Update locking mechanism and tests to verify locks

Author: markcowl

src/Common/Commands.Common/MetricHelper.cs

@@ -22,8 +22,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
-using System.Net.NetworkInformation;
 using System.Security.Cryptography;
 using System.Text;
 
@@ -62,7 +60,7 @@ public string HashMacAddress
         {
             get
             {
-                lock(_hashMacAddress)
+                lock(_lock)
                 {
                     if (_hashMacAddress == string.Empty)
                     {

src/ResourceManager/Profile/Commands.Profile.Test/TelemetryTests.cs

@@ -48,6 +48,9 @@ public void HashofNullNetworkMACAddressIsNull()
             metricHelper.HashMacAddress = string.Empty;
             try
             {
+                // verify that initialization happens only once and
+                // there are no issues with retrieving the value
+                Assert.Null(metricHelper.HashMacAddress);
                 Assert.Null(metricHelper.HashMacAddress);
                 helper.Verify((f) => f.GetMACAddress(), Times.Once);
             }
@@ -67,6 +70,7 @@ public void HashofEmptyNetworkMACAddressIsNull()
             metricHelper.HashMacAddress = string.Empty;
             try
             {
+                Assert.Null(metricHelper.HashMacAddress);
                 Assert.Null(metricHelper.HashMacAddress);
                 helper.Verify((f) => f.GetMACAddress(), Times.Once);
             }
@@ -86,6 +90,7 @@ public void HashMacAddressOnThrowIsNull()
             metricHelper.HashMacAddress = string.Empty;
             try
             {
+                Assert.Null(metricHelper.HashMacAddress);
                 Assert.Null(metricHelper.HashMacAddress);
                 helper.Verify((f) => f.GetMACAddress(), Times.Once);
             }