title: Implement a list of interfaces during Unit Test using NUnit
body: <p>I'm currently studying C# and I'm quiet stunned over a simple task.
  I have this code to test:</p>
  <pre><code>    public interface IAppointment
  {
      public string PatientName { get; set; }
      public IEnumerable&lt;DateTime&gt; ProposedTimes { get; set; }
      public DateTime? SelectedAppointmentTime { set; }
  }
  
  public static class MedicalScheduler
  {
      public static Dictionary&lt;DateTime, string&gt; Appointments { get; set; } = new Dictionary&lt;DateTime, string&gt;();
      public static List&lt;DateTime&gt; FreeSlots { get; set; } = new List&lt;DateTime&gt;();
  
      public static IEnumerable&lt;Tuple&lt;string, bool&gt;&gt; Schedule(IEnumerable&lt;IAppointment&gt; requests)
      {
          bool slotFound = false;
          foreach (var appointment in requests)
          {
              if (slotFound) continue;
  
              foreach (var times in appointment.ProposedTimes)
              {
                  var freeSlot = FreeSlots.Where(s =&gt; s.Date == times.Date).FirstOrDefault();
  
                  if (freeSlot != null)
                  {
                      slotFound = true;
                      Appointments.Remove(freeSlot);
                      appointment.SelectedAppointmentTime = freeSlot;
                      yield return new Tuple&lt;string, bool&gt;(appointment.PatientName, true);
                  }
              }
  
              yield return new Tuple&lt;string, bool&gt;(appointment.PatientName, false);
          }
      }
  }
  </code></pre>
  <p>And I'm required to test &quot;Schedule&quot; with a certain set of parameters. For example, I need to test it with empty Appointments and FreeList but with a single element in &quot;requests&quot;.
  I think I have understood how to compile a Unit Test and to set the Dictionary and List parameters. But I'm not sure how to create the IEnumerable variable.
  My idea was to create a List of IAppointment(s), but how can I implement the interface in the test unit? I have tried using Moq but I didn't understood how I should use it correctly.</p>
  <p>I'm sorry if the request seems quite confusing, but I don't know how to explain better :)</p>
  <p>Thanks in advance for the help.</p>