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

using System.Collections.Generic;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Scheduling;
using FluentAssertions;
using LanguageExt;
using LanguageExt.UnsafeValueAccess;
using NUnit.Framework;

namespace ErsatzTV.Core.Tests.Scheduling
{
    [TestFixture]
    public class ShuffledMediaCollectionEnumeratorTests
    {
        private readonly List<GroupedMediaItem> _mediaItems = new()
        {
            new GroupedMediaItem(new MediaItem { Id = 1 }, new List<MediaItem>()),
            new GroupedMediaItem(new MediaItem { Id = 2 }, new List<MediaItem>()),
            new GroupedMediaItem(new MediaItem { Id = 3 }, new List<MediaItem>())
        };
        
        [Test]
        public void Peek_Zero_Should_Match_Current()
        {
            var state = new CollectionEnumeratorState { Index = 0, Seed = 0 };
            var enumerator = new ShuffledMediaCollectionEnumerator(_mediaItems, state);

            Option<MediaItem> peek = enumerator.Peek(0);
            Option<MediaItem> current = enumerator.Current;

            peek.IsSome.Should().BeTrue();
            current.IsSome.Should().BeTrue();
            peek.ValueUnsafe().Id.Should().Be(1);
            current.ValueUnsafe().Id.Should().Be(1);
        }
        
        [Test]
        public void Peek_One_Should_Match_Next()
        {
            var state = new CollectionEnumeratorState { Index = 0, Seed = 0 };
            var enumerator = new ShuffledMediaCollectionEnumerator(_mediaItems, state);

            Option<MediaItem> peek = enumerator.Peek(1);

            enumerator.MoveNext();
            Option<MediaItem> next = enumerator.Current;

            peek.IsSome.Should().BeTrue();
            next.IsSome.Should().BeTrue();
            peek.ValueUnsafe().Id.Should().Be(2);
            next.ValueUnsafe().Id.Should().Be(2);
        }
        
        [Test]
        public void Peek_Two_Should_Match_NextNext()
        {
            var state = new CollectionEnumeratorState { Index = 0, Seed = 0 };
            var enumerator = new ShuffledMediaCollectionEnumerator(_mediaItems, state);

            Option<MediaItem> peek = enumerator.Peek(2);

            enumerator.MoveNext();
            enumerator.MoveNext();
            Option<MediaItem> next = enumerator.Current;

            peek.IsSome.Should().BeTrue();
            next.IsSome.Should().BeTrue();
            peek.ValueUnsafe().Id.Should().Be(3);
            next.ValueUnsafe().Id.Should().Be(3);
        }
        
        [Test]
        public void Peek_Three_Should_Match_NextNextNext()
        {
            var state = new CollectionEnumeratorState { Index = 0, Seed = 0 };
            var enumerator = new ShuffledMediaCollectionEnumerator(_mediaItems, state);

            Option<MediaItem> peek = enumerator.Peek(3);

            enumerator.MoveNext();
            enumerator.MoveNext();
            enumerator.MoveNext();
            Option<MediaItem> next = enumerator.Current;

            peek.IsSome.Should().BeTrue();
            next.IsSome.Should().BeTrue();
            peek.ValueUnsafe().Id.Should().Be(2);
            next.ValueUnsafe().Id.Should().Be(2);
        }
    }
}