Major release of Yii Aliases package was tagged.
In this version configuration group names adapted to Yii conventions and added method Aliases::getArray() that bulk translates path aliases into actual paths. For example:
$aliases = new Aliases([
'@root' => '/my/app',
]);

// Value will be ['src' => '/my/app/src', 'tests' => '/my/app/tests']
$directories = $aliases->getArray(['src' => '@root/src', 'tests' => '@root/tests']);