VMHardDiskDrive: Return Absent when VM does not exist instead of throwing

CHANGELOG.md

@@ -7,6 +7,11 @@ For older change log history see the [historic changelog](HISTORIC_CHANGELOG.md)
 
 ## [Unreleased]
 
+- VMHardDiskDrive
+  - `Get-TargetResource` no longer throws when the VM does not exist. Returns
+    `Ensure = 'Absent'` so `Test-TargetResource` correctly reports the resource
+    is not in desired state instead of aborting the configuration - Fixes
+    [Issue #223](https://github.com/dsccommunity/HyperVDsc/issues/223).
 - HyperVDsc
   - BREAKING CHANGE
     - Renamed _xHyper-V_ to _HyperVDsc - fixes [Issue #69](https://github.com/dsccommunity/HyperVDsc/issues/213).

source/DSCResources/DSC_VMHardDiskDrive/DSC_VMHardDiskDrive.psm1

@@ -31,6 +31,24 @@ function Get-TargetResource
 
     Assert-Module -ModuleName 'Hyper-V'
 
+    # Check if the VM exists before querying its hard disk drives.
+    # When the VM has not been created yet (e.g., during initial provisioning
+    # with dependsOn), return Absent rather than throwing so that
+    # Test-TargetResource can report the resource is not in desired state.
+    $vm = Get-VM -Name $VMName -ErrorAction SilentlyContinue
+    if ($null -eq $vm)
+    {
+        Write-Verbose -Message ($script:localizedData.VMNotFound -f $VMName)
+        return @{
+            VMName             = $VMName
+            Path               = $null
+            ControllerType     = $null
+            ControllerNumber   = $null
+            ControllerLocation = $null
+            Ensure             = 'Absent'
+        }
+    }
+
     $hardDiskDrive = Get-VMHardDiskDrive -VMName $VMName -ErrorAction Stop |
         Where-Object -FilterScript { $_.Path -eq $Path }
 

source/DSCResources/DSC_VMHardDiskDrive/en-US/DSC_VMHardDiskDrive.strings.psd1

@@ -1,6 +1,7 @@
 ConvertFrom-StringData @'
     DiskFound                    = Found hard disk '{0}' attached to VM '{1}'.
     DiskNotFound                 = Hard disk '{0}' missing from VM '{1}'
+    VMNotFound                   = VM '{0}' not found.
     CheckingDiskIsAttached       = Checking if the disk is already attached to the VM.
     CheckingExistingDiskLocation = Checking if there is an existing disk in the specified location.
     AddingDisk                   = Adding the disk '{0}' to VM '{1}'.

tests/Unit/DSC_VMHardDiskDrive.Tests.ps1

@@ -50,6 +50,7 @@ try
             Mock -CommandName Assert-Module
 
             It 'Should return a [System.Collections.Hashtable] object type' {
+                Mock -CommandName Get-VM { return [PSCustomObject]@{ Name = $testVMName } }
                 Mock -CommandName Get-VMHardDiskDrive { return $stubHardDiskDrive }
 
                 $result = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath
@@ -58,6 +59,7 @@ try
             }
 
             It 'Should return "Present" when hard disk is attached' {
+                Mock -CommandName Get-VM { return [PSCustomObject]@{ Name = $testVMName } }
                 Mock -CommandName Get-VMHardDiskDrive { return $stubHardDiskDrive }
 
                 $result = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath
@@ -66,15 +68,36 @@ try
             }
 
             It 'Should return "Absent" when hard disk is not attached' {
+                Mock -CommandName Get-VM { return [PSCustomObject]@{ Name = $testVMName } }
                 Mock -CommandName Get-VMHardDiskDrive
 
                 $result = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath
 
                 $result.Ensure | Should -Be 'Absent'
             }
 
+            It 'Should return "Absent" when VM does not exist' {
+                Mock -CommandName Get-VM
+                Mock -CommandName Get-VMHardDiskDrive
+
+                $result = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath
+
+                $result.Ensure | Should -Be 'Absent'
+                $result.Path | Should -BeNullOrEmpty
+            }
+
+            It 'Should not call Get-VMHardDiskDrive when VM does not exist' {
+                Mock -CommandName Get-VM
+                Mock -CommandName Get-VMHardDiskDrive
+
+                $null = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath
+
+                Assert-MockCalled -CommandName Get-VMHardDiskDrive -Times 0 -Scope It
+            }
+
             It 'Should assert Hyper-V module is installed' {
                 Mock -CommandName Assert-Module
+                Mock -CommandName Get-VM { return [PSCustomObject]@{ Name = $testVMName } }
                 Mock -CommandName Get-VMHardDiskDrive { return $stubHardDiskDrive }
 
                 $null = Get-TargetResource -VMName $testVMName -Path $testhardDiskPath