WIP: Episode 5 lazy evaluation

drafts/episode5/README.md

@@ -0,0 +1,28 @@
+> This episode is still **Work in progress**
+
+# Building a calculator, episode 3
+
+After finishing [episode 2][episode2] you should have a small codebase
+and test suite, with some functions and an calculator 'object'
+experiment.
+
+To provide some more insight into 'objects', this time we are going to
+do a little experimentation.
+
+Move the provided `calculator.spec.js` into your experiment codebase.
+(that you have set up during [episode 1][episode1])
+
+The file consists of 3 parts.
+
+1. 5 different ways of creating an calculator object
+2. Picking our 'makeCalculator' factory
+3. Testing our calculator
+
+Goal:
+
+1. Try out each form of implementing the calculator
+2. Make sure you understand each form of implementing it
+3. Figure out why certain tests fail in certain cases
+
+[episode1]: https://github.com/matthijsgroen/js-tdd/tree/master/episode1
+[episode2]: https://github.com/matthijsgroen/js-tdd/tree/master/episode2

episode3/README.md

@@ -20,13 +20,17 @@ describe("Regression tests", () => {
 ```
 
 ## Refactoring the add function
-Now we know the code works, we could refactor the `functions` into a
-version with [lamda][lamdas], this is the "Modern way" to define
-functions. They have a slightly different way how the scope works, but
-we get to that later 😅
 
-In short, we will refactor this:
+What is [refactoring][refactoring]?
+The process of refactoring is to structure software by applying a series of refactorings without changing its observable behaviour.
+The last part is important, without changing its observable behaviour. Behaviour can be observed
+with tests and this way we can make sure it does not change while we are structuring our code.
 
+Now we know the code works, we could refactor the `functions` into a version with [lamda][lamdas],
+this is the "Modern way" to define functions. They have a slightly different way how the scope works,
+but we get to that later 😅
+
+For our `add` function we will refactor this:
 ```js
 export function add(left, right) {
   return left + right;
@@ -96,3 +100,4 @@ export const square = (number) => times(number, number)
 [episode2]: https://github.com/matthijsgroen/js-tdd/tree/master/episode2
 [lamda]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
 [4rosd]: https://www.theguild.nl/4-rules-of-simple-design/
+[refactoring]: https://refactoring.com/