A small demonstration of when an object is eligible for Garbage Collection in C#

Demo.cs

using Terminal.Gui;

internal class Program
{
  static View? StaticReferencetoTestObj2;
  public View? InstanceReferenceToTestObj3;
  private static void Main(string[] args)
  {
    // create new instance of program class
    Program This = new Program();
    // start the test and retrieve the list of references
    var refs = This.Test();
    // check wether some new objects can be disposed
    TryCollectAll(refs);
    printCheckAlive(refs);
    // free Instance Reference, collect and print
    Console.WriteLine("Freeing instance reference to TestObj3");
    This.InstanceReferenceToTestObj3 = null;
    TryCollectAll(refs);
    printCheckAlive(refs);
    // free static reference, collect and print
    Console.WriteLine("Freeing static reference to TestObj2");
    StaticReferencetoTestObj2 = null;
    TryCollectAll(refs);
    printCheckAlive(refs);
    //end

  }
  private List<WeakReference> Test()
  {
    List<WeakReference> refs = new List<WeakReference>();
    //create new disposable objects and Weakreferences pointing to them.
    // you can use any disposable class type instead of Terminal.Gui`s View
    View? TestObj1 = new();
    refs.Add(new WeakReference(TestObj1));
    View? TestObj2 = new();
    refs.Add(new WeakReference(TestObj2));
    View? TestObj3 = new();
    refs.Add(new WeakReference(TestObj3));
    View? TestObj4 = new();
    refs.Add(new WeakReference(TestObj4));
    View? TestObj5 = new();
    refs.Add(new WeakReference(TestObj5));
    // retrieve TestObj6 from a function instead of directly from a call to new();
    View? TestObj6 = createTestObj6();
    refs.Add(new WeakReference(TestObj6));
    // create additional references to object 2, 3 and 4
    StaticReferencetoTestObj2 = TestObj2;
    InstanceReferenceToTestObj3 = TestObj3;
    View? LocalReferenceToTestObj4 = TestObj4;

    // check wether the objects are alive
    Console.WriteLine("Initial Check");
    printCheckAlive(refs);
    // dispose objects
    // this is done implicitly to make extending of the test easier
    Console.WriteLine("Disposing all objects");
    foreach(WeakReference wr in refs)
    {
      ((IDisposable)wr.Target).Dispose();
    }

    // Try to collect all objects and check again
    TryCollectAll(refs);
    printCheckAlive(refs);
    // remove references from the TestObjI variables (Except TestObj5) and 
    // make sure all collectible objects are collected.
    Console.WriteLine("Setting TestObjI references to null (except for TestObj5)");
    TestObj1 = null;
    TestObj2 = null;
    TestObj3 = null;
    TestObj4 = null;
    //TestObj5 = null
    TestObj6 = null;
    TryCollectAll(refs);
    // check again
    printCheckAlive(refs);
    // check wether they are actually null
    Console.WriteLine("Are they null though?");
    Console.WriteLine("Is the TestObj1 variable null? " + (TestObj1 is null));
    Console.WriteLine("Is the TestObj2 variable null? " + (TestObj2 is null));
    Console.WriteLine("Is the TestObj3 variable null? " + (TestObj3 is null));
    Console.WriteLine("Is the TestObj4 variable null? " + (TestObj4 is null));
    Console.WriteLine("Is the TestObj5 variable null? " + (TestObj5 is null));
    Console.WriteLine("Is the TestObj6 variable null? " + (TestObj6 is null));
    Console.WriteLine();
    Console.Out.Flush();
    // return so that all leftover locals are freed and the GC evaluates wether their objects are eligible for collection
    Console.WriteLine("Returning from function and freeing locals");
    return refs;

  }
  static void printCheckAlive(List<WeakReference> refs)
  {
    for (int i = 0; i < refs.Count; i++)
    {
      Console.WriteLine("Was test object " + (i + 1) + " Garbage-Collected? " + !(refs[i].IsAlive));
    }
    Console.WriteLine();
  }

  static void TryCollectAll(List<WeakReference> refs)
  {
    foreach (WeakReference r in refs)
    {
      // Code snippet from
      // https://learn.microsoft.com/en-us/dotnet/standard/assembly/unloadability#use-a-custom-collectible-assemblyloadcontext
      // (at the very end of the section)
      for (int i = 0; r.IsAlive && (i < 10); i++)
      {
        GC.Collect();
        GC.WaitForPendingFinalizers();
      }
    }
  }
  static View createTestObj6()
  {
    return new View();
  }
}