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

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

@@ -0,0 +1,38 @@
+//
+// 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 Microsoft.SqlTools.ServiceLayer.Utility;
+using Xunit;
+
+namespace Microsoft.SqlTools.Test.Utility
+{
+    public class ValidateTests
+    {
+        [Fact]
+        public void IsWithinRangeTest()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => Validate.IsWithinRange("parameterName", 1, 2, 3));
+        }
+
+        [Fact]
+        public void IsLessThanTest()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => Validate.IsLessThan("parameterName", 2, 1));
+        }
+
+        [Fact]
+        public void IsNotEqualTest()
+        {
+            Assert.Throws<ArgumentException>(() => Validate.IsNotEqual<int>("parameterName", 1, 1));
+        }
+
+        [Fact]
+        public void IsNullOrWhiteSpaceTest()
+        {
+            Assert.Throws<ArgumentException>(() => Validate.IsNotNullOrWhitespaceString("parameterName", null));
+        }
+    }
+}