DigitalData.MessagingService/tests/DigitalData.MessagingService.Tests/Integration/OutgoingEmailPublisherTests.cs

using System.Text;
using System.Text.Json;
using DigitalData.MessagingService.Publisher;
using DigitalData.MessagingService.Abstraction;
using DigitalData.MessagingService.RabbitMQ;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using RabbitMQ.Client;

namespace DigitalData.MessagingService.Tests.Integration;

/// <summary>
/// Integration tests for <see cref="SendingEmailPublisher"/> against the real RabbitMQ broker.
/// Each test publishes a message and immediately reads it back via BasicGetAsync to verify
/// the full round-trip without starting the consumer (which requires Limilabs Mail.dll).
/// </summary>
public sealed class SendingEmailPublisherTests : IAsyncDisposable
{
    private readonly ServiceProvider _serviceProvider;
    private readonly ISendingEmailPublisher _publisher;
    private readonly RabbitMqConnectionFactory _factory;

    public SendingEmailPublisherTests()
    {
        var services = new ServiceCollection();
        services.AddLogging();
        services.AddMessagingServicePublisher(RabbitMqTestConfig.Apply);

        _serviceProvider = services.BuildServiceProvider();
        _publisher = _serviceProvider.GetRequiredService<ISendingEmailPublisher>();
        _factory = _serviceProvider.GetRequiredService<RabbitMqConnectionFactory>();
    }

    [Fact]
    public async Task EnqueueAsync_PublishesMessage_MessageArrivesInQueue()
    {
        var email = new SendingEmailEvent
        {
            Id = Guid.NewGuid(),
            Recipients = ["test@example.com"],
            Subject = "Integration Test - EnqueueAsync",
            Body = "<p>Hello from integration test.</p>",
            IsHtml = true,
            QueuedAt = DateTime.Now
        };

        var depthBefore = await _publisher.GetQueueDepthAsync();

        await _publisher.EnqueueAsync(email);

        await Task.Delay(300);

        var depthAfter = await _publisher.GetQueueDepthAsync();

        Assert.True(depthAfter >= depthBefore + 1,
            $"Expected queue depth to increase by at least 1. Before: {depthBefore}, After: {depthAfter}.");
    }

    [Fact]
    public async Task EnqueueAsync_MultipleMessages_AllArrivesInQueue()
    {
        var emails = Enumerable.Range(1, 3).Select(i => new SendingEmailEvent
        {
            Id = Guid.NewGuid(),
            Recipients = new List<string> { $"recipient{i}@example.com" },
            Subject = $"Integration Test - Batch #{i}",
            Body = $"Batch message {i}",
            IsHtml = false,
            QueuedAt = DateTime.Now
        }).ToList();

        foreach (var email in emails)
            await _publisher.EnqueueAsync(email);

        await Task.Delay(500);

        // Verify at least one message is present
        var received = await PeekMessageAsync();
        Assert.NotNull(received);
    }

    [Fact]
    public async Task GetQueueDepthAsync_AfterPublish_ReturnsPositiveDepth()
    {
        var email = new SendingEmailEvent
        {
            Id = Guid.NewGuid(),
            Recipients = ["depth-test@example.com"],
            Subject = "Integration Test - GetQueueDepth",
            Body = "Queue depth test",
            IsHtml = false,
            QueuedAt = DateTime.Now
        };

        await _publisher.EnqueueAsync(email);
        await Task.Delay(300);

        var depth = await _publisher.GetQueueDepthAsync();

        Assert.True(depth > 0, $"Expected queue depth > 0, but got {depth}.");
    }

    [Fact]
    public async Task EnqueueAsync_SerializesAllFields_DeserializesCorrectly()
    {
        var id = Guid.NewGuid();

        var email = new SendingEmailEvent
        {
            Id = id,
            Recipients = new List<string> { "serialize@example.com" },
            Subject = "Serialization Test",
            Body = "<strong>Bold</strong>",
            IsHtml = true,
            QueuedAt = DateTime.Now
        };

        await _publisher.EnqueueAsync(email);
        await Task.Delay(300);

        // Read messages until we find the one we just published
        var received = await FindMessageAsync(id);

        Assert.NotNull(received);
        Assert.Equal(id, received.Id);
        Assert.Equal(["serialize@example.com"], received.Recipients);
        Assert.Equal("Serialization Test", received.Subject);
        Assert.Equal("<strong>Bold</strong>", received.Body);
        Assert.True(received.IsHtml);
    }

    /// <summary>
    /// Reads a single message from the queue without acknowledging it (peek via nack+requeue).
    /// </summary>
    private async Task<SendingEmailEvent?> PeekMessageAsync()
    {
        var connection = await _factory.GetDefaultConnectionAsync();
        await using var channel = await connection.CreateChannelAsync();

        var result = await channel.BasicGetAsync(RabbitMqTestConfig.QueueName, autoAck: false);

        if (result is null)
            return null;

        // Nack with requeue=true so the message stays in the queue for consumer
        await channel.BasicNackAsync(result.DeliveryTag, multiple: false, requeue: true);

        var json = Encoding.UTF8.GetString(result.Body.ToArray());
        return JsonSerializer.Deserialize<SendingEmailEvent>(json);
    }

    /// <summary>
    /// Scans queue messages (up to a limit) to find a message matching the given <paramref name="id"/>.
    /// All messages are re-queued after inspection.
    /// </summary>
    private async Task<SendingEmailEvent?> FindMessageAsync(Guid id, int maxMessages = 50)
    {
        var connection = await _factory.GetDefaultConnectionAsync();
        await using var channel = await connection.CreateChannelAsync();

        var requeue = new List<(ulong DeliveryTag, byte[] Body)>();

        SendingEmailEvent? found = null;

        for (int i = 0; i < maxMessages; i++)
        {
            var result = await channel.BasicGetAsync(RabbitMqTestConfig.QueueName, autoAck: false);
            if (result is null)
                break;

            requeue.Add((result.DeliveryTag, result.Body.ToArray()));

            var json = Encoding.UTF8.GetString(result.Body.ToArray());
            var evt = JsonSerializer.Deserialize<SendingEmailEvent>(json);

            if (evt?.Id == id)
            {
                found = evt;
                break;
            }
        }

        // Re-queue all inspected messages so the consumer can still process them
        foreach (var (tag, _) in requeue)
            await channel.BasicNackAsync(tag, multiple: false, requeue: true);

        return found;
    }

    public async ValueTask DisposeAsync()
    {
        await _factory.DisposeAsync();
        await _serviceProvider.DisposeAsync();
    }
}