Include ManagedBatchParser tests to improve code coverage (#793)

* Include ManagedBatchParser test to improve code coverage

* Fix some failing test cases and revert appveyor.yml

test/Microsoft.SqlTools.ManagedBatchParser.IntegrationTests/BatchParser/TestVariableResolver.cs

@@ -0,0 +1,36 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.SqlTools.ServiceLayer.BatchParser;
+using Microsoft.SqlTools.ServiceLayer.BatchParser.ExecutionEngineCode;
+
+namespace Microsoft.SqlTools.ManagedBatchParser.UnitTests.BatchParser
+{
+    internal sealed class TestVariableResolver : IVariableResolver
+    {
+        private StringBuilder outputString;
+        private BatchParserSqlCmd batchParserSqlCmd;
+
+        public TestVariableResolver(StringBuilder outputString)
+        {
+            this.outputString = outputString;
+            batchParserSqlCmd = new BatchParserSqlCmd();
+        }
+
+        public string GetVariable(PositionStruct pos, string name)
+        {
+            return batchParserSqlCmd.GetVariable(pos, name);
+        }
+
+        public void SetVariable(PositionStruct pos, string name, string value)
+        {
+            outputString.AppendFormat("Setting variable {0} to [{1}]\n", name, value);
+            batchParserSqlCmd.SetVariable(pos, name, value);
+        }
+    }
+}