Implement pub/sub with an IObservable

PubSub4.cs

/*
Output
Name: One Message: Hi
Name: Two Message: Hi
Name: One Message: Hi
Name: Two Message: Hi
Name: One Message: Hi
Name: Two Message: Hi
Name: One Message: Hi
Name: Two Message: Hi
Name: One Message: Hi
Name: Two Message: Hi
*/

using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace UnitTestProject1
{
    class Subscriber
    {
        public string Name;

        //Listen for OnNext and write to the debug window when it happens
        public Subscriber(IObservable<string> observable, string name)
        {
            Name = name;
            var disposable = observable.Subscribe((s) => Debug.WriteLine($"Name: {Name} Message: {s}"));
        }
    }

    internal class BasicObservable<T> : IObservable<T>
    {
        List<IObserver<T>> _observers = new List<IObserver<T>>();

        public BasicObservable(
            Func<T> getData,
            TimeSpan? interval = null,
            CancellationToken cancellationToken = default
            ) =>

            Task.Run(async () =>
            {
                while (!cancellationToken.IsCancellationRequested)
                {
                    try
                    {
                        await Task.Delay(interval ?? new TimeSpan(0, 0, 1));
                        _observers.ForEach(o => o.OnNext(getData()));
                    }
                    catch (Exception ex)
                    {
                        _observers.ForEach(o => o.OnError(ex));
                    }
                }

                _observers.ForEach(o => o.OnCompleted());

            }, cancellationToken);

        public IDisposable Subscribe(IObserver<T> observer)
        {
            _observers.Add(observer);
            return Disposable.Create(observer, (o) => _observers.Remove(o));
        }
    }

    public static class ObservableExtensions
    {
        public static IObservable<T> CreateObservable<T>(
            this Func<T> getData,
            CancellationToken cancellationToken = default)
        => new BasicObservable<T>(getData, default, cancellationToken);

        public static IObservable<T> CreateObservable<T>(
            this Func<T> getData,
            TimeSpan? interval = null,
            CancellationToken cancellationToken = default)
        => new BasicObservable<T>(getData, interval, cancellationToken);
    }

    [TestClass]
    public class UnitTest1
    {
        string GetData() => "Hi";

        [TestMethod]
        public async Task Messaging()
        {
            var cancellationSource = new CancellationTokenSource();
            var cancellationToken = cancellationSource.Token;

            Func<string> getData = GetData;

            var publisher = getData.CreateObservable(cancellationToken);

            new Subscriber(publisher, "One");
            new Subscriber(publisher, "Two");

            for (var i = 0; true; i++)
            {
                if (i >= 5)
                {
                    cancellationSource.Cancel();
                }

                await Task.Delay(1000);
            }
        }
    }

}