Add text utils unit tests and parameter comments. (#192)

* Add unit tests for PositionOfCursor

* Add unit tests for PositionOfCursor

test/Microsoft.SqlTools.ServiceLayer.Test/Utility/TextUtilitiesTests.cs

@@ -0,0 +1,40 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.ServiceLayer.Utility;
+using Xunit;
+
+namespace Microsoft.SqlTools.Test.Utility
+{
+    /// <summary>
+    /// Tests for the TextUtilitiesTests class
+    /// </summary>
+    public class TextUtilitiesTests
+    {
+        [Fact]
+        public void PositionOfCursorFirstLine()
+        {
+            string sql = "EXEC sys.fn_isrolemember ";
+
+            int prevNewLine;
+            int cursorPosition = TextUtilities.PositionOfCursor(sql, 0, sql.Length, out prevNewLine);
+
+            Assert.Equal(prevNewLine, 0);
+            Assert.Equal(cursorPosition, sql.Length);
+        }
+
+        [Fact]
+        public void PositionOfCursorSecondLine()
+        {
+            string sql = "--lineone\nEXEC sys.fn_isrolemember ";
+
+            int prevNewLine;
+            int cursorPosition = TextUtilities.PositionOfCursor(sql, 1, 15, out prevNewLine);
+
+            Assert.Equal(prevNewLine, 10);
+            Assert.Equal(cursorPosition, 25);
+        }
+    }
+}