MQTTnet/Source/MQTTnet.Tests/Server/Topic_Alias_Tests.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using MQTTnet.Formatter;
using MQTTnet.Internal;

namespace MQTTnet.Tests.Server;

// ReSharper disable InconsistentNaming
[TestClass]
public sealed class Topic_Alias_Tests : BaseTestClass
{
    [TestMethod]
    public async Task Server_Reports_Topic_Alias_Supported()
    {
        using var testEnvironment = CreateTestEnvironment();
        await testEnvironment.StartServer();

        var client = testEnvironment.CreateClient();

        var connectResult = await client.ConnectAsync(new MqttClientOptionsBuilder()
            .WithProtocolVersion(MqttProtocolVersion.V500)
            .WithTcpServer("127.0.0.1", testEnvironment.ServerPort)
            .Build());

        Assert.AreEqual(ushort.MaxValue, connectResult.TopicAliasMaximum);
    }

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

        var receivedTopics = new List<string>();
        var receivedTopicAliases = new List<ushort>();

        var c1 = await testEnvironment.ConnectClient(options => options.WithProtocolVersion(MqttProtocolVersion.V500));
        c1.ApplicationMessageReceivedAsync += e =>
        {
            lock (receivedTopics)
            {
                receivedTopics.Add(e.ApplicationMessage.Topic);
                receivedTopicAliases.Add(e.ApplicationMessage.TopicAlias);
            }

            return CompletedTask.Instance;
        };

        await c1.SubscribeAsync("#");

        var c2 = await testEnvironment.ConnectClient(options => options.WithProtocolVersion(MqttProtocolVersion.V500));

        var message = new MqttApplicationMessage
        {
            Topic = "this_is_the_topic",
            TopicAlias = 22
        };

        await c2.PublishAsync(message);

        message.Topic = null;

        await c2.PublishAsync(message);
        await c2.PublishAsync(message);

        await Task.Delay(500);

        Assert.HasCount(3, receivedTopics);
        CollectionAssert.AllItemsAreNotNull(receivedTopics);
        Assert.IsTrue(receivedTopics.All(t => t.Equals("this_is_the_topic", System.StringComparison.Ordinal)));
        Assert.IsTrue(receivedTopicAliases.All(a => a == 0));
    }
}