ersatztv/ErsatzTV.Core.Tests/Scheduling/RandomizedContentTests.cs

using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Scheduling;
using FluentAssertions;
using NUnit.Framework;

namespace ErsatzTV.Core.Tests.Scheduling;

[TestFixture]
public class RandomizedContentTests
{
    [SetUp]
    public void SetUp() => _cancellationToken = new CancellationTokenSource(TimeSpan.FromSeconds(10)).Token;

    private const int KnownSeed = 22295;

    private readonly List<int> _expected = new()
    {
        5, 7, 7, 8, 6, 7, 8, 9, 10, 7, 5, 1, 7, 2, 5, 6, 1, 4, 5, 6, 4, 5, 1, 6, 5, 7, 1, 3, 9, 9, 9, 3,
        3, 2, 3, 4, 5, 6, 9, 3, 6, 9, 7, 1, 2, 10, 3, 8, 3, 8, 8, 3, 1, 5, 4, 3, 6, 4, 6, 2, 9, 8, 3, 1, 8, 5,
        1, 8, 2, 1, 1, 5, 5, 5, 3, 5, 8, 10, 4, 8, 7, 3, 3, 4, 4, 9, 2, 8, 8, 10, 8, 4, 3, 10, 7, 8, 9, 9
    };

    private CancellationToken _cancellationToken;

    [Test]
    public void Episodes_Should_Randomize()
    {
        List<MediaItem> contents = Episodes(10);

        var state = new CollectionEnumeratorState();

        var randomizedContent = new RandomizedMediaCollectionEnumerator(contents, state);

        var list = new List<int>();
        for (var i = 1; i <= 10; i++)
        {
            randomizedContent.Current.IsSome.Should().BeTrue();
            randomizedContent.Current.Do(c => list.Add(c.Id));

            randomizedContent.MoveNext();
        }

        list.Should().NotEqual(new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 });
        list.Should().NotEqual(new[] { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 });
    }

    [Test]
    public void State_Index_Should_Increment()
    {
        List<MediaItem> contents = Episodes(10);
        var state = new CollectionEnumeratorState();

        var randomizedContent = new RandomizedMediaCollectionEnumerator(contents, state);

        for (var i = 1; i <= 10; i++)
        {
            randomizedContent.State.Index.Should().Be(i);

            randomizedContent.MoveNext();
        }
    }

    [Test]
    public void State_Should_Impact_Iterator_Start()
    {
        List<MediaItem> contents = Episodes(10);
        var state = new CollectionEnumeratorState { Index = 5, Seed = KnownSeed };

        var randomizedContent = new RandomizedMediaCollectionEnumerator(contents, state);

        for (var i = 6; i <= 99; i++)
        {
            randomizedContent.Current.IsSome.Should().BeTrue();
            // this test data setup/expectation is confusing
            randomizedContent.Current.Map(c => c.Id).IfNone(-1).Should().Be(_expected[i - 2]);
            randomizedContent.State.Index.Should().Be(i);

            randomizedContent.MoveNext();
        }
    }

    [Test]
    public void State_Index_Should_Continue_Past_End_Of_Items()
    {
        List<MediaItem> contents = Episodes(10);
        var state = new CollectionEnumeratorState { Index = 10, Seed = KnownSeed };

        var _ = new RandomizedMediaCollectionEnumerator(contents, state);
    }

    private static List<MediaItem> Episodes(int count) =>
        Range(1, count).Map(
                i => (MediaItem)new Episode
                {
                    Id = i,
                    EpisodeMetadata = new List<EpisodeMetadata>
                    {
                        new()
                        {
                            ReleaseDate = new DateTime(2020, 1, i)
                        }
                    }
                })
            .Reverse()
            .ToList();
}