Perf Test fixing bugs and Update command (#155)

* Fixed some bugs caused by rafactoring

* Verifying a test db is created before running the tests

test/Microsoft.SqlTools.ServiceLayer.PerfTests/CreateTestDbAttribute.cs

@@ -0,0 +1,39 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Reflection;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer.TestDriver.Utility;
+using Xunit.Sdk;
+
+namespace Microsoft.SqlTools.ServiceLayer.PerfTests
+{
+    /// <summary>
+    /// The attribute for each test to create the test db before the test starts
+    /// </summary>
+    public class CreateTestDbAttribute : BeforeAfterTestAttribute
+    {
+        public CreateTestDbAttribute(TestServerType serverType)
+        {
+            ServerType = serverType;
+        }
+
+        public CreateTestDbAttribute(int serverType)
+        {
+            ServerType = (TestServerType)serverType;
+        }
+
+        public TestServerType ServerType { get; set; }
+        public override void Before(MethodInfo methodUnderTest)
+        {
+            Task task = Common.CreateTestDatabase(ServerType);
+            task.Wait();
+        }
+
+        public override void After(MethodInfo methodUnderTest)
+        {
+        }
+    }
+}