function shortWords(array) {
  return array.filter(function(word) {
   return word.length < 5;
  });
}

/* From here down, you are not expected to
   understand.... for now :)


   Nothing to see here!

*/

// tests

function testFunctionWorks(fn, input, expected) {
  const result = fn(input);
  if (
    result &&
    result.length === expected.length &&
    result.every(function(item) {
      return expected.indexOf(item) > -1;
    })
  ) {
    console.log('SUCCESS: `' + fn.name + '` works!');
    return true;
  } else {
    console.error(
      'FAILURE: `' +
        fn.name +
        '([' +
        input +
        '])` should be ' +
        expected +
        ' but was ' +
        fn(input)
    );
    return false;
  }
}

function runTests() {
  const input1 = ['cat', 'oblivion', 'dog', 'patriarchy', 'blue', 'house'];
  const result1 = ['cat', 'dog', 'blue'];
  const input2 = ['rainbow', 'the', 'big', 'broom'];
  const result2 = ['the', 'big'];

  const testResults = [
    testFunctionWorks(shortWords, input1, result1),
    testFunctionWorks(shortWords, input2, result2),
  ];

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

runTests();