first shot an row RowManager and make CSV tests pass

src/Spout/Writer/Common/Creator/EntityFactory.php

@@ -2,7 +2,9 @@
 
 namespace Box\Spout\Writer\Common\Creator;
 
+use Box\Spout\Writer\Common\Entity\Row;
 use Box\Spout\Writer\Common\Entity\Sheet;
+use Box\Spout\Writer\Common\Entity\Style\Style;
 use Box\Spout\Writer\Common\Entity\Workbook;
 use Box\Spout\Writer\Common\Entity\Worksheet;
 
@@ -55,4 +57,15 @@ class EntityFactory
         $sheetManager = $this->managerFactory->createSheetManager();
         return new Sheet($sheetIndex, $associatedWorkbookId, $sheetManager);
     }
+
+    /**
+     * @param array $cells
+     * @param Style|null $style
+     * @return Row
+     */
+    public function createRow(array $cells, Style $style = null)
+    {
+        $rowManager = $this->managerFactory->createRowManager();
+        return new Row($cells, $style, $rowManager);
+    }
 }

src/Spout/Writer/Common/Creator/ManagerFactory.php

@@ -3,7 +3,10 @@
 namespace Box\Spout\Writer\Common\Creator;
 
 use Box\Spout\Common\Helper\StringHelper;
+use Box\Spout\Writer\Common\Manager\CellManager;
+use Box\Spout\Writer\Common\Manager\RowManager;
 use Box\Spout\Writer\Common\Manager\SheetManager;
+use Box\Spout\Writer\Common\Manager\Style\StyleMerger;
 
 /**
  * Class ManagerFactory
@@ -13,6 +16,24 @@ use Box\Spout\Writer\Common\Manager\SheetManager;
  */
 class ManagerFactory
 {
+    /**
+     * @return CellManager
+     */
+    public function createCellManager()
+    {
+        $styleMerger = new StyleMerger();
+        return new CellManager($styleMerger);
+    }
+
+    /**
+     * @return RowManager
+     */
+    public function createRowManager()
+    {
+        $styleMerger = new StyleMerger();
+        return new RowManager($styleMerger);
+    }
+
     /**
      * @return SheetManager
      */

src/Spout/Writer/Common/Entity/Row.php

@@ -3,6 +3,7 @@
 namespace Box\Spout\Writer\Common\Entity;
 
 use Box\Spout\Writer\Common\Entity\Style\Style;
+use Box\Spout\Writer\Common\Manager\RowManager;
 use Box\Spout\Writer\Common\Manager\Style\StyleMerger;
 
 class Row
@@ -20,22 +21,24 @@ class Row
     protected $style = null;
 
     /**
-     * @var StyleMerger
+     * Thw row manager
+     * @var RowManager
      */
-    protected $styleMerger;
+    protected $rowManager;
 
     /**
      * Row constructor.
      * @param Cell[] $cells
      * @param Style|null $style
+     * @param RowManager $rowManager
      */
-    public function __construct(array $cells = [], Style $style = null)
+    public function __construct(array $cells = [], Style $style = null, RowManager $rowManager)
     {
         $this
             ->setCells($cells)
             ->setStyle($style);
 
-        $this->styleMerger = new StyleMerger();
+        $this->rowManager = $rowManager;
     }
 
     /**
@@ -86,11 +89,7 @@ class Row
      */
     public function applyStyle(Style $style = null)
     {
-        if ($style === null) {
+        $this->rowManager->applyStyle($this, $style);
-            return $this;
-        }
-        $merged = $this->styleMerger->merge($this->getStyle(), $style);
-        $this->setStyle($merged);
         return $this;
     }
 
@@ -112,6 +111,6 @@ class Row
      */
     public function isEmpty()
     {
-        return count($this->cells) === 0 || (count($this->cells) === 1 && $this->cells[0]->isEmpty());
+        return $this->rowManager->isEmpty($this);
     }
 }

src/Spout/Writer/Common/Manager/RowManager.php

@@ -31,4 +31,17 @@ class RowManager
         $mergedStyle = $this->styleMerger->merge($row->getStyle(), $style);
         $row->setStyle($mergedStyle);
     }
+
+    /**
+     * Detect whether a row is considered empty.
+     * An empty row has either no cells at all - or only one empty cell
+     *
+     * @param Row $row
+     * @return bool
+     */
+    public function isEmpty(Row $row)
+    {
+        $cells = $row->getCells();
+        return count($cells) === 0 || (count($cells) === 1 && $cells[0]->isEmpty());
+    }
 }

