<?php

Interface ValidationInterface
{
    public function validate();
}

Class Validator
{
    public function createValidation(ValidationInterface $validation)
    {
        return new Validation($validation);
    }
}

Class Validation implements ValidationInterface
{
    private $validation;

    private $messages;

    public function __construct(ValidationInterface $validation)
    {
        $this->validation = $validation;
    }

    public function getMessages()
    {
        return $this->messages;
    }

    public function validate()
    {
        $messages = $this->validation->validate();

        $this->messages = array_merge($this->messages ?? [], $messages);

        return true;
    }
}

Class MyValidation implements ValidationInterface
{
    public function validate()
    {
        return [ 'Hello World' ];
    }
}

$validator = new Validator();
$validation = $validator->createValidation(new MyValidation());
$validation->validate();

var_dump($validation->getMessages());