Disk: Fix Partition MaxSize discrepency - Fixes #181

CHANGELOG.md

@@ -5,6 +5,9 @@
 - Disk:
   - Added `Location` as a possible value for `DiskIdType`. This will select the
     disk based on the `Location` property returned by `Get-Disk`
+  - Maximum size calculation now uses workaround so that
+    Test-TargetResource works properly - workaround for
+    [Issue #181](https://github.com/PowerShell/StorageDsc/issues/181).
 - DiskAccessPath:
   - Added `Location` as a possible value for `DiskIdType`. This will select the
     disk based on the `Location` property returned by `Get-Disk`

DSCResources/MSFTDSC_Disk/MSFTDSC_Disk.psm1

@@ -809,7 +809,21 @@ function Test-TargetResource
     {
         $supportedSize = ($partition | Get-PartitionSupportedSize)
 
-        $Size = $supportedSize.SizeMax
+        <#
+            If the difference in size between the supported partition size
+            and the current partition size is less than 1MB then set the
+            desired partition size to the current size. This will prevent
+            any size difference less than 1MB from trying to contiuously
+            resize. See https://github.com/PowerShell/StorageDsc/issues/181
+        #>
+        if (($supportedSize.SizeMax - $partition.Size) -lt 1MB)
+        {
+            $Size = $partition.Size
+        }
+        else
+        {
+            $Size = $supportedSize.SizeMax
+        }
     }
 
     if ($Size)

DSCResources/MSFTDSC_Disk/README.md

@@ -25,6 +25,8 @@ table for the disk has been created.
 
 ## Known Issues
 
+### Defragsvc Conflict
+
 The 'defragsvc' service ('Optimize Drives') may cause the following errors when
 enabled with this resource. The following error may occur when testing the state
 of the resource:
@@ -41,6 +43,17 @@ this error. Use the `Service` resource in either the 'xPSDesiredStateConfgiurati
 or 'PSDSCResources' resource module to set the 'defragsvc' service is always
 stopped and set to manual start up.
 
+### Null Location
+
 The _Location_ for a disk may be `null` for some types of disk,
 e.g. file-based virtual disks. Physical disks or Virtual disks provided via a
 hypervisor or other hardware virtualization platform should not be affected.
+
+### Maximum Supported Partition Size
+
+On some disks the _maximum supported partition size_ may differ from the actual
+size of a partition created when specifying the maximum size. This difference
+in reported size is always less than **1MB**, so if the reported _maximum supported
+partition size_ is less than **1MB** then the partition will be considered to be
+in the correct state. This is a work around for [this issue](https://windowsserver.uservoice.com/forums/301869-powershell/suggestions/36967870-get-partitionsupportedsize-and-msft-partition-clas)
+that has been reported on user voice and also discussed in [issue #181](https://github.com/PowerShell/StorageDsc/issues/181).

DSCResources/MSFT_DiskAccessPath/README.md

@@ -23,6 +23,8 @@ of disk selection the disk must have been initialized by some other method.
 
 ## Known Issues
 
+### Null Location
+
 The _Location_ for a disk may be `null` for some types of disk,
 e.g. file-based virtual disks. Physical disks or Virtual disks provided via a
 hypervisor or other hardware virtualization platform should not be affected.

DSCResources/MSFT_WaitForDisk/README.md

@@ -22,6 +22,8 @@ of disk selection the disk must have been initialized by some other method.
 
 ## Known Issues
 
+### Null Location
+
 The _Location_ for a disk may be `null` for some types of disk,
 e.g. file-based virtual disks. Physical disks or Virtual disks provided via a
 hypervisor or other hardware virtualization platform should not be affected.

