xADDomainController: Added new parameter IsGlobalCatalog (#255)

- Changes to xADDomainController
  - Added new parameter to disable or enable the Global Catalog (GC) (issue #75).
  - Fixed a bug with the parameter `InstallationMediaPath` that it would
    not be added if it was specified in a configuration. Now the parameter
    `InstallationMediaPath` is correctly passed to `Install-ADDSDomainController`.
  - Refactored the resource with major code cleanup and localization.
  - Updated unit tests to latest unit test template, and refactored the
    tests for the function 'Set-TargetResource'.
  - Improved test code coverage.

CHANGELOG.md

@@ -18,6 +18,16 @@
     and [@kungfu71186](https://github.com/kungfu71186)
 - Changes to xADReplicationSiteLink
   - Make use of the new localization helper functions.
+- Changes to xAdDomainController
+  - Added new parameter to disable or enable the Global Catalog (GC)
+    ([issue #75](https://github.com/PowerShell/xActiveDirectory/issues/75)). [Eric Foskett @Merto410](https://github.com/Merto410)
+  - Fixed a bug with the parameter `InstallationMediaPath` that it would
+    not be added if it was specified in a configuration. Now the parameter
+    `InstallationMediaPath` is correctly passed to `Install-ADDSDomainController`.
+  - Refactored the resource with major code cleanup and localization.
+  - Updated unit tests to latest unit test template and refactored the
+    tests for the function 'Set-TargetResource'.
+  - Improved test code coverage.
 
 ## 2.25.0.0
 

DSCResources/MSFT_xADCommon/MSFT_xADCommon.psm1

@@ -1,3 +1,9 @@
+$script:resourceModulePath = Split-Path -Path (Split-Path -Path $PSScriptRoot -Parent) -Parent
+$script:modulesFolderPath = Join-Path -Path $script:resourceModulePath -ChildPath 'Modules'
+
+$script:localizationModulePath = Join-Path -Path $script:modulesFolderPath -ChildPath 'DscResource.LocalizationHelper'
+Import-Module -Name (Join-Path -Path $script:localizationModulePath -ChildPath 'DscResource.LocalizationHelper.psm1')
+
 data localizedString
 {
     # culture="en-US"
@@ -24,6 +30,9 @@ data localizedString
         FoundRestoreTargetInRecycleBin = Found object {0} ({1}) in the recycle bin as {2}. Attempting to restore the object.
         RecycleBinRestoreSuccessful    = Successfully restored object {0} ({1}) from the recycle bin.
         AddingGroupMember              = Adding member '{0}' from domain '{1}' to AD group '{2}'.
+
+        WasExpectingDomainController     = The operating system product type code returned 2, which indicates that this is domain controller, but was unable to retrieve the domain controller object. (ADC0001)
+        FailedEvaluatingDomainController = Could not evaluate if the node is a domain controller. (ADC0002)
 '@
 }
 
@@ -891,3 +900,90 @@ function Add-ADCommonGroupMember
         Add-ADGroupMember @Parameters -Members $Members
     }
 }
+
+<#
+    .SYNOPSIS
+        Returns the domain controller object if the node is a domain controller,
+        otherwise it return $null.
+
+    .PARAMETER DomainName
+        The name of the domain that should contain the domain controller.
+
+    .PARAMETER ComputerName
+        The name of the node to return the domain controller object for.
+        Defaults to $env:COMPUTERNAME.
+
+    .OUTPUTS
+        If the domain controller is not found, an empty object ($null) is returned.
+
+    .NOTES
+        Throws an exception of Microsoft.ActiveDirectory.Management.ADServerDownException
+        if the domain cannot be contacted.
+#>
+function Get-DomainControllerObject
+{
+    [CmdletBinding()]
+    param
+    (
+        [Parameter(Mandatory = $true)]
+        [System.String]
+        $DomainName,
+
+        [Parameter()]
+        [System.String]
+        $ComputerName = $env:COMPUTERNAME,
+
+        [Parameter()]
+        [System.Management.Automation.PSCredential]
+        $Credential
+    )
+
+    <#
+        It is not possible to use `-ErrorAction 'SilentlyContinue` on the
+        cmdlet Get-ADDomainController, it will throw an error regardless.
+    #>
+    try
+    {
+        $getADDomainControllerParameters = @{
+            Filter = 'Name -eq "{0}"' -f $ComputerName
+            Server = $DomainName
+        }
+
+        if ($PSBoundParameters.ContainsKey('Credential'))
+        {
+            $getADDomainControllerParameters['Credential'] = $Credential
+        }
+
+        $domainControllerObject = Get-ADDomainController @getADDomainControllerParameters
+
+        if (-not $domainControllerObject -and (Test-IsDomainController) -eq $true)
+        {
+            $errorMessage = $script:localizedData.WasExpectingDomainController
+            New-InvalidResultException -Message $errorMessage
+        }
+    }
+    catch
+    {
+        $errorMessage = $localizedString.FailedEvaluatingDomainController
+        New-InvalidOperationException -Message $errorMessage -ErrorRecord $_
+    }
+
+    return $domainControllerObject
+}
+
+<#
+    .SYNOPSIS
+        Returns $true if the node is a domain controller, otherwise it returns
+        $false
+#>
+function Test-IsDomainController
+{
+    [CmdletBinding()]
+    param
+    (
+    )
+
+    $operatingSystemInformation = Get-CimInstance -ClassName 'Win32_OperatingSystem'
+
+    return $operatingSystemInformation.ProductType -eq 2
+}