Recyclable.Collections/Recyclable.CollectionsTests/RecyclablePriorityQueueTests.cs

using FluentAssertions;
using Recyclable.Collections;

namespace Recyclable.CollectionsTests
{
    public class RecyclablePriorityQueueTests
    {
        private static readonly int[] _testData = new[] { 4, 1, 3, 2, 5 };

        [Fact]
        public void DequeueShouldReturnItemsInSortedOrder()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            foreach (var item in _testData)
            {
                queue.Enqueue(item);
            }

            var result = new List<int>();
            while (queue.LongCount > 0)
            {
                result.Add(queue.Dequeue());
            }

            _ = result.Should().BeInAscendingOrder();
        }

        [Fact]
        public void ShouldBeEmptyWhenNotInitialized()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            _ = queue.Should().BeEmpty();
            _ = queue.LongCount.Should().Be(0);
        }

        [Fact]
        public void ShouldBeEmptyAfterClear()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            foreach (var item in _testData)
            {
                queue.Enqueue(item);
            }

            queue.Clear();
            _ = queue.Should().BeEmpty();
        }

        [Fact]
        public void DequeueShouldThrowWhenNoElements()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            _ = Assert.Throws<ArgumentOutOfRangeException>(() => queue.Dequeue());
        }

        [Fact]
        public void AddRangeSpanShouldAddItemsInSortedOrder()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            queue.AddRange((ReadOnlySpan<int>)_testData);

            var result = new List<int>();
            while (queue.LongCount > 0)
            {
                result.Add(queue.Dequeue());
            }

            _ = result.Should().Equal(_testData.Order());
        }

        [Fact]
        public void AddRangeSpanShouldDoNothingWhenEmpty()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            queue.AddRange(ReadOnlySpan<int>.Empty);
            _ = queue.Should().BeEmpty();
        }

        [Fact]
        public void AddRangeSpanShouldNotOverrideItems()
        {
            using var queue = new RecyclablePriorityQueue<int>();
            queue.AddRange((ReadOnlySpan<int>)_testData);
            queue.AddRange((ReadOnlySpan<int>)_testData);

            var expected = _testData.Concat(_testData).Order().ToArray();
            var result = new List<int>();
            while (queue.LongCount > 0)
            {
                result.Add(queue.Dequeue());
            }

            _ = result.Should().Equal(expected);
        }

        [Fact]
        public void AddRangeShouldAcceptNulls()
        {
            using var queue = new RecyclablePriorityQueue<long?>();
            queue.AddRange(new long?[] { null, 1 });
            _ = queue.Should().HaveCount(2).And.Contain((long?)null);
        }

    }
}