public void PeekBackwardWithinBook_OneBlock_WithinBook()
{
var firstBlock = m_books.First()[0];
var secondBlock = m_books.First()[1];
m_navigator.CurrentBlock = secondBlock;
IEnumerable <Block> result = m_navigator.PeekBackwardWithinBook(1);
Assert.AreEqual(1, result.Count());
Assert.AreEqual(firstBlock, result.First());
}