Fix race in telemetry msbuild arg tests

Author: nguerrera

test/dotnet-msbuild.Tests/GivenDotnetMSBuildBuildsProjects.cs

@@ -7,6 +7,7 @@
 using System.Reflection;
 using System.Runtime.InteropServices;
 using FluentAssertions;
+using Microsoft.DotNet.Cli;
 using Microsoft.DotNet.Configurer;
 using Microsoft.DotNet.Tools.MSBuild;
 using Microsoft.DotNet.Tools.Test.Utilities;
@@ -17,6 +18,9 @@
 using System.Diagnostics;
 using System.Threading;
 
+// There are tests which modify static Telemetry.CurrentSessionId and they cannot run in parallel
+[assembly: CollectionBehavior(DisableTestParallelization = true)]
+
 namespace Microsoft.DotNet.Cli.MSBuild.Tests
 {
     public class GivenDotnetMSBuildBuildsProjects : TestBase
@@ -127,7 +131,7 @@ public void WhenTelemetryIsEnabledTheLoggerIsAddedToTheCommandLine()
         {
             Telemetry telemetry;
             string[] allArgs = GetArgsForMSBuild(() => true, out telemetry);
-            // telemetry will still be disabled if environmental variable is set
+            // telemetry will still be disabled if environment variable is set
             if (telemetry.Enabled)
             {
                 allArgs.Should().NotBeNull();
@@ -158,6 +162,7 @@ private string[] GetArgsForMSBuild(Func<bool> sentinelExists)
 
         private string[] GetArgsForMSBuild(Func<bool> sentinelExists, out Telemetry telemetry)
         {
+            Telemetry.CurrentSessionId = null; // reset static session id modified by telemetry constructor
             telemetry = new Telemetry(new MockNuGetCacheSentinel(sentinelExists));
 
             MSBuildForwardingApp msBuildForwardingApp = new MSBuildForwardingApp(Enumerable.Empty<string>());