functions/groups/Test-TmfGroup.ps1

function Test-TmfGroup
{
    <#
        .SYNOPSIS
            Test desired configuration against a Tenant.
        .DESCRIPTION
            Compare current configuration of a resource type with the desired configuration.
            Return a result object with the required changes and actions.
    #>

    [CmdletBinding()]
    Param (
        [System.Management.Automation.PSCmdlet]
        $Cmdlet = $PSCmdlet
    )
    
    begin
    {
        Test-GraphConnection -Cmdlet $Cmdlet
        $componentName = "groups"
        $tenant = Get-MgOrganization -Property displayName, Id        
    }
    process
    {
        foreach ($definition in $script:desiredConfiguration[$componentName]) {
            foreach ($property in $definition.Properties()) {
                if ($definition.$property.GetType().Name -eq "String") {
                    $definition.$property = Resolve-String -Text $definition.$property
                }
            }

            $result = @{
                Tenant = $tenant.displayName
                TenantId = $tenant.Id
                ResourceType = 'Group'
                ResourceName = (Resolve-String -Text $definition.displayName)
                DesiredConfiguration = $definition
            }            
            $resource = (Invoke-MgGraphRequest -Method GET -Uri ("$script:graphBaseUrl/groups/?`$filter=displayName eq '{0}'" -f [System.Web.HttpUtility]::UrlEncode($definition.displayName))).Value

            switch ($resource.Count) {
                0 {
                    if ($definition.present) {                    
                        $result = New-TestResult @result -ActionType "Create"
                    }
                    else {                    
                        $result = New-TestResult @result -ActionType "NoActionRequired"
                    }
                }
                1 {
                    $result["GraphResource"] = $resource
                    if ($definition.present) {
                        $changes = @()
                        foreach ($property in ($definition.Properties() | Where-Object {$_ -notin "displayName", "present", "sourceConfig"})) {
                            $change = [PSCustomObject] @{
                                Property = $property
                                Actions = $null
                            }
                            switch ($property) {
                                "members" {
                                    $resourceMembers = (Invoke-MgGraphRequest -Method GET -Uri ("$script:graphBaseUrl/groups/{0}/members" -f $resource.Id)).Value.Id
                                    $change.Actions = Compare-ResourceList -ReferenceList $resourceMembers `
                                                        -DifferenceList $($definition.members | ForEach-Object {Resolve-User -InputReference $_ -Cmdlet $Cmdlet}) `
                                                        -Cmdlet $PSCmdlet
                                }
                                "owners" {                                    
                                    $resourceOwners = (Invoke-MgGraphRequest -Method GET -Uri ("$script:graphBaseUrl/groups/{0}/owners" -f $resource.Id)).Value.Id
                                    $change.Actions = Compare-ResourceList -ReferenceList $resourceOwners `
                                                        -DifferenceList $($definition.owners | ForEach-Object {Resolve-User -InputReference $_ -Cmdlet $Cmdlet}) `
                                                        -Cmdlet $PSCmdlet
                                }
                                "membershipRule" {
                                    if ($definition.$property -ne $resource.$property) {
                                        $change.Actions = @{"Set" = $definition.$property}
                                        $changes += [PSCustomObject] @{
                                            Property = "membershipRuleProcessingState"                                        
                                            Actions = @{"Set" = "On"}
                                        }
                                    }                                
                                }
                                "groupTypes" {
                                    if ($resource.groupTypes) {
                                        if (Compare-Object -ReferenceObject $resource.groupTypes -DifferenceObject $definition.groupTypes) {
                                            $change.Actions = @{"Set" = $definition.groupTypes}
                                        }
                                    }
                                    else {
                                        if ($definition.groupTypes.count -gt 0) {
                                            $change.Actions = @{"Set" = $definition.groupTypes}
                                        }
                                    }                                    
                                }
                                default {
                                    if ($definition.$property -ne $resource.$property) {
                                        $change.Actions = @{"Set" = $definition.$property}
                                    }
                                }
                            }
                            if ($change.Actions) {$changes += $change}
                        }
    
                        if ($changes.count -gt 0) { $result = New-TestResult @result -Changes $changes -ActionType "Update"}
                        else { $result = New-TestResult @result -ActionType "NoActionRequired" }
                    }
                    else {
                        $result = New-TestResult @result -ActionType "Delete"
                    }
                }
                default {
                    Write-PSFMessage -Level Warning -String 'TMF.Test.MultipleResourcesError' -StringValues $componentName, $definition.displayName -Tag 'failed'
                    $exception = New-Object System.Data.DataException("Query returned multiple results. Cannot decide which resource to test.")
                    $errorID = 'MultipleResourcesError'
                    $category = [System.Management.Automation.ErrorCategory]::NotSpecified
                    $recordObject = New-Object System.Management.Automation.ErrorRecord($exception, $errorID, $category, $Cmdlet)
                    $cmdlet.ThrowTerminatingError($recordObject)
                }
            }
            
            $result
        }
    }
}