Decorator Design Pattern

Author: Hyunk3l

Structural/Decorator/ApiResponse.php

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+<?php
+
+namespace PhpDesignPatterns\Structural\Decorator;
+
+/**
+ * Class ApiResponse
+ * @package PhpDesignPatterns\Structural\Decorator
+ */
+class ApiResponse implements ResponseInterface
+{
+    /**
+     * Render the api response.
+     *
+     * @return mixed
+     */
+    public function render()
+    {
+        return array(
+            'status'    => 'ok',
+            'message'   =>  'raw api response',
+        );
+    }
+}

Structural/Decorator/Decorator.php

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+<?php
+
+namespace PhpDesignPatterns\Structural\Decorator;
+
+/**
+ * Abstract class Decorator
+ *
+ * Provides basic methods for Concrete Decorators.
+ *
+ * @package PhpDesignPatterns\Structural\Decorator
+ */
+abstract class Decorator implements ResponseInterface
+{
+    /**
+     * Instance of ResponseInterface.
+     *
+     * @var ResponseInterface
+     */
+    protected $wrapper;
+
+    /**
+     *
+     * @param ResponseInterface $response The object we need to extend responsabilities to.
+     */
+    public function __construct(ResponseInterface $response)
+    {
+        $this->wrapper = $response;
+    }
+}

Structural/Decorator/JsonResponse.php

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+<?php
+
+namespace PhpDesignPatterns\Structural\Decorator;
+
+/**
+ * Class JsonResponse
+ * @package PhpDesignPatterns\Structural\Decorator
+ */
+class JsonResponse extends Decorator
+{
+    /**
+     * Transform output to json.
+     *
+     * @return string
+     */
+    public function render()
+    {
+        $output = $this->wrapper->render();
+        return json_encode($output);
+    }
+}

Structural/Decorator/README.md

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+# Decorator Design Pattern
+
+### Intent
+
+“Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.”
+
+Excerpt From: Erich Gamma. “Design Patterns: Elements of Reusable Object-Oriented Software.” 
+

Structural/Decorator/ResponseInterface.php

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+<?php
+
+namespace PhpDesignPatterns\Structural\Decorator;
+
+/**
+ * Interface ResponseInterface
+ * @package PhpDesignPatterns\Structural\Decorator
+ */
+interface ResponseInterface
+{
+    /**
+     * Return rendered output.
+     *
+     * @return mixed
+     */
+    public function render();
+}

Structural/Decorator/XmlResponse.php

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+<?php
+
+namespace PhpDesignPatterns\Structural\Decorator;
+
+/**
+ * Class XmlResponse
+ * @package PhpDesignPatterns\Structural\Decorator
+ */
+class XmlResponse extends Decorator
+{
+    /**
+     * Transform output to json.
+     *
+     * @return string
+     */
+    public function render()
+    {
+        $output = $this->wrapper->render();
+        $xml    = new \SimpleXMLElement("<root />");
+        foreach($output as $row_key => $row_value) {
+            $xml->addChild($row_key, $row_value);
+        }
+        return $xml->asXml();
+    }
+}

Tests/Structural/Decorator/ApiResponseTest.php

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+<?php
+
+namespace PhpDesignPatterns\Tests\Structural\Decorator;
+
+use PhpDesignPatterns\Structural\Decorator\ApiResponse;
+
+/**
+ * Class ApiResponseTest
+ * @package Tests\Structural\Decorator
+ */
+class ApiResponseTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Instance needed for testing.
+     *
+     * @var ApiResponse
+     */
+    private $api_response;
+
+    /**
+     * Testing render.
+     */
+    public function testRender()
+    {
+        $expected   = array(
+            'status'    => 'ok',
+            'message'   =>  'raw api response',
+        );
+        $this->api_response = new ApiResponse();
+        $this->assertEquals($expected, $this->api_response->render(), 'The result is not the expected one.');
+    }
+}

Tests/Structural/Decorator/JsonResponseTest.php

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+<?php
+
+namespace PhpDesignPatterns\Tests\Structural\Decorator;
+
+use PhpDesignPatterns\Structural\Decorator\JsonResponse;
+
+/**
+ * Class JsonResponseTest
+ * @package PhpDesignPatterns\Tests\Structural\Decorator
+ */
+class JsonResponseTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test instance.
+     *
+     * @var JsonResponse
+     */
+    private $json_render;
+
+    /**
+     * Testing decorated render.
+     */
+    public function testRender()
+    {
+        $fake_render = array('message' => 'api response to json');
+        $api_mock = $this->getMock('PhpDesignPatterns\\Structural\\Decorator\\ResponseInterface', array('render'));
+        $api_mock
+            ->expects($this->once())
+            ->method('render')
+            ->will($this->returnValue($fake_render))
+        ;
+        $this->json_render = new JsonResponse($api_mock);
+        $expected = '{"message":"api response to json"}';
+        $this->assertEquals($expected, $this->json_render->render());
+    }
+}

Tests/Structural/Decorator/XmlResponseTest.php

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+<?php
+
+namespace PhpDesignPatterns\Tests\Structural\Decorator;
+
+use PhpDesignPatterns\Structural\Decorator\XmlResponse;
+
+/**
+ * Class XmlResponseTest
+ * @package PhpDesignPatterns\Tests\Structural\Decorator
+ */
+class XmlResponseTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test instance.
+     *
+     * @var XmlResponse
+     */
+    private $xml_render;
+
+    /**
+     * Testing decorated render.
+     */
+    public function testRender()
+    {
+        $fake_render = array('message' => 'api response to xml');
+        $api_mock = $this->getMock('PhpDesignPatterns\\Structural\\Decorator\\ResponseInterface', array('render'));
+        $api_mock
+            ->expects($this->once())
+            ->method('render')
+            ->will($this->returnValue($fake_render))
+        ;
+        $this->xml_render = new XmlResponse($api_mock);
+        $expected = <<<XML
+<?xml version="1.0"?>
+<root><message>api response to xml</message></root>\n
+XML;
+        $this->assertEquals($expected, $this->xml_render->render());
+    }
+}