public void Contains_EmptyRegister_False()
{
BookRegister register = new BookRegister();
bool actual = register.Contains("1");
Assert.IsFalse(actual);
}
public void Contains_RegisterDoesNotContainBookWithCertainIsbn_False()
{
BookRegister register = new BookRegister();
register.Add(new Book("name", "author", "category", "language", "1999", "123"));
bool actual = register.Contains("1");
Assert.IsFalse(actual);
}