Creating multiple tests and expectations

This time, we'll create and test the collection utility module. Create the CollectionUtils.js file in the ~/snapterest/source/utils/ directory:

import TweetUtils from './TweetUtils';

function getNumberOfTweetsInCollection(collection) {
  const listOfCollectionTweetIds = TweetUtils
    .getListOfTweetIds(collection);

  return listOfCollectionTweetIds.length;
}

function isEmptyCollection(collection) {
  return getNumberOfTweetsInCollection(collection) === 0;
}

export default {
  getNumberOfTweetsInCollection,
  isEmptyCollection
};

The CollectionUtils module has two functions: getNumberOfTweetsInCollection() and isEmptyCollection().

First, let's discuss getNumberOfTweetsInCollection():

function getNumberOfTweetsInCollection(collection) {
  const listOfCollectionTweetIds = TweetUtils
    .getListOfTweetIds(collection);

  return listOfCollectionTweetIds.length;
}

As you can see, this function calls the getListOfTweetIds() method from...