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That's FineNot OK

What would Jesus Developer do?

...using developer approach in digital analytics practice

Presentation for MeasureCamp Czechia 2018 by @cataLuc

Presentation

#1 Local development

#2 Version control

#3 Modular programming (with TDD Demo)

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