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");
                }
            }
        }
    }
}