FakeDbSet for mocking / moq

public class FakeDbSet<T> : DbSet<T>, IQueryable, IEnumerable<T> where T : class {
    List<T> _data;

    public FakeDbSet(List<T> items=null) {
        _data = items ?? new List<T>();
    }

    public void Clear() {
        _data = new();
    }

    public override T Find(params object[] keyValues) {
        throw new NotImplementedException("Derive from FakeDbSet<T> and override Find");
    }

    public override EntityEntry<T> Add(T item) {
        _data.Add(item);
        return item as EntityEntry<T>;
    }

    public override EntityEntry<T> Remove(T item) {
        _data.Remove(item);
        return item as EntityEntry<T>;
    }

    public override EntityEntry<T> Attach(T item) {
        return null;
    }

    public T Detach(T item) {
        _data.Remove(item);
        return item;
    }

    public T Create() {
        return Activator.CreateInstance<T>();
    }

    public TDerivedEntity Create<TDerivedEntity>() where TDerivedEntity : class, T {
        return Activator.CreateInstance<TDerivedEntity>();
    }

    public List<T> Local {
        get { return _data; }
    }

    public override IEntityType EntityType => throw new NotImplementedException();

    public override void AddRange(IEnumerable<T> entities) {
        _data.AddRange(entities);
    }

    public override void RemoveRange(IEnumerable<T> entities) {
        for (int i = entities.Count() - 1; i >= 0; i--) {
            T entity = entities.ElementAt(i);
            if (_data.Contains(entity)) {
                Remove(entity);
            }
        }

    }

    Type IQueryable.ElementType {
        get { return _data.AsQueryable().ElementType; }
    }

    Expression IQueryable.Expression {
        get { return _data.AsQueryable().Expression; }
    }

    IQueryProvider IQueryable.Provider {
        get { return _data.AsQueryable().Provider; }
    }

    IEnumerator IEnumerable.GetEnumerator() {
        return _data.GetEnumerator();
    }

    IEnumerator<T> IEnumerable<T>.GetEnumerator() {
        return _data.GetEnumerator();
    }

}