Super Simple Observer Pattern Example

I keep destroying my own blog postings by accident. I wrote a really cool one about four animals being poisioned by a nuclear explosion which served as an example of the observer pattern. It is gone now. I offer the following instead. First take in these three classes:

1. namespace FubarApp.Objects
   {
      public class Foo
      {
         public bool IsAltered { get; set; }
         
         public Foo()
         {
            IsAltered = false;
         }
         
         public void UpdateAlteredState(bool value)
         {
            IsAltered = value;
         }
      }
   }
    
2. namespace FubarApp.Objects
   {
      public class Bar
      {
         public bool IsAltered { get; set; }
         
         public Bar()
         {
            IsAltered = false;
         }
         
         public void UpdateAlteredState(bool value)
         {
            IsAltered = value;
         }
      }
   }
    
3. using System;
   namespace FubarApp.Objects
   {
      public class Fubar
      {
         public Action AlterationStateUpdater;
      }
   }
    

Alright, here they are in action! (pun intended)

using FubarApp.Objects;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace FubarApp.Tests
{
   [TestClass]
   public class UnitTest
   {
      [TestMethod]
      public void Test()
      {
         //start as false
         Foo foo = new Foo();
         Bar bar = new Bar();
         Assert.AreEqual(foo.IsAltered, false);
         Assert.AreEqual(bar.IsAltered, false);
         
         //still false
         Fubar fubar = new Fubar();
         fubar.AlterationStateUpdater = foo.UpdateAlteredState;
         fubar.AlterationStateUpdater += bar.UpdateAlteredState;
         Assert.AreEqual(foo.IsAltered, false);
         Assert.AreEqual(bar.IsAltered, false);
         
         //no longer false
         fubar.AlterationStateUpdater(true);
         Assert.AreEqual(foo.IsAltered, true);
         Assert.AreEqual(bar.IsAltered, true);
      }
   }
}