MQTTnet/Source/MQTTnet.Tests/Server/Will_Tests.cs

using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using MQTTnet.Client;
using MQTTnet.Internal;
using MQTTnet.Protocol;

namespace MQTTnet.Tests.Server
{
    [TestClass]
    public sealed class Will_Tests : BaseTestClass
    {
        [TestMethod]
        public async Task Intercept_Will_Message()
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
                var server = await testEnvironment.StartServer().ConfigureAwait(false);

                MqttApplicationMessage willMessage = null;
                server.InterceptingPublishAsync += eventArgs =>
                {
                    willMessage = eventArgs.ApplicationMessage;
                    return CompletedTask.Instance;
                };

                await testEnvironment.ConnectClient(new MqttClientOptionsBuilder()).ConfigureAwait(false);
                var clientOptions = new MqttClientOptionsBuilder().WithWillTopic("My/last/will").WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce);
                var takeOverClient = await testEnvironment.ConnectClient(clientOptions).ConfigureAwait(false);
                takeOverClient.Dispose(); // Dispose will not send a DISCONNECT pattern first so the will message must be sent.

                await LongTestDelay().ConfigureAwait(false);

                Assert.IsNotNull(willMessage);
            }
        }

        [TestMethod]
        public async Task Will_Message_Do_Not_Send_On_Clean_Disconnect()
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
                await testEnvironment.StartServer();

                var receiver = await testEnvironment.ConnectClient().ConfigureAwait(false);

                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(receiver);

                await receiver.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("#").Build());

                var clientOptions = new MqttClientOptionsBuilder().WithWillTopic("My/last/will");
                var sender = await testEnvironment.ConnectClient(clientOptions).ConfigureAwait(false);
                await sender.DisconnectAsync().ConfigureAwait(false);

                await LongTestDelay().ConfigureAwait(false);

                Assert.AreEqual(0, receivedMessages.ReceivedEventArgs.Count);
            }
        }

        [TestMethod]
        public async Task Will_Message_Send()
        {
            using (var testEnvironment = CreateTestEnvironment())
            {
                await testEnvironment.StartServer();

                var receiver = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder()).ConfigureAwait(false);
                var receivedMessages = testEnvironment.CreateApplicationMessageHandler(receiver);
                await receiver.SubscribeAsync(new MqttTopicFilterBuilder().WithTopic("#").Build());

                var clientOptions = new MqttClientOptionsBuilder().WithWillTopic("My/last/will").WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce);
                var takeOverClient = await testEnvironment.ConnectClient(clientOptions).ConfigureAwait(false);
                takeOverClient.Dispose(); // Dispose will not send a DISCONNECT pattern first so the will message must be sent.

                await LongTestDelay().ConfigureAwait(false);

                Assert.AreEqual(1, receivedMessages.ReceivedEventArgs.Count);
            }
        }
    }
}