Vhd: Return bool instead of throwing when Path or ParentPath does not exist

CHANGELOG.md

@@ -7,6 +7,14 @@ For older change log history see the [historic changelog](HISTORIC_CHANGELOG.md)
 
 ## [Unreleased]
 
+- Vhd
+  - `Test-TargetResource` no longer throws when `Path` or `ParentPath` does
+    not exist. Returns the correct boolean based on `Ensure` instead of
+    aborting the configuration. This aligns with the
+    [guidance from Microsoft](https://learn.microsoft.com/powershell/dsc/resources/authoringresourcemof?view=dsc-1.1)
+    that `Test-TargetResource` should return `$false` when the resource is
+    not in the desired state, not throw an exception - Fixes
+    [issue #225](https://github.com/dsccommunity/HyperVDsc/issues/225).
 - HyperVDsc
   - BREAKING CHANGE
     - Renamed _xHyper-V_ to _HyperVDsc - fixes [Issue #69](https://github.com/dsccommunity/HyperVDsc/issues/213).

source/DSCResources/DSC_VHD/DSC_Vhd.psm1

@@ -311,7 +311,8 @@ function Test-TargetResource
     {
         if (!(Test-Path -Path $ParentPath))
         {
-            throw "$ParentPath does not exists"
+            Write-Verbose -Message ($script:localizedData.PathDoesNotExist -f $ParentPath)
+            return ($Ensure -eq 'Absent')
         }
 
         # Check if the generation matches parenting disk
@@ -323,7 +324,8 @@ function Test-TargetResource
 
     if (!(Test-Path -Path $Path))
     {
-        throw "$Path does not exists"
+        Write-Verbose -Message ($script:localizedData.PathDoesNotExist -f $Path)
+        return ($Ensure -eq 'Absent')
     }
 
     # Construct the full path for the vhdFile

source/DSCResources/DSC_VHD/en-US/DSC_Vhd.strings.psd1

@@ -1,2 +1,3 @@
 ConvertFrom-StringData @'
+    PathDoesNotExist = {0} does not exist.
 '@

tests/Unit/DSC_VHD.Tests.ps1

@@ -148,11 +148,27 @@ try
             }
 
             Context 'ParentPath specified' {
-                It 'Should throw when ParentPath does not exist' {
+                It 'Should return $false when ParentPath does not exist and Ensure is Present' {
+                    Mock -CommandName Test-Path -MockWith { $false }
+
+                    $result = Test-TargetResource -Name 'server' -Path 'C:\VMs' -Type 'Differencing' -ParentPath 'c:\boguspath' -Ensure 'Present'
+
+                    $result | Should -BeFalse
+                }
+
+                It 'Should return $true when ParentPath does not exist and Ensure is Absent' {
+                    Mock -CommandName Test-Path -MockWith { $false }
+
+                    $result = Test-TargetResource -Name 'server' -Path 'C:\VMs' -Type 'Differencing' -ParentPath 'c:\boguspath' -Ensure 'Absent'
+
+                    $result | Should -BeTrue
+                }
+
+                It 'Should not throw when ParentPath does not exist' {
                     Mock -CommandName Test-Path -MockWith { $false }
 
                     { Test-TargetResource -Name 'server' -Path 'C:\VMs' -Type 'Differencing' -ParentPath 'c:\boguspath' } |
-                        Should -Throw 'c:\boguspath does not exists'
+                        Should -Not -Throw
                 }
 
                 # "Generation $Generation should match ParentPath extension $($ParentPath.Split('.')[-1])"
@@ -165,11 +181,27 @@ try
             }
 
             Context 'Path does not exist' {
-                It 'Should throw when the path does not exist' {
+                It 'Should return $false when Ensure is Present' {
+                    Mock -CommandName Test-Path -MockWith { $false }
+
+                    $result = Test-TargetResource -Name 'server.vhdx' -Path 'C:\VMs' -Type 'Fixed' -MaximumSizeBytes 1GB -Ensure 'Present'
+
+                    $result | Should -BeFalse
+                }
+
+                It 'Should return $true when Ensure is Absent' {
+                    Mock -CommandName Test-Path -MockWith { $false }
+
+                    $result = Test-TargetResource -Name 'server.vhdx' -Path 'C:\VMs' -Type 'Fixed' -MaximumSizeBytes 1GB -Ensure 'Absent'
+
+                    $result | Should -BeTrue
+                }
+
+                It 'Should not throw' {
                     Mock -CommandName Test-Path -MockWith { $false }
 
                     { Test-TargetResource -Name 'server.vhdx' -Path 'C:\VMs' -Type 'Fixed' -MaximumSizeBytes 1GB } |
-                        Should -Throw 'C:\VMs does not exists'
+                        Should -Not -Throw
                 }
             }