3.10. State

3.10.1. Doel

Kapselt wisselend gedrag in voor dezelfde routine op basis van de toestand van een object. Dit kan een schonere manier zijn voor een object om zijn gedrag tijdens runtime te veranderen zonder zijn toevlucht te nemen tot grote monolithische voorwaardelijke uitspraken.

3.10.2. UML Diagram

3.10.3. Code

Je kan deze broncode terugvinden op GitHub

ContextOrder.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class ContextOrder
{
    private StateOrder $state;

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

        return $order;
    }

    public function setState(StateOrder $state): void
    {
        $this->state = $state;
    }

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

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

StateOrder.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

interface StateOrder
{
    public function proceedToNext(ContextOrder $context): void;

    public function toString(): string;
}

CreateOrder.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class CreateOrder implements StateOrder
{
    public function proceedToNext(ContextOrder $context): void
    {
        $context->setState(new ShippingOrder());
    }

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

ShippingOrder.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class ShippingOrder implements StateOrder
{
    public function proceedToNext(ContextOrder $context): void
    {
        $context->setState(new OrderDone());
    }

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

OrderDone.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Behavioral\State;

class OrderDone implements StateOrder
{
    public function proceedToNext(ContextOrder $context): void
    {
        // 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\ContextOrder;
use PHPUnit\Framework\TestCase;

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

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

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

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

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

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

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

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