/// <summary>
/// Adds the supplied share to the watchlist.
/// </summary>
/// <param name="userId">The unique identifier of the user who owns the watchlist.</param>
/// <param name="watchlistId">The unique identifier of the watchlist.</param>
/// <param name="symbol">The share symbol.</param>
public void AddShare(Guid userId, Guid watchlistId, string symbol)
{
Validate.NotEmpty(userId, nameof(userId));
Validate.NotEmpty(watchlistId, nameof(watchlistId));
Validate.NotNullOrWhitespace(symbol, nameof(symbol));
Watchlist watchlist = GetWatchlist(userId, watchlistId);
watchlist.AddShare(symbol);
_watchlistRepository.Save(watchlist);
}
