Author: Erno Pakarinen (erpakari@gmail.com)
Date: 25.11.2019

A simple social network system with Unit tests. It has no real UI, 
main.cpp just executes all test cases and prints results to stdout.

UML class diagram can be found in "doc/design_02.xmi", it's done with
open source UML modeler called Umbrello (available for Linux, Win 
and Mac). A png-format image is also provided in "doc/design_02.png"

The original timetable for this excercise was two hours. It took longer
because I wanted to make comprehensive test cases for the system.
The implementation of the actual SocialNetwork system took less but
test cases made it to take longer than expected.

Class descriptions:

Hobby
    Contains data and operations for a Hobby. Basically this contains only
    one string (name) but I wanted to make it as a separate class instead
    of just having a string data member in Person class.

Person
    Contains data and operations for a Person. Each Person has 
        id
        name
        list of hobbies
        gender
        age
        height
    Hobbies can be added/removed and checked for.

Friendships
    Has all friend relations between two Persons. Holds only id's to Persons. 
    A reason for having friendship relations in a separate class is that now
    there is a single place where all relations are kept. If I would keep 
    friend relations inside the person class I would have to update two Person
    instances when friends are added. With this class the SocialNetwork 
    manages all relations in one place which knows how to handle (add, 
    remove, lookup) friendship relations.

SocialNetwork
    A class which knows all Persons in the system. Has operations to manage 
    and search Persons with specific criteria. All friendships are managed 
    by using the Friendships class owned by the SocialNetwork.

SocialNetworkTester
    Unit test for all classes in the system

PersonNotFoundException
    Exeption which is thrown in certain cases when looking for a specific person.

DebugLogger
    Simple logger for testing purposes

Visual Studio 2019 project/solution is included in SocialNetwork.sln.