test_empty.php

<?php

require_once __DIR__.'/vendor/autoload.php';

use Box\Spout\Writer\WriterFactory;
use Box\Spout\Reader\ReaderFactory;

$testData = [
    ['Hi', 'There', ''],
    [null, null, null],
    ['', 'Hi', 'There'],
    ['', '', ''],
];

function readAndDump($writerType, $testData) {

    $writer = WriterFactory::create($writerType);
    $writer->openToFile(__DIR__ . '/writer_'.$writerType.'.'.$writerType);
    $writer->addRows($testData);
    $writer->close();

    $result = readTestFile(__DIR__ . '/writer_'.$writerType.'.'.$writerType, $writerType);
    print $writerType.PHP_EOL;
    print_r($result);
}

function readTestFile($fileName, $readerType)
{
    $result = [];
    /** @var \Box\Spout\Reader\XLSX\Reader $reader */
    $reader = ReaderFactory::create($readerType);
    $reader->setShouldPreserveEmptyRows(false);
    $reader->open($fileName);

    foreach ($reader->getSheetIterator() as $sheet) {
        foreach ($sheet->getRowIterator() as $row) {
            $result[] = $row;
        }
    }
    $reader->close();
    return $result;
}

readAndDump('ods', $testData);
readAndDump('csv', $testData);
readAndDump('xlsx', $testData);

/**
frosch ➜ spout-bug-finder php test.php
ods
Array
(
    [0] => Array
        (
            [0] => Hi
            [1] => There
            [2] => 
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => 
        )

    [2] => Array
        (
            [0] => 
            [1] => Hi
            [2] => There
        )

)
csv
Array
(
    [0] => Array
        (
            [0] => Hi
            [1] => There
            [2] => 
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => 
        )

    [2] => Array
        (
            [0] => 
            [1] => Hi
            [2] => There
        )

    [3] => Array
        (
            [0] => 
            [1] => 
            [2] => 
        )

)
xlsx
Array
(
    [0] => Array
        (
            [0] => Hi
            [1] => There
            [2] => 
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => 
        )

    [2] => Array
        (
            [0] => 
            [1] => Hi
            [2] => There
        )

    [3] => Array
        (
            [0] => 
            [1] => 
            [2] => 
        )

)

*/