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- We're going to use Jest
as the test framework

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for most of the tests
in this video series.

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So obviously the first thing we need to do

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is to install Jest onto our machines.

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There were two ways to do that.

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You can either use Node
Package Manager, NPM

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or you can use Yarn.

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Let's take a look at both techniques.

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Both are fine.

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Personally I tend to
use Node Package Manager

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but Yarn is equally good.

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So if you want to use Node Package Manager

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to install Jest,

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obviously the first thing

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you have to have Node
Package Manager installed.

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NPM comes with nodejs.

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So if you go to node.js.org

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and download Node.js from there.

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Just click the long term support button.

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It takes a while to download Node.js.

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It installs Python as well,

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plus some C++ libraries.

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So you have to give it a good
five minutes to install it.

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Once you've done that,
you can then use NPM

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to install any libraries
you need, like Jest.

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So let's do that now.

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Just run this command,

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npminstall, the --global flag

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will install Jest globally

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in the NPM folder on your machine.

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So you can run Jest

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from any directory you want to thereafter.

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Okay. So open up a terminal
window or command window.

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Run that command and you now have Jest

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installed on your machine.

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If you prefer to use Yarn then...

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Well, first of all

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if you haven't got Yarn
installed on your machine

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you can actually use NPM to install Yarn

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which seems a little bit roundabout.

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So you can say this,

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open up a terminal
window, or command window,

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npm install --global,
install the Yarn library,

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or the Yarn tool.

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Once you've installed Yarn,

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and that takes a moment or two,

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you can then use Yarn to
install Jest, like this.

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So in the command window

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or in your terminal window,

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yarn global add.

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So in the global Yarn folder,

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we are adding the Jest library.

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Okay. So in both cases

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we should now have Jest
installed on our machine

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ready to use.

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To verify that Jest is installed properly,

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just run this command from a terminal,

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jest --version and all being well,

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it should show a version number.

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So when I'm running this demo myself

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the latest version is 27.5.1.

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Obviously, by the time you
get to watch this video

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it might be a different number.

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Probably will be but that should be fine.

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Let's do that.

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(keyboard clicking)

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Okay. So I have Jest
installed on my machine.

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It was quite straightforward.

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What we're going to
see in the next section

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is how to write some simple tests

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and to run them using the
Jest execution framework.