Refactory Writer Styles to match new code organization (#433)

Decomposed old StyleHelper into StyleManager, StyleRegistry and StyleMerger.

tests/Spout/Writer/Common/Manager/Style/StyleRegistryTest.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace Box\Spout\Writer\Common\Manager\Style;
+
+use Box\Spout\Writer\Common\Creator\Style\BorderBuilder;
+use Box\Spout\Writer\Common\Creator\Style\StyleBuilder;
+use Box\Spout\Writer\Common\Entity\Style\Border;
+use Box\Spout\Writer\Common\Entity\Style\Color;
+use Box\Spout\Writer\Common\Entity\Style\Style;
+
+/**
+ * Class StyleRegistryTest
+ *
+ * @package Box\Spout\Writer\Common\Manager\Style
+ */
+class StyleRegistryTest extends \PHPUnit_Framework_TestCase
+{
+    /** @var Style */
+    private $defaultStyle;
+
+    /** @var StyleRegistry */
+    private $styleRegistry;
+
+    /**
+     * @return void
+     */
+    public function setUp()
+    {
+        $this->defaultStyle = (new StyleBuilder())->build();
+        $this->styleRegistry = new StyleRegistry($this->defaultStyle);
+    }
+
+    /**
+     * @return void
+     */
+    public function testSerializeShouldNotTakeIntoAccountId()
+    {
+        $style1 = (new StyleBuilder())->setFontBold()->build();
+        $style1->setId(1);
+
+        $style2 = (new StyleBuilder())->setFontBold()->build();
+        $style2->setId(2);
+
+        $this->assertEquals($this->styleRegistry->serialize($style1), $this->styleRegistry->serialize($style2));
+    }
+
+    /**
+     * @return void
+     */
+    public function testRegisterStyleShouldUpdateId()
+    {
+        $style1 = (new StyleBuilder())->setFontBold()->build();
+        $style2 = (new StyleBuilder())->setFontUnderline()->build();
+
+        $this->assertEquals(0, $this->defaultStyle->getId(), 'Default style ID should be 0');
+        $this->assertNull($style1->getId());
+        $this->assertNull($style2->getId());
+
+        $registeredStyle1 = $this->styleRegistry->registerStyle($style1);
+        $registeredStyle2 = $this->styleRegistry->registerStyle($style2);
+
+        $this->assertEquals(1, $registeredStyle1->getId());
+        $this->assertEquals(2, $registeredStyle2->getId());
+    }
+
+    /**
+     * @return void
+     */
+    public function testRegisterStyleShouldReuseAlreadyRegisteredStyles()
+    {
+        $style = (new StyleBuilder())->setFontBold()->build();
+
+        $registeredStyle1 = $this->styleRegistry->registerStyle($style);
+        $registeredStyle2 = $this->styleRegistry->registerStyle($style);
+
+        $this->assertEquals(1, $registeredStyle1->getId());
+        $this->assertEquals(1, $registeredStyle2->getId());
+    }
+}