public function namespaceWithUnderscoresAreLoaded()
{
mkdir('vfs://Test/Packages/Application/Acme.MyApp/Classes/Acme/MyApp/My_Underscore', 0770, true);
file_put_contents('vfs://Test/Packages/Application/Acme.MyApp/Classes/Acme/MyApp/My_Underscore/Foo.php', '<?php ' . __CLASS__ . '::$testClassWasLoaded = TRUE; ?>');
$this->classLoader->loadClass('Acme\\MyApp\\My_Underscore\\Foo');
$this->assertTrue(self::$testClassWasLoaded);
}