Entity and Value Object Implementations

Entity.cs

public abstract class Entity : IEquatable<Entity>
{
    protected Entity(Guid id)
    {
        Id = id;
    }

    public Guid Id { get; private init; }

    public override bool Equals(object? obj)
    {
        if (obj is null)
        {
            return false;
        }

        if (ReferenceEquals(this, obj))
        {
            return true;
        }

        if (obj.GetType() != GetType())
        {
            return false;
        }

        return Equals((Entity)obj);
    }

    public bool Equals(Entity? other)
    {
        if (other is null)
        {
            return false;
        }

        return ReferenceEquals(this, other) || Id.Equals(other.Id);
    }

    public override int GetHashCode()
    {
        return Id.GetHashCode();
    }

    public static bool operator ==(Entity? left, Entity? right) => Equals(left, right);

    public static bool operator !=(Entity? left, Entity? right) => !Equals(left, right);
}

ValueObject.cs

public abstract class ValueObject : IEquatable<ValueObject>
{
    protected abstract IEnumerable<object> GetEqualityComponents();

    public static bool operator ==(ValueObject? a, ValueObject? b)
    {
        if (a is null && b is null)
        {
            return true;
        }

        if (a is null || b is null)
        {
            return false;
        }

        return a.Equals(b);
    }

    public static bool operator !=(ValueObject? a, ValueObject? b)
    {
        return !(a == b);
    }

    public virtual bool Equals(ValueObject? other)
    {
        return other is not null && ValuesAreEqual(other);
    }

    public override bool Equals(object? obj)
    {
        return obj is ValueObject valueObject && ValuesAreEqual(valueObject);
    }

    public override int GetHashCode()
    {
        return GetEqualityComponents().Aggregate(0, (hashcode, value) => HashCode.Combine(hashcode, value.GetHashCode()));
    }


    private bool ValuesAreEqual(ValueObject valueObject)
    {
        return GetEqualityComponents().SequenceEqual(valueObject.GetEqualityComponents());
    }
}