Add tests to improve code coverage (#187)

* DbColumn and ReliableConnection tests

* More retry connection tests

* More tests

* Fix broken peek definition integration tests

* Fix test bug

* Add a couple batch tests

* Add some more tests

* More tests for code coverage.

* Validation and Diagnostic tests

* A few more tests

* A few mote test changes.

* Update file path tests to run on Windows only

src/Microsoft.SqlTools.ServiceLayer/LanguageServices/ScriptDocumentInfo.cs

@@ -92,7 +92,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices.Completion
         /// <summary>
         /// The token text in the file content used for completion list
         /// </summary>
-        public string TokenText
+        public virtual string TokenText
         {
             get
             {