eggheadio-projects/getting-started-with-redux: null

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
</head>
<body>
  <script src="https://wzrd.in/standalone/expect@22.4.3"></script>
  <script src="script.jsx"></script>
</body>
</html>

/*
 * Open the console to see
 * that all tests have passed.
 */

const addCounter = (list) => {
  return [...list, 0];
};

const removeCounter = (list, index) => {
  return [
    ...list.slice(0, index),
    ...list.slice(index + 1)
  ];
};

const incrementCounter = (list, index) => {
  return [
    ...list.slice(0, index),
    list[index] + 1,
    ...list.slice(index + 1)
  ];
};

const testAddCounter = () => {
  const listBefore = [];
  const listAfter = [0];
  
  deepFreeze(listBefore);
  
  expect(
    addCounter(listBefore)
  ).toEqual(listAfter);
};

const testRemoveCounter = () => {
  const listBefore = [0, 10, 20];
  const listAfter = [0, 20];
  
  deepFreeze(listBefore);
  
  expect(
    removeCounter(listBefore, 1)
  ).toEqual(listAfter);
};

const testIncrementCounter = () => {
  const listBefore = [0, 10, 20];
  const listAfter = [0, 11, 20];
  
  deepFreeze(listBefore);
  
  expect(
    incrementCounter(listBefore, 1)
  ).toEqual(listAfter);
};

testAddCounter();
testRemoveCounter();
testIncrementCounter();

console.log('All tests passed.') || displayInPreview('All tests passed.');




// display in plunker preview
function displayInPreview(string) {
  var newDiv = document.createElement("div"); 
  var newContent = document.createTextNode(string); 
  newDiv.appendChild(newContent);
  document.body.appendChild(newDiv)
}

// Function exported from deep-freeze lib
function deepFreeze (o) {
  if (o===Object(o)) {
    Object.isFrozen(o) || Object.freeze(o)
    Object.getOwnPropertyNames(o).forEach(function (prop) {
      prop==='constructor'||deepFreeze(o[prop])
    })
  }
  return o
}