3.10. State

3.10.1. Zweck

Kapselt verschiedene Verhaltensweisen für die selbe Routine basierend auf einem Objekt-State. Das kann ein sauberer Weg für ein Objekt sein, sein Verhalten während der Laufzeit ohne komplexe konditionale Bedingungen ändern zu können.

3.10.2. UML-Diagramm

3.10.3. Code

Du findest den Code hierzu auf 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());
    }
}