3.10. State

3.10.1. Rôle

Encapsule des comportements différents pour la même routine en fonction de l’état de l’objet. Cela peut être un moyen plus propre pour un objet de changer son comportement au moment de l’exécution sans avoir recours à de grandes déclarations conditionnelles monolithiques.

3.10.2. Diagramme UML

3.10.3. Code

Vous pouvez également trouver ce code sur GitHub

OrderContext.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class OrderContext
{
    private State $state;

    public static function create(): OrderContext
    {
        $order = new self();
        $order->state = new StateCreated();

        return $order;
    }

    public function setState(State $state)
    {
        $this->state = $state;
    }

    public function proceedToNext()
    {
        $this->state->proceedToNext($this);
    }

    public function toString()
    {
        return $this->state->toString();
    }
}

State.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

interface State
{
    public function proceedToNext(OrderContext $context);

    public function toString(): string;
}

StateCreated.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class StateCreated implements State
{
    public function proceedToNext(OrderContext $context)
    {
        $context->setState(new StateShipped());
    }

    public function toString(): string
    {
        return 'created';
    }
}

StateShipped.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class StateShipped implements State
{
    public function proceedToNext(OrderContext $context)
    {
        $context->setState(new StateDone());
    }

    public function toString(): string
    {
        return 'shipped';
    }
}

StateDone.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class StateDone implements State
{
    public function proceedToNext(OrderContext $context)
    {
        // there is nothing more to do
    }

    public function toString(): string
    {
        return 'done';
    }
}

3.10.4. Test

Tests/StateTest.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State\Tests;

use DesignPatterns\Behavioral\State\OrderContext;
use PHPUnit\Framework\TestCase;

class StateTest extends TestCase
{
    public function testIsCreatedWithStateCreated()
    {
        $orderContext = OrderContext::create();

        $this->assertSame('created', $orderContext->toString());
    }

    public function testCanProceedToStateShipped()
    {
        $contextOrder = OrderContext::create();
        $contextOrder->proceedToNext();

        $this->assertSame('shipped', $contextOrder->toString());
    }

    public function testCanProceedToStateDone()
    {
        $contextOrder = OrderContext::create();
        $contextOrder->proceedToNext();
        $contextOrder->proceedToNext();

        $this->assertSame('done', $contextOrder->toString());
    }

    public function testStateDoneIsTheLastPossibleState()
    {
        $contextOrder = OrderContext::create();
        $contextOrder->proceedToNext();
        $contextOrder->proceedToNext();
        $contextOrder->proceedToNext();

        $this->assertSame('done', $contextOrder->toString());
    }
}