SWPCore/Tests/Logging/SeqTelemetryChannelTest.cs

using Autofac;
using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.DataContracts;
using SWP.Core.SeqLogging;
using SWP.Core.Telemetry;

namespace SWP.Core.X.TDD.Logging;

[TestClass]
public class SeqTelemetryChannelTest : TestFixture
{
    private CancellationTokenSource _cts;
    private IMessageChannel<ITelemetry> _messageChannel;
    private SeqBackgroundService _service;
    private TelemetryClient _telemetryClient;

    [TestInitialize]
    public void SetupThis()
    {
        //it is important to use the same MessageChannel as the BackgroundService uses
        //we know that IMessageChannel<ITelemetry> _messageChannel; is registered via Autofac and manually injected into SeqBackgroundService
        //so we can get it by calling the Autofac Container in this test.

        _messageChannel = Container.Resolve<IMessageChannel<ITelemetry>>();
        _service = Container.Resolve<SeqBackgroundService>();
        _telemetryClient = Container.Resolve<TelemetryClient>();

        _cts = new CancellationTokenSource();
    }

    [TestMethod]
    public async Task Messages_ShouldBeProcessedFromQueue()
    {
        await _service.StartAsync(_cts.Token);

        for (var i = 0; i < 5; i++)
        {
            var eventTelemetry = new EventTelemetry
            {
                Name = "Test Event 3",
                Timestamp = DateTimeOffset.UtcNow
            };

            eventTelemetry.Properties.Add("TestId", Guid.NewGuid().ToString());
            eventTelemetry.Metrics.Add("TestMetric", 42.0);

            //we don't write to the  _messageChannel.Writer.WriteAsync(eventTelemetry);, but the TelemetryClient which is configured to use SeqTelemetryChannel
            _telemetryClient.TrackEvent(eventTelemetry);
        }

        // wait for processing
        await Task.Delay(5000);

        await _service.StopAsync(CancellationToken.None);

        var hasMoreMessages = await _messageChannel.Reader.WaitToReadAsync();
        Assert.IsFalse(hasMoreMessages, "Queue should be empty after 5 seconds");
    }
}