Accessing 1st and 3rd items

function accessFirstItem(array) {
    const myArray = array
    return myArray[0]
  }
  
  function accessThirdItem(array) {
    const myArray = array
    return myArray[2]
  }


/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

// tests

function testFunctionWorks(fn, input, expected) {
  if (fn(input) === expected) {
    console.log(`SUCCESS: "${fn.name}" works on [${input}]`);
    return true;
  } else {
    console.log(
      `FAILURE: ${fn.name}([${input}]) should be ${expected} but was ${fn(
        input
      )}`
    );
    return false;
  }
}

function runTests() {
  var list = [1, 4, 9, 16, 25];
  var item1 = 1;
  var item2 = 9;

  var testResults = [
    testFunctionWorks(accessFirstItem, list, item1),
    testFunctionWorks(accessThirdItem, list, item2),
  ];

  var numPassing = testResults.filter(function(result) {
    return result;
  }).length;
  console.log(numPassing + ' out of ' + testResults.length + ' tests passing.');
}

runTests();

Add Item to List

function addToList(list, item) {
    const myArray = list
    myArray.push(item)
    return myArray
  }

/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

// tests

function testAddToList() {
  const input1 = ['red', 'blue', 'green'];
  const input2 = 'pink';
  const expected = ['red', 'blue', 'green', 'pink'];
  const result = addToList(input1, input2);

  if (
    result &&
    result.length &&
    expected.length === result.length &&
    expected.every(function(item) {
      return result.indexOf(item) > -1;
    })
  ) {
    console.log('SUCCESS: `addToList` works!');
  } else {
    console.error('FAILURE: `addToList` is not working');
  }
}

testAddToList();

Make List

function makeList(item1, item2, item3) {
    const myArray = [item1, item2, item3]
    return myArray
}

/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

// tests

function testMakeList() {
  const items = ['prime rib', 'fried goat cheese salad', 'fish tacos'];
  const result = makeList(items[0], items[1], items[2]);

  if (
    result &&
    result.length &&
    items.length === result.length &&
    items.every(function(item) {
      return result.indexOf(item) > -1;
    })
  ) {
    console.log('SUCCESS: `makeList` works!');
  } else {
    console.error('FAILURE: `makeList` is not working');
  }
}

testMakeList();

Return length and Last Element

function findLength(array) {
  const myArray = array
  return myArray.length
}

function accessLastItem(array) {
    const myArray = array
    return myArray.pop()
}

/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

// tests

function testFunctionWorks(fn, input, expected) {
  if (fn(input) === expected) {
    console.log('SUCCESS: `' + fn.name + '` works on `[' + input + ']`');
    return true;
  } else {
    console.error(
      'FAILURE: `' +
        fn.name +
        '([' +
        input +
        '])` should be ' +
        expected +
        ' but was ' +
        fn(input)
    );
    return false;
  }
}

function runTests() {
  const list = [1, 4, 9, 16, 25];
  const originalList = [1, 4, 9, 16, 25];
  const length = 5;
  const lastItem = 25;

  const testResults = [
    testFunctionWorks(findLength, list, length),
    testFunctionWorks(accessLastItem, list, lastItem),
  ];

  const numPassing = testResults.filter(function(result) {
    return result;
  }).length;
  console.log(numPassing + ' out of ' + testResults.length + ' tests passing.');
}

runTests();