C#

{
  "Carrier" : "USPS",
  "US Mail First Class Package",
  "Countries" : [
    {
      "Name" : "United States",
      "Abbr" : "US",
      "States" : [
         "AL",
         "AK",
         "More states ..."
      ],
      "Name" : "Canada",
      "Abbr" : "CA",
      "States" : [
        "BC",
        "ON"
      ]     
    }
}

var results = new List<QuotedShipRates>();
var filter1 = Builders<WEBSITE_SHIPSERVICES>.Filter
    .ElemMatch(c => c.Countries, c => c.Abbr == countryCode);                
var shipRates = await _context.WebsiteShipServices.Find(filter1).ToListAsync();

foreach (var shipRate in shipRates)
{
    results.Add(new QuotedShipRates()
    {
        Name = shipRate.Name,
        Code = shipRate.Code,
        Rate = 5.99M,
        GuaranteedDate = DateTime.Now.AddDays(5)
    });
}  

private void WczytajTabeleSubiekta(string nazwaTabeli, string parametr, string parametr2, out DataTable dt)
        {
            dt = new DataTable();
            try
            {
                OleDbConnection oConn = new OleDbConnection("Provider=VFPOLEDB.1;" + "Data Source=" + subiektPath + @"\DBFS\" + nazwaTabeli + ";Collating Sequence=machine");

                oConn.Open();
                System.Data.OleDb.OleDbCommand oCmd = oConn.CreateCommand();
                oCmd.CommandText = "SELECT " + parametr + " FROM " + subiektPath + @"\DBFS\" + nazwaTabeli + " " + parametr2;
                dt.Load(oCmd.ExecuteReader());
                oConn.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Błąd podczas wczytywania tabeli - " + nazwaTabeli + "\n" + ex.Message.ToString(), "Komunikat");
            }
        }

you will need an event target (e.g. a button), az event list, and events. To solve this problem, create the required data structures for event management, and test every required functionality. For optimal testability, every registered anonymous function must write different text on the console.

Base structure:

Event class, which stores the event function registered by the user (anonymous function). It gives two arguments to the listener function: the event's target (need to use base class, see later), and itself. It stores a public bool member, which if set true, the event chain stops, and further events are not run. This member has a default value of false and can be set from the listener function.

Event list class, which stores events. It can add and remove events. When adding new events, a bool argument defines if the event goes to the beginning or the end of the list. It can run every list in it sequentially with a method, and in the method, it uses a custom iterator for iteration.

Event target class. It has an event list, which gets the event target. It has a method for registering new events.

Button class. Inherits from the event target class. Has a click method, which runs the registered events.

Test cases:

1. Register an event to a new button. See if the button object is available from the event listener function.

2. Register two events to a new button in a way that the events are appended to the end of the list. Register a third event to the beginning of the list. See if they are in correct order.

3. Register three events to a new button. In the second event listener function stop the event chain. Make sure that the third listener function does not run.