public void CheckGetLineInEmptyDocument()
        {
            Assert.AreEqual(1, document.Lines.Count);
            List <DocumentLine> lines = new List <DocumentLine>(document.Lines);

            Assert.AreEqual(1, lines.Count);
            DocumentLine line = document.Lines[0];

            Assert.AreSame(line, lines[0]);
            Assert.AreSame(line, document.GetLineByNumber(1));
            Assert.AreSame(line, document.GetLineByOffset(0));
        }