Instructions

There is a single file called Rover.cs containing a very simple, but untested solution;
You need to refactor it to a more maintainable and testable code;
The program should be written using test driven development, following the red, green, refactor steps;
Please use one or more design patterns when developing your solution. This is your opportunity to show your skills, use it well;
Don't sacrifice tests to complete the solution, this will result in a fail;
We don't mind if the test is incomplete, we are only interested in seeing your approach;
We are looking for the solution to be well factored and to adhere to the SOLID principles.

Github

Fork the project on github.
Commit after every refactor cycle at least.
Don't use branches.
Your solution should be compatible with VS 2015.
If you want to share some thoughts with us feel free to do it on this file.
Try to not spend more than 3 hours to finish the tech test.

Tech Test

A rover has been developed to map out the landscape of Mars. The rover is a robot which can move on a 5x5 grid controlled by simple commands. Write a program which controls the movement of the Mars rover.

The application should be a console app which prompts the controller for the instruction.

Rotate Left : L
Rotate Right: R
Forward: F

The current rover position should be output in the console.

0,0	| 0,1 | 0,2 | 0,3

1,0 | 1,1 | 1,2 | 1,3

2,0 | 2,1 | 2,2 | 2,3

3,0 | 3,1 | 3,2 | 3,3

Requirements

As a controller user I want the rover to be able to rotate left

Given the rover is facing North, when the river rotates Left, Then the rover is facing West.
Given the rover is facing West, when the river rotates Left, Then the rover is facing South.
Given the rover is facing South, when the river rotates Left, Then the rover is facing East.
Given the rover is facing East, when the river rotates Left, Then the rover is facing North.

As a controller user I want the rover to be able to rotate right

Given the rover is facing North, when the rover rotates right, Then the rover is facing East.
Given the rover is facing East, when the rover rotates right, Then the rover is facing South.
Given the rover is facing South, when the rover rotates right, Then the rover is facing West.
Given the rover is facing West, when the rover rotates right, Then the rover is facing North.

As a controller user I want the rover to be able to move forward

Given the Is at position 1.1 and the rover is facing North, when the rover moves forward, the rover is in position 0,1.

As a controller I want to be able to see the rover’s position once it has moved

When the user moves the rover to (1,1), the rover’s position is displayed in the format(1,1)

As a controller I don’t want the rover to be able to move outside the confines of the grid

Given the Rover is facing West and is at position (0,0), when the user tries to move forward, the rovers position does not change

Code

using System;

namespace TechTest
{
    public class Rover
    {
        public enum RoverFacing
        {
            North,
            East,
            South,
            West
        }

        public static void Main()
        {
            var roverPositionX = 0;
            var roverPositionY = 0;
            var roverFacing = RoverFacing.North;

            while (true)
            {
                var command = Console.ReadLine();
                if (command != "L" && command != "R" && command != "F")
                    throw new Exception("invalid command");

                switch (command)
                {
                    case "L":
                        roverFacing = roverFacing == RoverFacing.North ? RoverFacing.West : (RoverFacing)((int)roverFacing - 1);
                        Console.WriteLine($"Rover is now at {roverPositionX}, {roverPositionY} - facing {roverFacing}");
                        break;
                    case "R":
                        roverFacing = roverFacing == RoverFacing.West ? RoverFacing.North : (RoverFacing)((int)roverFacing + 1);
                        Console.WriteLine($"Rover is now at {roverPositionX}, {roverPositionY} - facing {roverFacing}");
                        break;
                    case "F":
                        switch (roverFacing)
                        {
                            case RoverFacing.North:
                                roverPositionX++;
                                break;
                            case RoverFacing.East:
                                roverPositionY++;
                                break;
                            case RoverFacing.South:
                                roverPositionX--;
                                break;
                            case RoverFacing.West:
                                roverPositionY--;
                                break;
                        }
                        Console.WriteLine($"Rover is now at {roverPositionX}, {roverPositionY} - facing {roverFacing}");
                        break;
                    default:
                        throw new Exception("invalid command");
                }
            }
        }
    }
}