your entire application,

it doesn't cost you a lot of time to do that.

And therefore, you typically write such tests,

such automated tests that test

the different individual building blocks of your app,

but where you then test all those building blocks together,

whenever you make changes to your code basically.

Instead of testing only parts of your app from time to time.

And that's therefore very technical,

but it allows you to test everything all the time

and combined with manual testing,

that allows you to catch errors way earlier

and it allows you to write

and ship better code in applications.