xUnit tests for EventAggregator.cs

EventAggregatorTests.cs

using System;
using System.Collections.Generic;
using Xunit;

// Tests for EventAggregator.cs (https://gist.github.com/mikebridge/f6799ebed20160f72a3daf62f584d2ff)

namespace Messaging.Tests.Unit
{
    public class EventAggregatorTests : IDisposable
    {
        readonly IEventAggregator _hub;
        readonly List<TestEvent> _receivedEvents1;
        readonly List<TestEvent> _receivedEvents2;

        public EventHubTests()
        {
            _hub = new EventAggregator();
            _receivedEvents1 = new List<TestEvent>();
            _receivedEvents2 = new List<TestEvent>();
        }

        public void Dispose()
        {

        }

        [Fact]
        public void It_Should_Publish_An_Event_To_A_Subscriber()
        {
            // Arrange           
            TestEvent receivedEvent = null;
            void Handler(TestEvent e) => receivedEvent = e;

            // Act
            _hub.Subscribe((Action<TestEvent>)Handler); // C# 7
            _hub.Publish(new TestEvent("hello"));

            // Assert
            Assert.NotNull(receivedEvent);

        }

        [Fact]
        public void It_Should_Publish_To_Multiple_Subscribers()
        {
            // Arrange
            _hub.Subscribe((TestEvent e) => _receivedEvents1.Add(e));

            // Act
            _hub.Publish(new TestEvent("hello 1"));
            _hub.Publish(new TestEvent("hello 2"));

            // Assert
            Assert.Equal(2, _receivedEvents1.Count);

        }


        [Fact]
        public void A_Subscriber_Should_Not_Receive_Events_Of_A_Different_Type()
        {
            // Arrange
            _hub.Subscribe((TestEvent e) => _receivedEvents1.Add(e));
            _hub.Subscribe((String e) => { });

            // Act
            _hub.Publish("hello 1");
            _hub.Publish(new TestEvent("hello 2"));

            // Assert
            Assert.Equal(1, _receivedEvents1.Count);

        }

        [Fact]
        public void Multiple_Subscribers_Can_Receive_One_Published_Event()
        {
            // Arrange
            _hub.Subscribe((TestEvent e) => _receivedEvents1.Add(e));
            _hub.Subscribe((TestEvent e) => _receivedEvents2.Add(e));

            // Act
            _hub.Publish(new TestEvent("hello 1"));
            _hub.Publish(new TestEvent("hello 2"));

            // Assert
            Assert.Equal(2, _receivedEvents1.Count);
            Assert.Equal(2, _receivedEvents2.Count);

        }

        [Fact]
        public void A_Subscription_Can_Be_Cancelled()
        {
            // Act
            using (_hub.Subscribe((TestEvent e) => _receivedEvents1.Add(e)))
            {
                _hub.Publish(new TestEvent("hello 1"));
            }
            _hub.Publish(new TestEvent("hello 2"));

            // Assert
            Assert.Equal(1, _receivedEvents1.Count);

        }

        private class TestEvent
        {
            public TestEvent(string message)
            {
                Message = message;
            }

            private String Message { get; }
        }


    }
}