Method of subclass is not detected when parent class contains a deprecated method

[achasseux]

Exemple with symfony 3.4 :

• AppKernel is a subclass of Symfony\Component\HttpKernel\Kernel with a deprecated loadClassCache() method since symfony 3.3, but AppKernel is not detected
• web/app_dev.php calls the deprecated method for AppKernel

$kernel = new AppKernel('dev', true);
$kernel->loadClassCache();

When you run
./vendor/bin/deprecation-detector check web/ vendor/
No violation detected.

I have noticed an issue in your RuleSet into "hasMethod()" or "getMethod()" methods :

    public function hasMethod($method, $class)
    {
        return isset($this->methodDeprecations[$class][$method]);
    }

If $class is a subclass of the deprecated class, the method is not detected.

The next method could detect this type of deprecated method :

    public function getMethod($method, $class)
    {
        foreach ($this->methodDeprecations as $className => $methodDeprecation) {
            if (isset($methodDeprecation[$method]) && ($class === $className || is_subclass_of($class, $className))) {
                return $methodDeprecation[$method];
            }
        }

        return;
    }

The is_subclass_of() function could not work if the autoloads of the project are not included.
For example, the vendor/autoload.php of my symfony project file has to be loaded in order to call the is_subclass_of() function.