Testing the Observer pattern implementation

To test our implementation, we have to do the following:

1. Open an empty Unity scene but make sure it includes at least one camera and one light.
2. Add a 3D GameObject, such as a cube, to the scene and make it visible to the camera.
3. Attach the BikeController script as a component to the new 3D object.
4. Attach the CameraController script to the main scene camera.
5. Create an empty GameObject, add the following ClientObserver script to it, and then start the scene:

using UnityEngine;

namespace Chapter.Observer
{
    public class ClientObserver : MonoBehaviour
    {
        private BikeController _bikeController;

        void Start()
        {
            _bikeController = 
                (BikeController) 
                FindObjectOfType(typeof(BikeController));
        }

        void OnGUI()
        {
            if (GUILayout.Button("Damage Bike"))
                if (_bikeController) 
                    _bikeController.TakeDamage(15.0f);

           ...