Fixing up mof compilation test script to set PSMODULEPATH properly

test/powershell/Modules/PSDesiredStateConfiguration/MOF-Compilation.Tests.ps1

@@ -1,13 +1,15 @@
-$originalPSModulePath = $env:PSModulePath
-
-try
-{
-    $env:DSC_HOME = Join-Path -Path (Join-Path -Path $PSScriptRoot -ChildPath assets) -ChildPath dsc
-#   $env:PSMODULEPATH = $env:PSMODULEPATH + ";" + $env:DEVPATH + "Modules"
-#    $env:PSModulePath = "$($env:DEVPATH)\Modules"
-
 Describe "DSC MOF Compilation" -tags "CI" {
 
+    AfterAll {
+        $env:PSMODULEPATH = $_modulePath
+    }
+    BeforeAll {
+        $env:DSC_HOME = Join-Path -Path (Join-Path -Path $PSScriptRoot -ChildPath assets) -ChildPath dsc
+        $_modulePath = $env:PSMODULEPATH
+        $powershellexe = (get-process -pid $PID).MainModule.FileName
+        $env:PSMODULEPATH = join-path ([io.path]::GetDirectoryName($powershellexe)) Modules
+    }
+
     It "Should be able to compile a MOF from a basic configuration" -Skip:$IsWindows {
         [Scriptblock]::Create(@"
         configuration DSCTestConfig
@@ -162,8 +164,3 @@ Describe "DSC MOF Compilation" -tags "CI" {
     }
 
 }
-}
-finally
-{
-    $env:PSModulePath = $originalPSModulePath
-}