Test-AccessToken fails for non-English locales (e.g. German) due to InvariantCulture date parsing

[Triphos77]

Module version: 1.5.0

OS/PowerShell version: Windows, PowerShell 5.1/7.x with German locale (de-DE)

Description:
Test-AccessToken always returns $false on systems with a non-English Windows locale, causing every Graph API call to attempt a silent token refresh, which then fails with:

"Cannot validate argument on parameter 'ClientID'. The argument is null or empty."

Root cause:
In Test-AccessToken.ps1, the ExpiresOn property is converted to a string using the
system's local culture (e.g. "03.04.2026" in de-DE = DD.MM.YYYY), but then parsed
back using InvariantCulture which expects MM.DD.YYYY — interpreting April 3rd as
March 4th, putting the expiry ~30 days in the past.

Problematic line:
$ExpiresOnUTC = [DateTimeOffset]::Parse(
$Global:AccessToken.ExpiresOn.ToString(),
[System.Globalization.CultureInfo]::InvariantCulture,
[System.Globalization.DateTimeStyles]::AssumeUniversal
).ToUniversalTime()

Suggested Fix (with a little help of AI, but this worked for me! Couldnt get it to work otherwise):
Use expires_in (seconds) from the token object to calculate expiry instead of
re-parsing the ExpiresOn string:

if ($Global:AccessToken.PSObject.Properties["expires_in"] -and $Global:AccessToken.expires_in) {
$ExpiresOnUTC = [DateTimeOffset]::UtcNow.AddSeconds($Global:AccessToken.expires_in)
} else {
$ExpiresOnUTC = [DateTimeOffset]::Parse($Global:AccessToken.ExpiresOn.ToString(),
[System.Globalization.CultureInfo]::CurrentCulture,
[System.Globalization.DateTimeStyles]::AssumeLocal).ToUniversalTime()
}

[ASDF-PS]

#210

[FerryBo]

You can add something like this in your script:

$OriginalCulture = [cultureinfo]::CurrentCulture

try {
    [cultureinfo]::CurrentCulture = 'en-US'
    # Do something here, like:
    $Win32App = Add-IntuneWin32App @Win32AppArgs -AllowAvailableUninstall
}
catch {
    Write-Error "Upload failed: $_"
}

# When done, put it back to the original culture:
[cultureinfo]::CurrentCulture = $OriginalCulture