Port Java to PHP with Hamcrest.

php/src/PromotionService/PromotionService.php

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+<?php
+namespace PromotionService;
+
+class Item
+{
+    public $name;
+    public $price;
+    public $tax;
+
+    public function __construct($name, $price, $tax)
+    {
+        $this->name = $name;
+        $this->price = $price;
+        $this->tax = $tax;
+    }
+}
+
+class PromotionService
+{
+
+    public function applyPromotionTo(Item $item)
+    {
+        $result = [];
+        $result[] = new UserMessage(sprintf("Total before promotion: %.1F", $item->price + $item->price * $item->tax));
+
+        $item->price -= $this->standardDiscount();
+        if ($item->price > 122) {
+            $item->tax /= 2;
+        }
+
+        $this->persist($item);
+
+        $result[] = new UserMessage(sprintf("Total after promotion: %.1F", $item->price + $item->price * $item->tax));
+        return $result;
+    }
+
+    // This method can't be moved to another class, used by other code in this class.
+    private function standardDiscount()
+    {
+        return 2;
+    }
+
+    private function persist(Item $item)
+    {
+        // Item is persisted to storage.
+    }
+
+    // ... There is more code in this class.
+}

php/src/PromotionService/UserMessage.php

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+<?php
+namespace PromotionService;
+
+class UserMessage
+{
+
+    private $value;
+
+    public function __construct($value)
+    {
+        $this->value = $value;
+    }
+
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    public function __toString()
+    {
+        return $this->value;
+    }
+
+}

php/test/PromotionService/PromotionServiceTest.php

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+<?php
+namespace PromotionService;
+
+class PromotionServiceTest extends \PHPUnit_Framework_TestCase
+{
+
+    /** @test */
+    public function bookPromotion()
+    {
+        $promotionService = new PromotionService();
+        $messages = $promotionService->applyPromotionTo(
+            new Item("Functional programming with C++", 10, 0.2));
+
+        assertThat($messages, equalTo([
+            new UserMessage("Total before promotion: 12.0"),
+            new UserMessage("Total after promotion: 9.6"),
+        ]));
+    }
+
+    /** @test */
+    public function expensiveBookPromotion()
+    {
+        $promotionService = new PromotionService();
+        $messages = $promotionService->applyPromotionTo(
+            new Item("Functional programming with all languages", 210, 0.2));
+
+        assertThat($messages, equalTo([
+            new UserMessage("Total before promotion: 252.0"),
+            new UserMessage("Total after promotion: 228.8"),
+        ]));
+    }
+
+}