MQTTnet/Source/MQTTnet.Tests/Server/Keep_Alive_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.Packets;
using MQTTnet.Protocol;

namespace MQTTnet.Tests.Server;

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

        var client = await testEnvironment.ConnectLowLevelClient(o => o
            .WithTimeout(TimeSpan.FromSeconds(1))
            .WithTimeout(TimeSpan.Zero)
            .WithProtocolVersion(MqttProtocolVersion.V500));

        await client.SendAsync(new MqttConnectPacket
        {
            CleanSession = true,
            ClientId = "Disconnect_Client_DueTo_KeepAlive",
            KeepAlivePeriod = 1
        }, CancellationToken.None);

        var responsePacket = await client.ReceiveAsync(CancellationToken.None);
        Assert.IsTrue(responsePacket is MqttConnAckPacket);

        for (var i = 0; i < 6; i++)
        {
            await Task.Delay(500);

            await client.SendAsync(MqttPingReqPacket.Instance, CancellationToken.None);
            responsePacket = await client.ReceiveAsync(CancellationToken.None);
            Assert.IsTrue(responsePacket is MqttPingRespPacket);
        }

        // If we reach this point everything works as expected (server did not close the connection
        // due to proper ping messages.
        // Now we will wait 1.1 seconds because the server MUST wait 1.5 seconds in total (See spec).

        await Task.Delay(1100);
        await client.SendAsync(MqttPingReqPacket.Instance, CancellationToken.None);
        responsePacket = await client.ReceiveAsync(CancellationToken.None);
        Assert.IsTrue(responsePacket is MqttPingRespPacket);

        // Now we will wait longer than 1.5 so that the server will close the connection.
        responsePacket = await client.ReceiveAsync(CancellationToken.None);

        var disconnectPacket = responsePacket as MqttDisconnectPacket;

        Assert.IsNotNull(disconnectPacket);
        Assert.AreEqual(MqttDisconnectReasonCode.KeepAliveTimeout, disconnectPacket.ReasonCode);
    }
}