2.11. Registry

2.11.1. Propósito

Implementar un almacenamiento central para los objetos que se utilizan con frecuencia en toda la aplicación, normalmente se implementa utilizando una clase abstracta con solo métodos estáticos (o usando el patrón Singleton). ¡Recuerde que esto introduce un estado global, que debe ser evitado en todo momento. En su lugar, impleméntelo utilizando la Inyección de Dependencia!

2.11.2. Diagrama UML

2.11.3. Código

Puedes encontrar el código en GitHub

Registry.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Structural\Registry;

use InvalidArgumentException;

abstract class Registry
{
    public const LOGGER = 'logger';

    /**
     * this introduces global state in your application which can not be mocked up for testing
     * and is therefor considered an anti-pattern! Use dependency injection instead!
     *
     * @var Service[]
     */
    private static array $services = [];

    private static array $allowedKeys = [
        self::LOGGER,
    ];

    final public static function set(string $key, Service $value)
    {
        if (!in_array($key, self::$allowedKeys)) {
            throw new InvalidArgumentException('Invalid key given');
        }

        self::$services[$key] = $value;
    }

    final public static function get(string $key): Service
    {
        if (!in_array($key, self::$allowedKeys) || !isset(self::$services[$key])) {
            throw new InvalidArgumentException('Invalid key given');
        }

        return self::$services[$key];
    }
}

Service.php

<?php

namespace DesignPatterns\Structural\Registry;

class Service
{
}

2.11.4. Test

Tests/RegistryTest.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Structural\Registry\Tests;

use InvalidArgumentException;
use DesignPatterns\Structural\Registry\Registry;
use DesignPatterns\Structural\Registry\Service;
use PHPUnit\Framework\TestCase;

class RegistryTest extends TestCase
{
    private Service $service;

    protected function setUp(): void
    {
        $this->service = $this->getMockBuilder(Service::class)->getMock();
    }

    public function testSetAndGetLogger()
    {
        Registry::set(Registry::LOGGER, $this->service);

        $this->assertSame($this->service, Registry::get(Registry::LOGGER));
    }

    public function testThrowsExceptionWhenTryingToSetInvalidKey()
    {
        $this->expectException(InvalidArgumentException::class);

        Registry::set('foobar', $this->service);
    }

    /**
     * notice @runInSeparateProcess here: without it, a previous test might have set it already and
     * testing would not be possible. That's why you should implement Dependency Injection where an
     * injected class may easily be replaced by a mockup
     *
     * @runInSeparateProcess
     */
    public function testThrowsExceptionWhenTryingToGetNotSetKey()
    {
        $this->expectException(InvalidArgumentException::class);

        Registry::get(Registry::LOGGER);
    }
}