shoc-backend/Api.SeaHavenIndustries.Tests/PasswordResetEmailChannelTests.cs

using Api.SeaHavenIndustries.HostedServices;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using Xunit;

namespace Api.SeaHavenIndustries.Tests;

public class PasswordResetEmailChannelTests
{
    [Fact]
    public void A_full_queue_refuses_the_email_instead_of_dropping_it_silently()
    {
        var channel = new PasswordResetEmailChannel(NullLogger<PasswordResetEmailChannel>.Instance);
        for (var i = 0; i < PasswordResetEmailChannel.Capacity; i++)
            channel.TryEnqueue($"user{i}@example.com", "subject", "body").Should().BeTrue();

        var accepted = channel.TryEnqueue("late@example.com", "subject", "body");

        accepted.Should().BeFalse();
        channel.Pending.Should().Be(PasswordResetEmailChannel.Capacity);
    }

    [Fact]
    public async Task A_refused_email_is_never_delivered_and_the_queue_accepts_again_once_drained()
    {
        var channel = new PasswordResetEmailChannel(NullLogger<PasswordResetEmailChannel>.Instance);
        for (var i = 0; i < PasswordResetEmailChannel.Capacity; i++)
            channel.TryEnqueue($"user{i}@example.com", "subject", "body");
        channel.TryEnqueue("late@example.com", "subject", "body").Should().BeFalse();

        var delivered = new List<string>();
        while (channel.Reader.TryRead(out var email))
        {
            delivered.Add(email.EmailTo);
            channel.MarkHandled();
        }

        delivered.Should().HaveCount(PasswordResetEmailChannel.Capacity).And.NotContain("late@example.com");
        channel.Pending.Should().Be(0);
        channel.TryEnqueue("retry@example.com", "subject", "body").Should().BeTrue();
        (await channel.Reader.ReadAsync()).EmailTo.Should().Be("retry@example.com");
    }
}