PlanTempusApp/Tests/MessageChannelIntegrationTests.cs

using Autofac;
using System.Data;
using Insight.Database;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Microsoft.Extensions.Logging;
using Core.Telemetry;
using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.DataContracts;

namespace Tests
{
    [TestClass]
    public class MessageChannelIntegrationTests : TestFixture
    {
        private IMessageChannel<ITelemetry> _messageChannel;
        private SeqBackgroundService _service;
        private CancellationTokenSource _cts;

        [TestInitialize]
        public void SetupThis()
        {
            _messageChannel = new MessageChannel();
            var telemetryClient = Container.Resolve<TelemetryClient>();
            var httpClient = new HttpClient(new TestMessageHandler());
            _service = new SeqBackgroundService(telemetryClient, _messageChannel, httpClient);
            _cts = new CancellationTokenSource();
		}

        [TestMethod]
        public async Task Messages_ShouldBeProcessedFromQueue()
        {
            var processedMessages = new List<HttpRequestMessage>();

            var serviceTask = _service.StartAsync(_cts.Token);

            for (int i = 0; i < 5; i++)
            {
                var eventTelemetry = new EventTelemetry("SomeEvent");
                await _messageChannel.Writer.WriteAsync(eventTelemetry);
            }

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

            _cts.Cancel();
            await _service.StopAsync(CancellationToken.None);


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

        private class TestMessageHandler : HttpMessageHandler
        {
            protected override Task<HttpResponseMessage> SendAsync(
                HttpRequestMessage request,
                CancellationToken cancellationToken)
            {
                return Task.FromResult(new HttpResponseMessage(System.Net.HttpStatusCode.OK));
            }
        }

        [TestCleanup]
        public void Cleanup()
        {
            _cts?.Dispose();
        }
    }
}