MSI: update path with proper value (PowerShell#6441)

MSI: update path with proper value
- Add verification that path is updated

assets/Product.wxs

@@ -165,7 +165,7 @@
             </Component>
             <!-- add ourselves to %PATH% so pwsh.exe can be started from Windows PowerShell or cmd.exe -->
             <Component Id="SetPath" Guid="{9dbb7763-7baf-48e7-b025-3bdedcb0632f}" KeyPath="yes">
-              <Environment Id="PATH" Action="set" Name="PATH" Part="last" Permanent="no" System="yes" Value="[$(var.ProductVersionWithName)]"/>
+              <Environment Id="PATH" Action="set" Name="PATH" Part="last" Permanent="no" System="yes" Value="[$(var.ProductDirectoryName)]"/>
             </Component>
             <!-- Explorer context menu with 2 submenus to open PowerShell normally or as an Administator.
                  See https://blogs.msdn.microsoft.com/andrew_richards/2017/03/01/enhancing-the-open-command-prompt-here-shift-right-click-context-menu-experience/ for details -->

tools/appveyor.psm1

@@ -486,6 +486,16 @@ function Invoke-AppveyorFinish
             $preReleaseVersion = "$previewPrefix-$previewLabel.$env:APPVEYOR_BUILD_NUMBER"
         }
 
+        # Save any PowerShell paths, so we can exclude them
+        # When we verify we updated the path
+        $beforePath = @(([System.Environment]::GetEnvironmentVariable('PATH','MACHINE')) -split ';' |
+            Where-Object {$_ -like '*files\powershell*'})
+
+        foreach($pathPart in $beforePath)
+        {
+            Write-Log "Found existing PowerShell path: $pathPart"
+        }
+
         # Smoke Test MSI installer
         Write-Log "Smoke-Testing MSI installer"
         $msi = $artifacts | Where-Object { $_.EndsWith(".msi")}
@@ -499,6 +509,15 @@ function Invoke-AppveyorFinish
         }
         Write-Log "MSI smoke test was successful"
 
+        # Verify path was updated by MSI
+        $psPath = ([System.Environment]::GetEnvironmentVariable('PATH','MACHINE')) -split ';' |
+            Where-Object {$_ -like '*files\powershell*' -and $_ -notin $beforePath}
+
+        if(!$psPath)
+        {
+            throw "MSI did not add powershell to path"
+        }
+
         # only publish assembly nuget packages if it is a daily build and tests passed
         if((Test-DailyBuild) -and $env:TestPassed -eq 'True')
         {