Add test for DiscussionTools TOC additions

We verify that they appear in the action=parse API output.

We should also have a test to verify that they appear in the Vector
2022 skin, but that might have to be done as a browser test.

Bug: T326677
Change-Id: I81d5ddecd3b244aeee8cba71498f4d65f8e53696

tests/phpunit/integration/ApiParseDiscussionToolsTest.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace MediaWiki\Extension\DiscussionTools\Tests;
+
+use ApiTestCase;
+
+/**
+ * @group medium
+ * @group Database
+ */
+class ApiParseDiscussionToolsTest extends ApiTestCase {
+
+	/**
+	 * @covers \MediaWiki\Extension\DiscussionTools\CommentFormatter::addDiscussionTools
+	 */
+	public function testApiParseSections() {
+		$params = [
+			'action' => 'parse',
+			'title' => 'Talk:Test',
+			'uselang' => 'en',
+			'text' => "__FORCETOC__\n== foo ==\nbar ~~~~",
+			'pst' => 1,
+			'prop' => 'sections',
+		];
+
+		[ $result, ] = $this->doApiRequest( $params );
+
+		$this->assertSame(
+			'<span class="ext-discussiontools-init-sidebar-meta">1 comment</span>',
+			$result['parse']['sections'][0]['extensionData']['DiscussionTools-html-summary']
+		);
+	}
+
+}