public void IsNullLetterTileTest()
        {
            LetterTile lt = new LetterTile('n', 0);
            Assert.IsTrue(lt.IsNullLetterTile());

            lt = new LetterTile('A', 1);
            Assert.IsFalse(lt.IsNullLetterTile());
        }
 /// <summary>
 /// Inserts a LetterTile into the LetterTileRack. Throws InvalidLetterTileInsertionException.
 /// </summary>
 /// <param name="letterTileToBeInserted">The LetterTile that is being inserted into the LetterTileRack.</param>
 public void InsertLetterTile(LetterTile letterTileToBeInserted)
 {
     if (this.containedLetterTileSet.Count == 7)
     {
         throw new InvalidLetterTileInsertionException("The insertion of letter tile with LetterValue == " + letterTileToBeInserted.LetterValue +
             " and PointValue == " + letterTileToBeInserted.PointValue + " is invalid. The LetterTileRack is full.");
     }
     else
     {
         // Inserting a null LetterTile is the equivalent of not inserting anything.
         if (!letterTileToBeInserted.IsNullLetterTile())
         {
             this.containedLetterTileSet.Add(letterTileToBeInserted);
         }
     }
 }