Mark as @internal we maybe change the caching mechanic in future.

This looks unexpected we do NOT use here a memoize based cache mechanic here.

We need cache here by id (single) and merge it for next call. We can have first call with [1, 2] second with [1, 3] then the decorated is only called with [3].:

Would try to not mock instead create anonymous class implementation which unset an array and would throw a exception if it calls the same id again:

    public static array $values = []; 

    public function load(array $ids, ?string $locale, array $params = []): array
    {
        $models = [];
        foreach ($ids as $id) {
            if (!isset(self::$values[$id])) {
                 throw new LogicException('The CachedResourceLoader should never call the same "id" multiple times. Id "%s" requested again');
            }
            
            $models = self::$values[$ids];
            unset(self::$values[$ids]); // unset to test not called again with same id
        }
        
        return $models;
    }

You can at start of every test refill it with:

$this->decoratedResourceLoader::$values = [1 => ...]

This way we not require any mocking.

we should not sue a mocked test here we should create a test using AbstractCompilerPassTestCase in this case.

@Prokyonn verify if necessary