RecordList - a List<T> that supports deep equality and hashing that include items in the list. The equality is does not take order of items into consideration. Useful in combination with C# record types.

RecordList.cs

public sealed class RecordList<T> : List<T>, IEquatable<RecordList<T>>
    where T : IEquatable<T>
{
    private static readonly int EmptyRecordListHashCode = typeof(RecordList<T>).FullName!.GetHashCode(StringComparison.Ordinal);

    public RecordList()
    {
    }

    public RecordList(IEnumerable<T> collection)
        : base(collection)
    {
    }

    public RecordList(int capacity)
        : base(capacity)
    {
    }

    public bool Equals(RecordList<T>? other)
    {
        if (other is null || Count != other.Count)
        {
            return false;
        }

        return GetHashCode() == other.GetHashCode();
    }

    public override bool Equals(object? obj)
        => Equals(obj as RecordList<T>);

    public static bool operator ==(RecordList<T> x, RecordList<T> y) => !(x is null || y is null) && x.Equals(y);

    public static bool operator !=(RecordList<T> x, RecordList<T> y) => !(x == y);

    public override int GetHashCode()
    {
        var hashCode = EmptyRecordListHashCode;

        for (int i = 0; i < Count; i++)
        {
            hashCode += EqualityComparer<T>.Default.GetHashCode(this[i]) * -1521134295;
        }

        return hashCode;
    }

    public override string ToString() => $"[{string.Join(", ", this)}]";
}

public static class EnumerableExtensions
{
    public static RecordList<TSource> ToRecordList<TSource>(this IEnumerable<TSource> source)
        where TSource : IEquatable<TSource>
    {
        ArgumentNullException.ThrowIfNull(source);
        return new RecordList<TSource>(source);
    }
}