ValidateAssignmentAttribute.cs

namespace Core.Attributes
{
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Linq;
    using System.Reflection;
    
    [AttributeUsage(AttributeTargets.Field)]
    public sealed class ValidateAssignmentAttribute : Attribute
    {
    }

    public static class ValidateAssignmentExtensions
    {
        public static void ValidateAssignments(this UnityEngine.Object o)
        {
#if UNITY_EDITOR
            IEnumerable<FieldInfo> properties = o.GetType().GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                .Where(prop => Attribute.IsDefined(prop, typeof(ValidateAssignmentAttribute)));

            foreach (FieldInfo field in properties)
            {
                object fieldValue = field.GetValue(o);

                bool logNotAssigned = fieldValue switch
                {
                    IList list => list.Count <= 0,
                    ICollection collection => collection.Count <= 0,
                    UnityEngine.Object unityObject => !unityObject,
                    _ => fieldValue == null
                };

                if (logNotAssigned)
                {
                    Debug.Log($"{field.Name} not found.");
                }
            }
#endif
        }
    }
}