Packaging: simplify building an installable package for Windows (#5871)

This is the continuation of PR 5499 that had to be abandoned due to a fatal merge conflict and I did not want to risk accidentally reverting recent fixes.

    Remove unnecessary/unused default for productGuid because it always gets a new Guid when being called from Start-PSPackage
    Add defaults for required files but also add extra path validation attribute
    Rename ProductGuid to ProductCode

assets/Product.wxs

@@ -5,7 +5,7 @@
   <!-- TBD:Point to the actual release -->
   <?define InfoURL="https://github.com/PowerShell/PowerShell" ?>
   <?define ProductName = "$(env.ProductName)" ?>
-  <?define ProductGuid = "$(env.ProductGuid)" ?>
+  <?define ProductCode = "$(env.ProductCode)" ?>
   <!-- UpgradeCode GUID MUST REMAIN SAME THROUGHOUT ALL VERSIONS, otherwise, updates won't occur. -->
   <?if $(sys.BUILDARCH)=x64?>
     <?define UpgradeCode = "31ab5147-9a97-4452-8443-d9709f0516e1" ?>
@@ -24,8 +24,8 @@
   <!-- Explorer context submenu entries. The ampersand denotes the keyboard shortcut. -->
   <?define ExplorerContextSubMenuDialogText = "Open &here"?>
   <?define ExplorerContextSubMenuElevatedDialogText = "Open here as &Administrator"?>
-  <!-- The ProductCode is Product Id: http://wixtoolset.org/documentation/manual/v3/xsd/wix/product.html -->
-  <Product Id="$(var.ProductGuid)" Name="$(var.ProductSemanticVersionWithName)-$(sys.BUILDARCH)" Language="1033" Version="$(var.ProductVersion)" Manufacturer="Microsoft Corporation" UpgradeCode="$(var.UpgradeCode)">
+  <!-- The ProductCode is Product Id and needs to be unique for every PowerShell version to allow SxS install: http://wixtoolset.org/documentation/manual/v3/xsd/wix/product.html -->
+  <Product Id="$(var.ProductCode)" Name="$(var.ProductSemanticVersionWithName)-$(sys.BUILDARCH)" Language="1033" Version="$(var.ProductVersion)" Manufacturer="Microsoft Corporation" UpgradeCode="$(var.UpgradeCode)">
     <!-- Properties About The Package -->
     <Package Id="*" Keywords="Installer" Platform="$(sys.BUILDARCH)" InstallerVersion="200" Compressed="yes" InstallScope="perMachine" Description="PowerShell package" Comments="PowerShell for every system" />
     <!-- Add PowerShell icon for executable -->

build.psm1

@@ -2052,6 +2052,16 @@ function Get-PackageVersionAsMajorMinorBuildRevision
     $packageVersion
 }
 
+<#
+    .Synopsis
+        Creates a Windows installer MSI package and assumes that the binaries are already built using 'Start-PSBuild'.
+        This only works on a Windows machine due to the usage of WiX.
+    .EXAMPLE
+        # This example shows how to produce a Debug-x64 installer for development purposes.
+        cd $RootPathOfPowerShellRepo
+        Import-Module .\build.psm1; Import-Module .\tools\packaging\packaging.psm1
+        New-MSIPackage -Verbose -ProductCode (New-Guid) -ProductSourcePath '.\src\powershell-win-core\bin\Debug\netcoreapp2.0\win7-x64\publish' -ProductTargetArchitecture x64 -ProductVersion '1.2.3'
+#>
 function New-MSIPackage
 {
     [CmdletBinding()]
@@ -2069,9 +2079,10 @@ function New-MSIPackage
         [ValidateNotNullOrEmpty()]
         [string] $ProductVersion,
 
-        # Product Guid needs to change for every version to support SxS install
+        # The ProductCode property is a unique identifier for the particular product release
+        [Parameter(Mandatory = $true)]
         [ValidateNotNullOrEmpty()]
-        [string] $ProductGuid = 'a5249933-73a1-4b10-8a4c-13c98bdc16fe',
+        [string] $ProductCode,
 
         # Source Path to the Product Files - required to package the contents into an MSI
         [Parameter(Mandatory = $true)]
@@ -2080,17 +2091,18 @@ function New-MSIPackage
 
         # File describing the MSI Package creation semantics
         [ValidateNotNullOrEmpty()]
+        [ValidateScript( {Test-Path $_})]
         [string] $ProductWxsPath = "$PSScriptRoot\assets\Product.wxs",
 
         # Path to Assets folder containing artifacts such as icons, images
-        [Parameter(Mandatory = $true)]
         [ValidateNotNullOrEmpty()]
-        [string] $AssetsPath,
+        [ValidateScript( {Test-Path $_})]
+        [string] $AssetsPath = "$PSScriptRoot\assets",
 
         # Path to license.rtf file - for the EULA
-        [Parameter(Mandatory = $true)]
         [ValidateNotNullOrEmpty()]
-        [string] $LicenseFilePath,
+        [ValidateScript( {Test-Path $_})]
+        [string] $LicenseFilePath = "$PSScriptRoot\assets\license.rtf",
 
         # Architecture to use when creating the MSI
         [Parameter(Mandatory = $true)]
@@ -2137,7 +2149,7 @@ function New-MSIPackage
     [Environment]::SetEnvironmentVariable("ProductSourcePath", $ProductSourcePath, "Process")
     # These variables are used by Product.wxs in assets directory
     [Environment]::SetEnvironmentVariable("ProductName", $ProductName, "Process")
-    [Environment]::SetEnvironmentVariable("ProductGuid", $ProductGuid, "Process")
+    [Environment]::SetEnvironmentVariable("ProductCode", $ProductCode, "Process")
     [Environment]::SetEnvironmentVariable("ProductVersion", $ProductVersion, "Process")
     [Environment]::SetEnvironmentVariable("ProductSemanticVersion", $ProductSemanticVersion, "Process")
     [Environment]::SetEnvironmentVariable("ProductVersionWithName", $productVersionWithName, "Process")

tools/packaging/packaging.psm1

@@ -242,8 +242,8 @@ function Start-PSPackage {
                     ProductVersion = $Version
                     AssetsPath = "$PSScriptRoot\..\..\assets"
                     LicenseFilePath = "$PSScriptRoot\..\..\assets\license.rtf"
-                    # Product Guid needs to be unique for every PowerShell version to allow SxS install
-                    ProductGuid = New-Guid
+                    # Product Code needs to be unique for every PowerShell version since it is a unique identifier for the particular product release
+                    ProductCode = New-Guid
                     ProductTargetArchitecture = $TargetArchitecture
                     Force = $Force
                 }