Improve XML element creation and add tests for special character handling (eq. &)

Author: Kris2x

src/XlsxFastEditor.php

@@ -1028,13 +1028,17 @@ public function _makeNewSharedString(string $value): int
 		}
 
 		try {
-			$t = $dom->createElement('t', $value);
+			// First, we create an empty element t
+			$t = $dom->createElement('t');
+			if ($t === false) {
+				throw new XlsxFastEditorXmlException('Failed to create <t> element');
+			}
+			// Add content as a text node
+			$textNode = $dom->createTextNode($value);
+			$t->appendChild($textNode);
 		} catch (\DOMException $dex) {
 			throw new XlsxFastEditorXmlException('Error creating <t> in shared strings!', $dex->code, $dex);
 		}
-		if ($t === false) {
-			throw new XlsxFastEditorXmlException('Error creating <t> in shared strings!');
-		}
 		$si->appendChild($t);
 		if (!($dom->firstElementChild instanceof \DOMElement)) {
 			throw new XlsxFastEditorXmlException('Invalid shared strings!');
@@ -1048,7 +1052,7 @@ public function _makeNewSharedString(string $value): int
 		$dom->firstElementChild->setAttribute('uniqueCount', (string)$uniqueCount);
 
 		$this->touchPath(self::SHARED_STRINGS_PATH);
-		return $uniqueCount - 1;	// Base 0
+		return $uniqueCount - 1; // Base 0
 	}
 
 	/**

tests/test.php

@@ -119,6 +119,9 @@
 	$xlsxFastEditor->writeInt($sheet2, 'C3', -7);
 	$xlsxFastEditor->writeFloat($sheet2, 'D3', 273.15);
 
+	// Test writing special character '&'
+	$xlsxFastEditor->writeString($sheet2, 'A5', '&');
+
 	// Writing non-existing cells but existing lines
 	$xlsxFastEditor->writeFormula($sheet2, 'I2', '=7*3');
 	$xlsxFastEditor->writeString($sheet2, 'F2', 'γ');
@@ -166,6 +169,9 @@
 
 	assert($xlsxFastEditor->readString($sheet1, 'B2') === 'World');
 
+	// Test writing special character '&'
+	assert($xlsxFastEditor->readString($sheet2, 'A5') === '&');
+
 	$xlsxFastEditor->close();
 
 	// Verify by hand that the resulting file opens without warning in Microsoft Excel.