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Let's open up our maintest.js file and
start really using Mocha.

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The first thing to do
is set up a Test suite.

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Remember, a Test suite is a block of
unit tests that are all closely related

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because they test the same function or
they test similar parts of our code base.

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We introduce a test suite
in Mocha using describe.

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Describe is a function
that takes two arguments.

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A string and another function.

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We used a string to describe
what the suite will cover.

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So, for example, let's write a test for

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ourselves to prove that
Mocha is working properly.

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This kind of trivial check
is called a sanity check

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because it's easy to write and

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it verifies that all our code structure
is in proper order before we get started.

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Doing this now will help us confirm that
hings at least worked at some point,

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even if we experience
bugs later down the road.

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Since we're testing our mocha framework,

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I'll just write mocha
as the first argument.

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Mocha is the thing we're testing, so
that's a good title for this suite.

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Now the second argument
is an anonymous function.

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It doesn't require any arguments
it's just a wrapper for

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all of the individual unit tests that
we're going to include within the suite.

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So now with our suite in place we can
start adding some simple unit tests.

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Each individual unit test
is sometimes called a spec.

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And just like our suites,

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Moca makes it natural to write our spec by
containing them in a function called it.

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It is similar to describe.

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The first argument is a string.

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That describes the particular behavior
this unit test is responsible for.

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And again, just as a sanity check for

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myself I'll say should
run our tests using npm.

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The second argument is a function.

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This time the function should
contain all of our expectations for

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this unit, remember an expectation
gives a specific state condition for

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a test to count as passing.

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Otherwise it throws an error.

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So let's import chai at
the top of our file so

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that we can use it as an expectation here.

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So once we have the expect method.

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We can write an expectation
inside of our lonely unit tests.

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So I’ll start by writing
something I know will pass.

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Just to prove that Mocha has
access to this file here.

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Say expects,

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true.to.be.ok.

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So expect true to be okay.

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Now, okay is an assertion method for chai.

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It tests whether some value is truthy,
that means any value besides undefined,

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not a number, false,
an empty string or zero.

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So any value that would satisfy and
if condition.

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Okay, so now if we run npm test and
our console.

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We see some really nice output.

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It says should run our tests using npm.

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Well, that's easy to read and

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informative so
it looks like everything is ready to go.

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In the next video, we'll start writing
our bdd outline for battleship.