Skipped cells are in wrong order

This only happens when no sheet's dimension is specified.
When filling empty cells with empty strings, we push these new cells with the correct cell index but they are added at the end of the cells array (normal PHP behavior). This means that we were going from `{[0] => 'A', [2] => 'C'}` to `{[0] => 'A', [2] => 'C', [1] => ''}`. We therefore need to sort the array to get the values in the correct order ( `{[0] => 'A', [1] => '', [2] => 'C'}`).

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

@@ -56,12 +56,25 @@ class RowManager
         $rowCells = $row->getCells();
         $maxCellIndex = $numCells;
 
+        // If the row has empty cells, calling "setCellAtIndex" will add the cell
+        // but in the wrong place (the new cell is added at the end of the array).
+        // Therefore, we need to sort the array using keys to have proper order.
+        // @see https://github.com/box/spout/issues/740
+        $needsSorting = false;
+
         for ($cellIndex = 0; $cellIndex < $maxCellIndex; $cellIndex++) {
             if (!isset($rowCells[$cellIndex])) {
                 $row->setCellAtIndex($this->entityFactory->createCell(''), $cellIndex);
+                $needsSorting = true;
             }
         }
 
+        if ($needsSorting) {
+            $rowCells = $row->getCells();
+            ksort($rowCells);
+            $row->setCells($rowCells);
+        }
+
         return $row;
     }
 }

tests/Spout/Reader/XLSX/ReaderTest.php

@@ -692,13 +692,29 @@ class ReaderTest extends TestCase
         $allRows = $this->getAllRowsForFile('sheet_with_empty_cells.xlsx');
 
         $expectedRows = [
-            ['A', 'B', 'C'],
+            ['A', '', 'C'],
             ['0', '', ''],
             ['1', '1', ''],
         ];
         $this->assertEquals($expectedRows, $allRows, 'There should be 3 rows, with equal length');
     }
 
+    /**
+     * https://github.com/box/spout/issues/184
+     * @return void
+     */
+    public function testReadShouldCreateOutputEmptyCellPreservedWhenNoDimensionsSpecified()
+    {
+        $allRows = $this->getAllRowsForFile('sheet_with_empty_cells_without_dimensions.xlsx');
+
+        $expectedRows = [
+            ['A', '', 'C'],
+            ['0'],
+            ['1', '1'],
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * https://github.com/box/spout/issues/195
      * @return void