Corrections for Xlsx Read Comments (#2329)

This change was suggested by issue #2316. There was a problem reading Xlsx comments which appeared with release 18.0 but which was already fixed in master. So no source change was needed to fix the issue, but I thought we should at least add the test case to our unit tests.

In developing that case, I discovered that, although comment text was read correctly, there was a problem with comment author. In fact, there were two problems. One was new, with the namespacing changes - as in several other cases, the namespaced attribute `authorId` needed some special handling. However, another problem was much older - the code was checking `!empty($comment['authorId'])`, eliminating consideration of authorId=0, and should instead have been checking `isset`. Both problems are now fixed, and tested.

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -957,9 +957,10 @@ public function load(string $pFilename, int $flags = 0): Spreadsheet
                                     // Loop through contents
                                     $contentPath = self::xpathNoFalse($commentsFile, 'com:commentList/com:comment');
                                     foreach ($contentPath as $comment) {
-                                        $commentModel = $docSheet->getComment((string) $comment['ref']);
-                                        if (!empty($comment['authorId'])) {
-                                            $commentModel->setAuthor($authors[(int) $comment['authorId']]);
+                                        $commentx = $comment->attributes();
+                                        $commentModel = $docSheet->getComment((string) $commentx['ref']);
+                                        if (isset($commentx['authorId'])) {
+                                            $commentModel->setAuthor($authors[(int) $commentx['authorId']]);
                                         }
                                         $commentModel->setText($this->parseRichText($comment->children($mainNS)->text));
                                     }

tests/PhpSpreadsheetTests/Reader/Xlsx/CommentTest.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx;
+use PHPUnit\Framework\TestCase;
+
+class CommentTest extends TestCase
+{
+    public function testIssue2316(): void
+    {
+        $filename = 'tests/data/Reader/XLSX/issue.2316.xlsx';
+        $reader = new Xlsx();
+        $spreadsheet = $reader->load($filename);
+
+        $sheet = $spreadsheet->getActiveSheet();
+        $comment = $sheet->getComment('A1');
+        $commentString = (string) $comment;
+        self::assertStringContainsString('編號長度限制：', $commentString);
+        self::assertSame('jill.chen', $comment->getAuthor());
+        $comment = $sheet->getComment('E1');
+        $commentString = (string) $comment;
+        self::assertStringContainsString('若為宅配物流僅能選「純配送」', $commentString);
+        self::assertSame('Anderson Chen 陳宗棠', $comment->getAuthor());
+    }
+}