src/Spout/Writer/WriterAbstract.php

@@ -54,7 +54,8 @@ abstract class WriterAbstract implements WriterInterface
         OptionsManagerInterface $optionsManager,
         StyleMerger $styleMerger,
         GlobalFunctionsHelper $globalFunctionsHelper
-    ) {
+    )
+    {
         $this->optionsManager = $optionsManager;
         $this->styleMerger = $styleMerger;
         $this->globalFunctionsHelper = $globalFunctionsHelper;

tests/Spout/Writer/CSV/WriterTest.php

@@ -5,6 +5,8 @@ namespace Box\Spout\Writer\CSV;
 use Box\Spout\TestUsingResource;
 use Box\Spout\Common\Type;
 use Box\Spout\Common\Helper\EncodingHelper;
+use Box\Spout\Writer\Common\Creator\EntityFactory;
+use Box\Spout\Writer\Common\Creator\ManagerFactory;
 use Box\Spout\Writer\Common\Entity\Cell;
 use Box\Spout\Writer\WriterFactory;
 
@@ -17,6 +19,17 @@ class WriterTest extends \PHPUnit_Framework_TestCase
 {
     use TestUsingResource;
 
+    /**
+     * @var EntityFactory
+     */
+    protected $entityFactory;
+
+    protected function setUp()
+    {
+        $this->entityFactory = new EntityFactory(new ManagerFactory());
+        parent::setUp();
+    }
+
     /**
      * @expectedException \Box\Spout\Common\Exception\IOException
      */
@@ -28,7 +41,11 @@ class WriterTest extends \PHPUnit_Framework_TestCase
 
         $writer = WriterFactory::create(Type::CSV);
         @$writer->openToFile($filePath);
-        $writer->addRow(['csv--11', 'csv--12']);
+        $row = $this->entityFactory->createRow([
+            new Cell('csv--11'),
+            new Cell('csv--12')
+        ]);
+        $writer->addRow($row);
         $writer->close();
     }
 
@@ -38,7 +55,11 @@ class WriterTest extends \PHPUnit_Framework_TestCase
     public function testWriteShouldThrowExceptionIfCallAddRowBeforeOpeningWriter()
     {
         $writer = WriterFactory::create(Type::CSV);
-        $writer->addRow(['csv--11', 'csv--12']);
+        $row = $this->entityFactory->createRow([
+            new Cell('csv--11'),
+            new Cell('csv--12')
+        ]);
+        $writer->addRow($row);
         $writer->close();
     }
 
@@ -48,17 +69,24 @@ class WriterTest extends \PHPUnit_Framework_TestCase
     public function testWriteShouldThrowExceptionIfCallAddRowsBeforeOpeningWriter()
     {
         $writer = WriterFactory::create(Type::CSV);
-        $writer->addRows([['csv--11', 'csv--12']]);
+        $row = $this->entityFactory->createRow([
+            new Cell('csv--11'),
+            new Cell('csv--12')
+        ]);
+        $writer->addRows([$row]);
         $writer->close();
     }
 
-    /**
+    public function testAddRowsShouldThrowExceptionIfRowsAreNotArrayOfRows()
-     * @expectedException \Box\Spout\Common\Exception\InvalidArgumentException
-     */
-    public function testAddRowsShouldThrowExceptionIfRowsAreNotArrayOfArrays()
     {
+        if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
+            $this->expectException(\TypeError::class);
+        } else {
+            $this->markTestSkipped('PHP > 7.0 only');
+        }
         $writer = WriterFactory::create(Type::CSV);
-        $writer->addRows(['csv--11', 'csv--12']);
+        $row = new \stdClass();
+        $writer->addRows([$row]);
         $writer->close();
     }
 
@@ -192,11 +220,11 @@ class WriterTest extends \PHPUnit_Framework_TestCase
     }
 
     /**
-     * @param array  $allRows
+     * @param array $allRows
      * @param string $fileName
      * @param string $fieldDelimiter
      * @param string $fieldEnclosure
-     * @param bool   $shouldAddBOM
+     * @param bool $shouldAddBOM
      * @return null|string
      */
     private function writeToCsvFileAndReturnWrittenContent($allRows, $fileName, $fieldDelimiter = ',', $fieldEnclosure = '"', $shouldAddBOM = true)
@@ -211,7 +239,13 @@ class WriterTest extends \PHPUnit_Framework_TestCase
         $writer->setShouldAddBOM($shouldAddBOM);
 
         $writer->openToFile($resourcePath);
-        $writer->addRows($allRows);
+
+        $writer->addRows(array_map(function ($oneRow) {
+            $row = $this->entityFactory->createRow(array_map(function ($value) {
+                return new Cell($value);
+            }, $oneRow));
+            return $row;
+        }, $allRows));
         $writer->close();
 
         return file_get_contents($resourcePath);