Add day2 notes

doc/day2.md

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+# Day 2 notes
+
+## Create project directory
+
+* mkdir js-testing
+* cd js-testing
+
+## Create blank npm package file
+
+```shell
+npm init -y
+```
+
+## Install packages we need for testing
+
+```shell
+npm install --save-dev mocha chai
+```
+
+## Install babel for ES6 transpilation
+
+* babel-register - Automatically compile files on the fly by binding to Node require
+* babel-preset-env - Automatically determine babel plugins + polyfills needed
+
+```shell
+npm install --save-dev babel-register babel-preset-env
+```
+
+* Create a babel file for the preset
+
+```shell
+touch .babelrc
+```
+
+* Edit .babelrc
+
+```json
+{
+  "presets": ["env"]
+}
+```
+
+### Create a src file and test file
+
+* In your editor create a directory for source and test
+* Create src function and export it
+
+```javascript
+function day2() {
+}
+
+export default day2;
+```
+
+* Create test script
+* 2 main functions - describe and it
+* Using BDD intergace - also TDD style which uses suite and test
+
+```javascript
+import day2 from '../src/day';
+
+describe('day 2 tests', () => {
+    it('', () => {
+    });
+});
+```
+
+* Run the tests
+
+```shell
+mocha
+```
+
+* We're using ES6 so doesn't work.
+* Need to tell mocha to run using the babel compiler
+
+```shell
+mocha --require babel-register
+```
+
+## First test
+
+* TDD style - write tests first + write code to pass
+* Check that undefined is returned if we pass no parameter
+
+
+```javascript
+    it('should return undefined if no parameter passed', () => {
+        expect(day2()).to.be.undefined;
+    });
+```
+
+* Run tests - don't have chai
+* Import chai expect
+
+```javascript
+import {expect} from 'chai';
+```
+
+* Test now passes because JS returns undefined
+
+## New tests
+
+* Test types
+* Test if it's a string
+
+```javascript
+        it('should return a string when a string is passed', () => {
+            expect(day2('a string')).to.be.a('string');
+        });
+```
+
+* Could just pass back 'some string'
+* Passes 2nd test but first fails
+* Just return 'data'
+
+* Test for number
+* Test for number not being a string
+
+## Check for equals
+
+* Check .to.equal
+* Pass object - check .deep.equal
+
+## Check for contains
+
+* Check for part of a string
+
+## Check for thrown errors
+
+* Pass 'error' as the string we pass
+* Throw an error
+* Wrap function before we test it - will call the function and throw an error
+* Use .to.throw
+
+## Group tests using describes
+
+*
+