anchor.diff:  
       [Test]
       [Ignore]
  +    procedure too_short_isbn;
  +
  +    [Test]
  +    [Ignore]
       procedure isbn_without_check_digit;
   
       [Test]
  
positive.code:   Assert.IsFalse(TIsbn.isValid('3598215078X'));
  end;
  
  procedure ISBNVerifierTest.valid_isbn_number;
  begin
    Assert.IsTrue(TIsbn.isValid('3-598-21508-8'));
  
negative.code:     [Test]
      [Ignore]
      procedure empty_ISBN;
  
      [Test]
      [Ignore]
      procedure input_is_9_characters;
  
      [Test]
      [Ignore]
      procedure invalid_characters_are_not_ignored;
    end;
  
  implementation
  