tests: Tests for BBCode cleanup fix

Somehow I forgot to include this in the patch that fixed the issue.

tests/unit/CleanupBBCodeTest.php

@@ -0,0 +1,27 @@
+<?php
+/*
+ * SPDX-FileCopyrightText: 2024 Hubzilla Community
+ * SPDX-FileContributor: Harald Eilertsen
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+namespace Zotlabs\Tests\Unit;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class CleanupBBCodeTest extends UnitTestCase {
+	#[DataProvider("cleanup_bbcode_provider")]
+	public function test_cleanup_bbcode(string $expected, string $input): void {
+		$this->assertEquals($expected, cleanup_bbcode($input));
+	}
+
+	public static function cleanup_bbcode_provider(): array {
+		return [
+			'url followed by newline' => [
+				"#^[url=https://example.com]https://example.com[/url]\na test link",
+				"https://example.com\na test link",
+			]
+		];
+	}
+}