public void AddTheSameObjectTest()
{
Reader reader = new Reader("Dominik", "Karski");
Assert.AreEqual(repository.GetAllReaders().Count(), 4);
repository.AddReader(reader);
Assert.AreNotEqual(repository.GetAllReaders().Count(), 5);
BookDescription book = new BookDescription("Metro 2033", "Dmitry Glukhovsky", "Insignis");
var count = repository.GetAllBookDescriptions().Count();
Assert.AreEqual(count, 5);
repository.AddBookDescription(book);
repository.AddBookDescription(book);
repository.AddBookDescription(book);
Assert.AreEqual(count, 5);
count = repository.GetAllBookDescriptions().Count();
Assert.AreNotEqual(count, 6);
Assert.AreEqual(repository.GetAllBookCopies().Count(), 5);
repository.AddBookCopy(repository.GetBookCopy(0));
Assert.AreEqual(repository.GetAllBookCopies().Count(), 5);
Assert.AreEqual(repository.GetAllBookEvents().Count(), 7);
repository.AddBookEvent(repository.GetBookEvent(0));
Assert.AreEqual(repository.GetAllBookEvents().Count(), 7);
}