Ignore empty or null comment values (#249)

Author: dimitri-koenig

README.md

@@ -183,6 +183,9 @@ This code will result in:
 </root>
 ```
 
+> [!NOTE]
+> A comment will be omitted if the value is an empty string "" or `null`.
+
 ### Using reserved characters
 
 It is also possible to wrap the value of a node into a CDATA section. This allows you to use reserved characters.

src/ArrayToXml.php

@@ -185,7 +185,9 @@ protected function convertElement(DOMElement $element, mixed $value): void
                 } elseif (str_starts_with($key, '__custom:')) {
                     $this->addNode($element, str_replace('\:', ':', preg_split('/(?<!\\\):/', $key)[1]), $data);
                 } elseif (str_starts_with($key, '_comment') || str_starts_with($key, '@comment')) {
-                    $element->appendChild(new \DOMComment($data));
+                    if ($data !== null && $data !== '') {
+                        $element->appendChild(new \DOMComment($data));
+                    }
                 } else {
                     $this->addNode($element, $key, $data);
                 }

tests/ArrayToXmlTest.php

@@ -187,6 +187,20 @@
     assertMatchesXmlSnapshot(ArrayToXml::convert($withAttributes));
 });
 
+it('null and empty comments are ignored', function () {
+    $withAttributes = $this->testArray;
+    $withAttributes['Another guy'] = [
+        '_comment' => null,
+        'name' => 'John Wick',
+        '_comment2' => '',
+        'weapon' => 'Pencil',
+        '_comment_deaths' => 0,
+        'lives' => 'more than 9 lives'
+    ];
+
+    assertMatchesSnapshot(ArrayToXml::convert($withAttributes, domProperties: ['formatOutput' => true]));
+});
+
 test('and a comment also can be set in SimpleXMLElement style', function () {
     $withAttributes = $this->testArray;
     $withAttributes['Good guy']['@comment'] = 'Very short list';

tests/__snapshots__/ArrayToXmlTest__it_null_and_empty_comments_are_ignored__1.txt

@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<root>
+  <Good_guy>
+    <name>Luke Skywalker</name>
+    <weapon>Lightsaber</weapon>
+  </Good_guy>
+  <Bad_guy>
+    <name>Sauron</name>
+    <weapon>Evil Eye</weapon>
+  </Bad_guy>
+  <Another_guy>
+    <name>John Wick</name>
+    <weapon>Pencil</weapon>
+    <!--0-->
+    <lives>more than 9 lives</lives>
+  </Another_guy>
+</root>