using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    private record Outcome

    {

        public int Id { get; init; }

        public List<string> Errors { get; init; } = new List<string>();

    }

    public static void Main()

    {

        int[] ids = new int[] { 1, 2, 3 };

        IReadOnlyCollection<Outcome> outcomes = ids.Select(id => new Outcome() { Id = id }).ToList();

        int counter = 0;

        foreach(Outcome outcome in outcomes)

        {

            outcome.Errors.AddRange(Enumerable.Range(counter, 2).Select(c => $"Test - {outcome.Id}:{++counter}"));

        }

        foreach(Outcome outcome in outcomes)

        {

            Console.WriteLine($"{outcome.Id}: {string.Join(", ", outcome.Errors)}");

        }

    }

}