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This video we're going to take a look at how to get just to essentially fake out this import statement

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or redirect it.

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Here's the entire process.

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This is what we're gonna do in this video.

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The first we're going to do is find the file that we want to make in our case the file that we want

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to fake is our nets wrapper dot t s file inside of our roots s our C directory.

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So this and that's wrapped right here.

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This has all the code that is going to try to actually connect to our real NAT server and we did not

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want to run this code because we don't want to have to run a copy of nets when we are executing our

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tests.

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So this is some code that we want to somehow fake out so to do so we're going to find that file.

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Well just found it then inside the same directory we're gonna create a folder called underscore underscore

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box underscore underscore.

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Let's do that right now.

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Go inside the same directory which in this case to be s RC I'll make a new folder called underscore

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underscore make sure you get two in their box underscore underscore

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after that we're going to open up that folder we've just created and we're gonna create a file inside

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there with identical names the file that we are trying to fake.

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So in our case we are trying to fake or kind of duplicate or redirect Nat's wrapper.

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Yes.

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So you'll make an identically named file inside of underscore underscore Max.

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So that's wrapper dot.

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Yes then inside this file we're going to write out some fake implementation so in our case this is where

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we're going to want to somehow fake out or provide some code to run instead of this Nats wrapper stuff

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so to do so inside of the new file we just created we can do an export onsite Nat's wrapper and I'm

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going to directly return an object.

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So why do I need to do a export continental wrapper.

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Well we are essentially trying to fake out or duplicate the functionality of the real Nats wrapper file.

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The real Nats wrapper file if we go down to the bottom it exports a single named export of Nats wrapper

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and that is going to be an instance of a class or essentially an object.

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So we can't build up or export Nats wrapper and then this is the object that we are going to export

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so we can write out our fake implementation or essentially some code to run instead of the real stuff

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inside of this object.

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Right now I'm going to leave this empty we'll come back and write in some fake implementation in just

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a moment.

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All right.

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Now the last step we're going to make sure that we tell just to use that fake file we just put together

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inside of our test file.

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Right now we have a couple of different files that are essentially trying to make use of this Nats wrapper

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stuff.

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They're specifically the new and update set of tests so inside of my test directory we're going to first

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focus on getting the new test.

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Yes file working correctly so inside of their I'm going to add in an import statement at the top of

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this new test file that's gonna tell just to make use of our mock file but to do so we'll write out

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just not Mark and then we'll write out a relative path to that file that we want to fake.

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So in this case the file we want to fake is Nat's wrapper inside the SRT RC directory that you write

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out a relative path to it.

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We would go up one directory from underscore underscored test into routes up another directory into

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us our C and then we can get Nat's dash wrapper.

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So in total up one directory of one directory that's dash wrapper that whenever these tests are executed

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Justin's going to see that we are trying to mock that file.

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So if anything tries to import that file rather than actually importing the real file just is going

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to redirect that import and give whatever file is trying to import Nat's wrapper.

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Our implementation we wrote out inside of underscore underscore mocks I'm not going to save this this

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you know our tests are not going to run correctly just yet because we do not have any fake implementation

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inside of Nat's wrapper but we should at least see some kind of different error messages inside of our

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tests that at least tell us that this file is being required in or imported instead of the real Nats

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wrapper.

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Let's try this out.

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I'm gonna flip back over.

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I'm gonna restart my test suite entirely

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and we're probably going to still see a lot of errors.

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So I'm going to try to import only urged me run tests only for the new test file that you only run the

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test inside of that new file.

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I'm going to type into this terminal window the letter P which is going to allow us to only run tests

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with a very specific file name of press P.

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I then get prompted on which file I want to try to run.

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I'm going to put in new that's gonna try to find the new test t s file though I'll now see that it's

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only executing at that one test file alone and now we're going to get a very different error message

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compared to what we got before.

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Previously it said oh you have to initialize the client or connect with it before you make use of it.

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Now we're seeing a very different error message one that says cannot read property published of undefined

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which makes me think at least tentatively that this fake implementation is being used instead of our

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real one.

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OK so that's how we kind of set up this import redirecting stuff.

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So now that this is working we're going to take a quick pause.

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Come back next video and figure out how we can somehow write out a useful fake implementation.