Follow the chain without redefining completeness

Prepare the lab

Use PowerShell 7. This script simulates two Graph-shaped pages. It deliberately does not import the Graph module or call Microsoft services.

$ErrorActionPreference = 'Stop'
$pages = @{
    'page-1' = @{value=@([pscustomobject]@{id='1';displayName='Ana'});'@odata.nextLink'='page-2'}
    'page-2' = @{value=@([pscustomobject]@{id='2';displayName='Ben'});'@odata.nextLink'=$null}
}
function Read-FixturePages {
    param([hashtable]$Pages,[string]$First)
    $seen = [System.Collections.Generic.HashSet[string]]::new()
    $url = $First
    $items = [System.Collections.Generic.List[object]]::new()
    while ($url) {
        if (-not $seen.Add($url)) { throw 'Repeated page link' }
        if (-not $Pages.ContainsKey($url)) { throw 'Missing page response' }
        $page = $Pages[$url]
        foreach ($item in $page.value) { $items.Add($item) }
        $url = $page['@odata.nextLink']
    }
    return $items.ToArray()
}
$result = @(Read-FixturePages -Pages $pages -First 'page-1')
$result | Select-Object id,displayName | Format-Table
if (($result.id -join ',') -ne '1,2') { throw 'Pagination test failed' }

Work through the evidence

Draw the page chain

Write page-1 → page-2 → end before execution. Count records separately from pages: two pages could contain zero, two, or hundreds of records. A page count is not a user count.

Test an empty complete result

Set page-1 value to an empty array and its next-link to null. The function should return no items without claiming that collection failed. Then remove page-1 from the fixture and verify that missing response fails explicitly.

Inject a loop

Set page-2 next-link to page-1. The function must throw Repeated page link. Explain why silently treating a repeated URL as end-of-data could conceal a broken provider or collector.