Update Odin Project content (#856)

content/odin/javascript/testing_javascript/testing_basics.md

@@ -21,6 +21,7 @@ This section contains a general overview of topics that you will learn in this l
 2. Watch at least the first 3 videos of [this video series](https://www.youtube.com/playlist?list=PL0zVEGEvSaeF_zoW9o66wa_UCNE3a7BEr) about testing in JavaScript.  The first video focuses heavily on the WHY, while the next two go into more depth about the process.  Later videos in the series are _definitely_ worthwhile, but the first 3 are enough to get you up and running.
 3. Read and follow the [Getting Started](https://jestjs.io/docs/getting-started) tutorial on the main Jest website. For the upcoming testing practice and project, you only need to follow the instructions for installing jest.
 4. Read and follow the [Using Matchers](https://jestjs.io/docs/using-matchers) document on the main Jest website.  This one demonstrates some of the other useful functions you can use in your tests.
+5. This article explains more about [the why/how and value behind TDD](https://jrsinclair.com/articles/2016/one-weird-trick-that-will-change-the-way-you-code-forever-javascript-tdd/) and also includes some great examples of how to apply it. 
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 ### Knowledge check