src/Constraints/OnlySubsetsInList.php
protected function expected(array $actual): bool
    {
        return collect($this->expected)->contains(function ($expected) use ($actual) {
            return $this->compare($expected, $actual);
        });
    }
protected function expected(array $actual): bool
    {
        return collect($this->expected)->contains(function ($expected) use ($actual) {
            return $this->compare($expected, $actual);
        });
    }
Is the actual subset expected?

@param array $actual
@return bool