Fix OPML import of numeric-string category names (#9552)

fix https://github.com/FreshRSS/FreshRSS/issues/9551
`array_merge()` changes the key value of numeric-string keys

app/Services/ImportService.php

@@ -440,15 +440,11 @@ class FreshRSS_Import_Service {
 			// return several categories and feeds if the outline is a category).
 			[$outline_categories, $outline_categories_to_feeds] = $this->loadFromOutline($outline, $parent_category_name);
 
-			// Then, we merge the initial arrays with the arrays returned by
-			// the outline.
-			$categories_elements = array_merge($categories_elements, $outline_categories);
+			// Then, we merge the initial arrays with the arrays returned by the outline.
+			// Watch out for category names that are numeric strings such as `'90'`:
+			$categories_elements = $categories_elements + $outline_categories;
 
 			foreach ($outline_categories_to_feeds as $category_name => $feeds) {
-				if (!is_string($category_name) ||
-					!is_array($feeds)) {
-					continue;
-				}
 				if (!isset($categories_to_feeds[$category_name])) {
 					$categories_to_feeds[$category_name] = [];
 				}

tests/app/Services/ImportServiceOutlinesTest.php

@@ -0,0 +1,65 @@
+<?php
+declare(strict_types=1);
+
+final class ImportServiceOutlinesTest extends PHPUnit\Framework\TestCase {
+
+	#[\Override]
+	protected function setUp(): void {
+		if (!FreshRSS_Context::hasSystemConf()) {
+			FreshRSS_Context::initSystem();
+		}
+		// Prevents any actual database connection
+		FreshRSS_DatabaseDAO::$dummyConnection = true;
+	}
+
+	/**
+	 * @return array{0:array<array-key,array<string,string>>,1:array<array-key,list<array<string,string>>>}
+	 */
+	private static function loadFromOutlines(string $opml): array {
+		$libopml = new \marienfressinaud\LibOpml\LibOpml(strict: false);
+		$opml_array = $libopml->parseString($opml);
+		$importService = new FreshRSS_Import_Service();
+		$method = new ReflectionMethod($importService, 'loadFromOutlines');
+		/** @var array{0:array<array-key,array<string,string>>,1:array<array-key,list<array<string,string>>>} */
+		return $method->invoke($importService, $opml_array['body'], '');
+	}
+
+	/**
+	 * numeric-string names for categories and feeds must survive OPML parsing and the merging of sibling outlines.
+	 */
+	public function test_numeric_names_are_preserved(): void {
+		[$categories_elements, $categories_to_feeds] = self::loadFromOutlines(<<<'XML'
+			<?xml version="1.0" encoding="UTF-8"?>
+			<opml version="2.0">
+				<head><title>Test</title></head>
+				<body>
+					<outline text="90">
+						<outline text="Feed 90" type="rss" xmlUrl="https://example.net/90.xml" />
+					</outline>
+					<outline text="42">
+						<outline text="42 feed" type="rss" xmlUrl="https://example.net/42.xml" />
+					</outline>
+					<outline text="Github">
+						<outline text="12345" type="rss" xmlUrl="https://example.net/gh.xml" />
+					</outline>
+				</body>
+			</opml>
+			XML);
+
+		self::assertCount(3, $categories_elements);
+		self::assertCount(3, $categories_to_feeds);
+		self::assertSame([90, 42, 'Github'], array_keys($categories_elements), 'Numeric category keys are preserved while merging sibling outlines');
+		self::assertSame('90', $categories_elements[90]['text']);
+		self::assertSame('42', $categories_elements[42]['text']);
+
+		foreach ($categories_to_feeds as $category_name => $feeds) {
+			self::assertCount(1, $feeds, "Category `{$category_name}` keeps its feed");
+		}
+		self::assertSame('Feed 90', $categories_to_feeds[90][0]['text']);
+		self::assertSame('42 feed', $categories_to_feeds[42][0]['text']);
+		self::assertSame('12345', $categories_to_feeds['Github'][0]['text'], 'Numeric feed name is preserved');
+		self::assertSame('https://example.net/90.xml', $categories_to_feeds[90][0]['xmlUrl']);
+		self::assertSame('https://example.net/42.xml', $categories_to_feeds[42][0]['xmlUrl']);
+		self::assertSame('https://example.net/gh.xml', $categories_to_feeds['Github'][0]['xmlUrl']);
+	}
+}