From a21d0d6cd3c19095eb6301790cbabe69815d2689 Mon Sep 17 00:00:00 2001
From: Miodrag Milic <miodrag.milic@gmail.com>
Date: Mon, 22 May 2017 21:23:33 +0200
Subject: [PATCH] added whatif package

---
 _scripts/whatif.ps1 | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 _scripts/whatif.ps1

diff --git a/_scripts/whatif.ps1 b/_scripts/whatif.ps1
new file mode 100644
index 0000000..1f51208
--- /dev/null
+++ b/_scripts/whatif.ps1
@@ -0,0 +1,40 @@
+<#
+This script implements WhatIf functionality. When you use it, it will 
+    - backup a package prior a call to update
+    - save updater output to another folder
+    - restore an original package after update finishes
+
+Use it by adding a switch parameter to update.ps1 and surrounding update
+by backup and restore functions:
+
+    param( [switch]$WhatIf )
+
+    ...
+    
+    backup 
+    update ...
+    restore
+
+#>
+
+function backup()  { 
+    if (!$WhatIf) { return }
+    Write-Warning "WhatIf passed - package files will not be changed"
+
+    $packageName = Split-Path -Leaf $MyInvocation.PSScriptRoot
+    $d = "$Env:TEMP\au\$packageName"
+
+    rm $d\* -Recurse -ea 0
+    cp . $d\_backup -Recurse 
+}
+
+function restore() { 
+    $packageName = Split-Path -Leaf $MyInvocation.PSScriptRoot
+    $d = "$Env:TEMP\au\$packageName"
+
+    cp . $d\_output -Recurse 
+    rm .\* -Recurse
+    cp $d\_backup\* . -Recurse 
+
+    Write-Warning "Package saved to: $d\_output"
+}
\ No newline at end of file