public void ExtractLine()
        {
            var text =
                "0123\n" +
                "\n" +
                "0";

            var doc = new TextDocument(text, TestCommon.UriMock);

            Assert.AreEqual("0123\n", doc.ExtractLine(0));
            Assert.AreEqual("0123\n", doc.ExtractLine(1));
            Assert.AreEqual("0123\n", doc.ExtractLine(4));
            Assert.AreEqual("\n", doc.ExtractLine(5));
            Assert.AreEqual("0", doc.ExtractLine(6));
        }