What would Jesus Developer do?

...using developer approach in digital analytics practice

Presentation for MeasureCamp Czechia 2018 by @cataLuc

Presentation

• What-would-Jesus-Developer-do.pdf

Links and examples

#1 Local development

• Fully-fledged IDEs

  • Eclipse: http://www.eclipse.org/
  • WebStorm: https://www.jetbrains.com/webstorm/
  • IntelliJ Idea: https://www.jetbrains.com/idea/
  • NetBeans: https://netbeans.org/

• Code editors

  • Vim: https://www.vim.org/
  • Emacs: https://www.gnu.org/software/emacs/
  • Sublime: https://www.sublimetext.com/
  • Atom: https://atom.io/
  • At Etnetera Activate we use VSCode: https://code.visualstudio.com/

#2 Version control

• Old-days VCS

  • CVS: http://www.nongnu.org/cvs/
  • SVN: http://subversion.apache.org/
  • Mercurial: https://www.mercurial-scm.org/

• Present-day VCS

  • GIT: https://git-scm.com/
    • Best in combo with GitHub: https://github.com/ (wink wink)

#3 Modular programming (with TDD Demo)

• Install NodeJS: [https://nodejs.org/en/]
• Init NPM package

npm init

• Resulting package.json:

{
  "name": "myPackage",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "ja@lukascech.cz",
  "license": "ISC"
}

• Install Mocha, Chai, supporting modules:

npm install --save-dev mocha chai
npm install fs --save-dev
npm install vm --save-dev

• Update your package.json with test framework configuration:

{
  "name": "myPackage",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "directories": {
    "test": "test"
  },
  "scripts": {
    "test": "mocha"
  }
  "author": "ja@lukascech.cz",
  "license": "ISC",
  "devDependencies": {
    "chai": "^4.1.2",
    "fs": "0.0.1-security",
    "mocha": "^5.2.0",
    "vm": "^0.1.0"
  }
}

• Create getCurrentTimestamp.js file like a hacker:

mkdir src
cd src
touch getCurrentTimestamp.js

• Create another file for your tests:

cd ..
mkdir test
cd test
touch test.js

• Edit test.js and write a test for what getCurrentTimestamp.js should do:

var fs = require("fs");
const vm = require('vm');
var expect = require('chai').expect;

describe('My Test Suite', function () {

  var path = './src/getCurrentTimestamp.js';
  vm.runInThisContext(fs.readFileSync(path, 'utf-8'), path);
  it('getCurrentTimestamp() should return timestamp in ISO format', function () {

    // 1. ARRANGE

    // 2. ACT
    var currentTimestamp = getCurrentTimestamp();
    console.log('returned timestamp: ' + currentTimestamp);

    // 3. ASSERT
    expect(currentTimestamp).to.match(/\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z)/);

  });
});

• Run the test to test that the test fails :wink::

cd ..
npm test

• Write the getCurrentTimestamp.js code:

function getCurrentTimestamp() {
  // Get local time as ISO string with offset at the end
  var now = new Date();
  var tzo = -now.getTimezoneOffset();
  var dif = tzo >= 0 ? '+' : '-';
  var pad = function(num) {
      var norm = Math.abs(Math.floor(num));
      return (norm < 10 ? '0' : '') + norm;
  };
  return now.getFullYear() 
      + '-' + pad(now.getMonth()+1)
      + '-' + pad(now.getDate())
      + 'T' + pad(now.getHours())
      + ':' + pad(now.getMinutes()) 
      + ':' + pad(now.getSeconds())
      + '.' + pad(now.getMilliseconds())
      + dif + pad(tzo / 60) 
      + ':' + pad(tzo % 60);
}

• See that the test passes now:

cd ..
npm test

• Celebrate, refactor happily ever after...

#4 API-based approach

...to be continued