Validation can succeed only on first attempt

[plai2010]

Validation succeeds only if the correct answer is given to the first check() or check_api() call. If a user enters an incorrect value, they cannot try again; instead a new captcha must be generated. I think that is because we use Cache::pull() rather than Cache::get() in the check code:

if (!Cache::pull($this->get_cache_key($key))) {
    return false;
}

The problem can be illustrated with artisan tinker running this:

$testCaptcha = function(bool $positive) {
	echo ">>> Testing Captcha ...\n";
	$captcha = app('captcha');

	$challenge = (object)$captcha->create(api:true);
	$key = $challenge->key;
	echo "Challenge Key: {$key}\n";

	$ans = implode('', Cache::get('captcha_'.md5($key)));
	echo "Answer: $ans\n";

	$attempts = $positive ? [ $ans ] : [
		"bad-{$ans}",
		$ans,
	];

	foreach ($attempts as $try) {
		$label = $try == $ans ? 'correct' : 'incorrect';
		echo "Attempting {$label} '{$try}' ... ";
		$res = $captcha->check_api($try, $key);
		echo json_encode($res), "\n";
	}
};

$testCaptcha(true);
$testCaptcha(false);

Example output follows:

Psy Shell v0.12.4 (PHP 8.3.13 — cli) by Justin Hileman
>>> Testing Captcha ...
Challenge Key: $2y$12$p7oNGQVf9zp3UxVjfImhz.Hf2RKvEcRuI6/FdWeX2JBuHjMBH89eu
Answer: 410204101
Attempting correct '410204101' ... true
>>> Testing Captcha ...
Challenge Key: $2y$12$luzJOGY3ULHhHx9ZP.W8BeGH.BwXylczwZO8XthleQFwoI2GKrumy
Answer: 906279280
Attempting incorrect 'bad-906279280' ... false
Attempting correct '906279280' ... false