Tests/Integration/MSFTDSC_Disk.Integration.Tests.ps1

@@ -891,6 +891,116 @@ try
             }
         }
         #endregion
+
+        #region Integration Tests for size and maximum size
+        Context 'When maximum size is used, Test-TargetResource needs to report true even though Size and SizeMax are different.' {
+            BeforeAll {
+                # Create a VHD and attach it to the computer
+                $VHDPath = Join-Path -Path $TestDrive `
+                    -ChildPath 'TestDisk.vhd'
+                $null = New-VDisk -Path $VHDPath -SizeInMB 1024 -Initialize
+                $null = Mount-DiskImage -ImagePath $VHDPath -StorageType VHD -NoDriveLetter
+                $diskImage = Get-DiskImage -ImagePath $VHDPath
+                $disk = Get-Disk -Number $diskImage.Number
+                $FSLabelA = 'TestDiskA'
+                $FSLabelB = 'TestDiskB'
+
+                # Get a spare drive letter
+                $lastDrive = ((Get-Volume).DriveLetter | Sort-Object | Select-Object -Last 1)
+                $driveLetterA = [char](([int][char]$lastDrive) + 1)
+                $driveLetterB = [char](([int][char]$lastDrive) + 2)
+            }
+
+            Context "When using fixed size Disk Number $($disk.Number)" {
+                It 'Should compile and apply the MOF without throwing' {
+                    {
+                        # This is to pass to the Config
+                        $configData = @{
+                            AllNodes = @(
+                                @{
+                                    NodeName       = 'localhost'
+                                    DriveLetter    = $driveLetterA
+                                    DiskId         = $disk.Number
+                                    DiskIdType     = 'Number'
+                                    PartitionStyle = 'GPT'
+                                    FSLabel        = $FSLabelA
+                                    Size           = 100MB
+                                }
+                            )
+                        }
+
+                        & "$($script:DSCResourceName)_Config" `
+                            -OutputPath $TestDrive `
+                            -ConfigurationData $configData
+
+                        Start-DscConfiguration `
+                            -Path $TestDrive `
+                            -ComputerName localhost `
+                            -Wait `
+                            -Verbose `
+                            -Force `
+                            -ErrorAction Stop
+                    } | Should -Not -Throw
+                }
+
+                It 'Should be able to call Get-DscConfiguration without throwing' {
+                    { $script:currentConfiguration = Get-DscConfiguration -Verbose -ErrorAction Stop } | Should -Not -Throw
+                }
+
+                It 'Should have set the resource and size should match' {
+                    $current = $script:currentConfiguration | Where-Object -FilterScript {
+                        $_.ConfigurationName -eq "$($script:DSCResourceName)_Config"
+                    }
+                    $current.Size         | Should -Be 100MB
+                }
+            }
+
+            Context "When using maximum size for new volume on Disk Number $($disk.Number)" {
+                It 'Should compile and apply the MOF without throwing' {
+                    {
+                        # This is to pass to the Config
+                        $configData = @{
+                            AllNodes = @(
+                                @{
+                                    NodeName       = 'localhost'
+                                    DriveLetter    = $driveLetterA
+                                    DiskId         = $disk.Number
+                                    DiskIdType     = 'Number'
+                                    PartitionStyle = 'GPT'
+                                    FSLabel        = $FSLabelA
+                                }
+                            )
+                        }
+
+                        & "$($script:DSCResourceName)_Config" `
+                            -OutputPath $TestDrive `
+                            -ConfigurationData $configData
+
+                        Start-DscConfiguration `
+                            -Path $TestDrive `
+                            -ComputerName localhost `
+                            -Wait `
+                            -Verbose `
+                            -Force `
+                            -ErrorAction Stop
+                    } | Should -Not -Throw
+                }
+
+                It 'Should be able to call Get-DscConfiguration without throwing' {
+                    { $script:currentConfiguration = Get-DscConfiguration -Verbose -ErrorAction Stop } | Should -Not -Throw
+                }
+
+                It 'Test-DscConfiguration should return True, indicating that partition size instead of SizeMax was used' {
+                    Test-DscConfiguration | Should -Be $true
+                }
+            }
+
+            AfterAll {
+                Dismount-DiskImage -ImagePath $VHDPath -StorageType VHD
+                Remove-Item -Path $VHDPath -Force
+            }
+        }
+        #endregion
     }
 }
 finally

Tests/Unit/MSFTDSC_Disk.Tests.ps1

@@ -2667,7 +2667,8 @@ try
                     -MockWith {
                         return @{
                             SizeMin = 0
-                            SizeMax = $script:mockedPartition.Size + 1024
+                            # Adding >1MB, otherwise workaround for wrong SizeMax is triggered
+                            SizeMax = $script:mockedPartition.Size + 1.1MB
                         }
                     } `
                     -Verifiable
@@ -2727,7 +2728,8 @@ try
                     -MockWith {
                         return @{
                             SizeMin = 0
-                            SizeMax = $script:mockedPartition.Size + 1024
+                            # Adding >1MB, otherwise workaround for wrong SizeMax is triggered
+                            SizeMax = $script:mockedPartition.Size + 1.1MB
                         }
                     } `
                     -Verifiable
@@ -2764,6 +2766,59 @@ try
                 }
             }
 
+            Context 'When testing matching partition size with a less than 1MB difference in desired size and with AllowDestructive and without Size specified using Disk Number' {
+                # verifiable (should be called) mocks
+                Mock `
+                    -CommandName Get-DiskByIdentifier `
+                    -ParameterFilter $script:parameterFilter_MockedDisk0Number `
+                    -MockWith { $script:mockedDisk0Gpt } `
+                    -Verifiable
+
+                Mock `
+                    -CommandName Get-Partition `
+                    -MockWith { $script:mockedPartition } `
+                    -Verifiable
+
+                Mock `
+                    -CommandName Get-PartitionSupportedSize `
+                    -MockWith {
+                        return @{
+                            SizeMin = 0
+                            SizeMax = $script:mockedPartition.Size + 0.98MB
+                        }
+                    } `
+                    -Verifiable
+                Mock -CommandName Get-Volume -Verifiable
+                Mock -CommandName Get-CimInstance -Verifiable
+
+                $script:result = $null
+
+                It 'Should not throw an exception' {
+                    {
+                        $script:result = Test-TargetResource `
+                            -DiskId $script:mockedDisk0Gpt.Number `
+                            -DriveLetter $script:testDriveLetter `
+                            -AllocationUnitSize 4096 `
+                            -AllowDestructive $true `
+                            -Verbose
+                    } | Should -Not -Throw
+                }
+
+                It 'Should be true' {
+                    $script:result | Should -Be $true
+                }
+
+                It 'Should call the correct mocks' {
+                    Assert-VerifiableMock
+                    Assert-MockCalled -CommandName Get-DiskByIdentifier -Exactly -Times 1 `
+                        -ParameterFilter $script:parameterFilter_MockedDisk0Number
+                    Assert-MockCalled -CommandName Get-Partition -Exactly -Times 1
+                    Assert-MockCalled -CommandName Get-PartitionSupportedSize -Exactly -Times 1
+                    Assert-MockCalled -CommandName Get-Volume -Exactly -Times 1
+                    Assert-MockCalled -CommandName Get-CimInstance -Exactly -Times 1
+                }
+            }
+
             Context 'When testing mismatched AllocationUnitSize using Disk Number' {
                 # verifiable (should be called) mocks
                 Mock `