// Closure to be spied on
$fn = function ($a, $b) {
    return $a + $b;
};

// Replace closure with a spy
$fn = new \Callable\Spy($fn);

echo $fn(5, 3); // Output: 8 (through spy proxy)

// Gets last call made through spy proxy
$lastCall = $fn->getLastCall();

$timestamp = $lastCall->getDate();          // Timestamp of call
$stackTrace = $lastCall->getStackTrace();   // Full stack-trace of call

print_r($lastCall->getArgs());      // Output: [5, 3]
print_r($lastCall->getResult());    // Output: 8

更多示例，请查看上方的 examples 文件夹！此外，测试文件夹中还有更多作为测试的示例。