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TDD is an acronym
for Test Driven Development.

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As the name implies,

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this concept revolves around the idea
that your software development's flow,

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will be guided by tests.

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It started getting a lot of traction
in the early 2000

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when Kent Beck published a book

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entitled Test Driven
Development by Example.

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You might recognize Kent Beck,

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he is also known for his contributions
to Extreme Programming

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and the Agile Manifesto.

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The fundamental process
of Test Driven Development

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is to write our code by looping
over three main application stages,

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red, green, and refactor.

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For the red stage,

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we start by writing a test
that describes a requirement

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we want our application to fulfill.

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While writing the test,

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we pretend that all the functionality
is already there.

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This test will most likely fail.

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We will then focus on doing
the least amount of work

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necessary to get this new test to pass.

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While at the same time keeping
all the other tests

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we already have in place, still passing.

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As soon as all the tests are passing,

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we have officially reached
the green stage.

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Don't worry if your most recent work
looks a bit messy and hard to read.

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Now we're ready to make our code better.

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It's critical that we perform
incremental improvements and commit often.

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Each improvement can only be accepted
if we keep all tests still passing.

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The refactor phase
can last as long as we want.

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We will stop once we think
our code is looking good enough.

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As soon as we're happy
with the state of the code,

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we can write another test for another
goal we want our application to fulfill.

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This will bring us
right back to the red stage.

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This is the red-green refactor loop

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that is the driving force
behind test-driven development.

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Why don't we put
these concepts to the test?

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In this course,
we will be creating a clone

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of the popular game Wordle,
using test-driven development.

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As we are creating this application,

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we will focus
on how test-driven development

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not only allows you to write software
with robust and clear requirements,

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but also helps you and your team
write very clean and maintainable code.

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Besides learning test-driven development,

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this course will also make use
of Vue 3 and its composition API.

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We will run our tests with Vitest

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and make ample use of Vue test Utils
to help us perform assertions.

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Last but not least, this course
is also a good opportunity

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for us to explore
a little bit of TypeScript.

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I would recommend some basic experience
with Vue before watching this course.

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Don't worry if you've never written
any TypeScript before,

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you'll still be able to follow along
with the content.

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Also, we won't be focusing
on fundamentals and syntax

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of testing tools in this course,

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but rather on the process
of test-driven development itself.

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Therefore,
if you are brand new to testing,

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it might be worth browsing
the Vue Test Utils docs

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or checking out our course
on how to test Vue components first.

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I've left links for both of these
resources in the description below.