sample node module

app.js

/**
 *
 * Simple, stateless function with no external dependencies.
 *
 * Example:
 *
 *      add(1, 2, 3) === 6
 *
 * To test: verify that add() works for all types of input.
 */
function add() {
    return Array.prototype.slice.call(arguments).reduce(function(acc, el) {
        return acc + el;
    }, 0);
}

/**
 *
 * Simple function that returns an object with default values.
 *
 * @param userId
 * @returns {{userId: *, userName: string, favoriteFoods: Array}}
 *
 * Example:
 *
 *      createNewUserData(4) === {userId: 4, userName: 'New User', favoriteFoods: ['apples', 'oranges']}
 *
 * To test: verify that the value returned matches the expected defaults.
 */
function createNewUserData(userId) {
    return {
        userId: userId,
        userName: 'New User',
        favoriteFoods: ['apples', 'oranges']
    }
}

/**
 *
 * More complex method with an external dependency on http service
 *
 * @param http      an object that asynchronously fetches the resource for user data
 * @param userId    the user id for the data
 * @param success   callback for success
 * @param failure   callback for failure; called if userId is not a positive number or the network call failed
 *
 * Example:
 *
 *      getUserData(http,
 *                  808,
 *                  function(name) { console.log('current user name', name);},
 *                  function(err) { console.log('getUserData failed', err); });
 *
 * To test: verify that success and failure are called at the right times,
 *          and that http is delegated to correctly.
 */
function getUserName(http, userId, success, failure) {
    if (!(typeof userId === 'number' && userId > 0)) {
        failure('invalid user id');
        return;
    }

    http.get('/api/v1/user/' + userId, success, failure);
}

/**
 *
 * Method side effects and no return value
 *
 * @param userDataManager   object responsible for saving user data
 * @param userData          the user data to save. If null, this method will be a no-op.
 *
 * Example:
 *      saveUserData(userDataManager, null) // no-op
 *      saveUserData(userDataManager, data) // data is saved
 *
 * To test: verify that userDataManager.save() is called the right number of times, and under the right circumstances.
 */
function saveUserData(userDataManager, userData) {
    if (userData !== null) {
        userDataManager.save(userData);
    }
}

/**
 *
 * An expensive calculation that can take up to 3000ms
 *
 * @param onComplete    a callback that will be called with the computed value
 *
 * To test: verify that expensiveCalculation eventually calls the callback with a computed value.
 */
function expensiveCalculation(onComplete) {
    setTimeout(function() {
        onComplete('damn this string took a long time to compute')
    }, 2500)
}

/**
 *  Database connection
 */
var connection = {}

/**
 * Get the current count of rows by reading connection
 *
 * @returns {number}
 *
 * To test: verify that rowCount starts at 0.
 */
function rowCount() {
    return connection.rowCount;
}

/**
 * Increment the current count of rows
 *
 * To test: verify that calling this method causes rowCount() to return one more than it previously did.
 */
function addRow() {
    connection.rowCount++;
}

function resetConnection() {
    connection = {
        rowCount: 0
    };
}

resetConnection();

module.exports = {
    add: add,
    getUserData: getUserName,
    createNewUserData: createNewUserData,
    saveUserData: saveUserData,
    expensiveCalculation: expensiveCalculation,
    resetConnection: resetConnection,
    rowCount: rowCount,
    addRow: addRow
}