Set wrap text style when multiline string encountered

Fixes #10
If a cell contains a multiline string, "wrap text" style option should
automatically be set.

tests/Spout/Writer/XLSX/Helper/StyleHelperTest.php

@@ -56,4 +56,34 @@ class StyleHelperTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(1, $registeredStyle1->getId());
         $this->assertEquals(1, $registeredStyle2->getId());
     }
+
+    /**
+     * @return void
+     */
+    public function testApplyExtraStylesIfNeededShouldApplyWrapTextIfCellContainsNewLine()
+    {
+        $style = clone $this->defaultStyle;
+        $styleHelper = new StyleHelper($this->defaultStyle);
+
+        $this->assertFalse($style->shouldWrapText());
+
+        $updatedStyle = $styleHelper->applyExtraStylesIfNeeded($style, [12, 'single line', "multi\nlines", null]);
+
+        $this->assertTrue($updatedStyle->shouldWrapText());
+    }
+
+    /**
+     * @return void
+     */
+    public function testApplyExtraStylesIfNeededShouldDoNothingIfWrapTextAlreadyApplied()
+    {
+        $style = (new StyleBuilder())->setShouldWrapText()->build();
+        $styleHelper = new StyleHelper($this->defaultStyle);
+
+        $this->assertTrue($style->shouldWrapText());
+
+        $updatedStyle = $styleHelper->applyExtraStylesIfNeeded($style, ["multi\nlines"]);
+
+        $this->assertTrue($updatedStyle->shouldWrapText());
+    }
 }

tests/Spout/Writer/XLSX/WriterWithStyleTest.php

@@ -206,6 +206,25 @@ class WriterWithStyleTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals('1', $cellDomElements[1]->getAttribute('s'));
     }
 
+    /**
+     * @return void
+     */
+    public function testAddRowWithStyleShouldApplyWrapTextIfCellContainsNewLine()
+    {
+        $fileName = 'test_add_row_with_style_should_apply_wrap_text_if_new_lines.xlsx';
+        $dataRows = [
+            ["xlsx--11\nxlsx--11"],
+            ['xlsx--21'],
+        ];
+
+        $this->writeToXLSXFile($dataRows, $fileName, $this->defaultStyle);
+
+        $cellXfsDomElement = $this->getXmlSectionFromStylesXmlFile($fileName, 'cellXfs');
+        $xfElement = $cellXfsDomElement->getElementsByTagName('xf')->item(1);
+        $this->assertEquals(1, $xfElement->getAttribute('applyAlignment'));
+        $this->assertFirstChildHasAttributeEquals('1', $xfElement, 'alignment', 'wrapText');
+    }
+
     /**
      * @param array $allRows
      * @param string $fileName