fix: Rewind iterator before calling current/next

lib/Command/Watch.php

@@ -44,7 +44,6 @@ protected function configure() {
 
 	private function getLastLogId() {
 		$logIterator = $this->logIteratorFactory->getLogIterator(self::ALL_LEVELS);
-		$logIterator->next();
 		if ($logIterator->current() !== null) {
 			return $logIterator->current()['reqId'];
 		}
@@ -74,7 +73,6 @@ public function watch(bool $raw, OutputInterface $output): int {
 			$id = $this->getLastLogId();
 			if ($id !== $lastId) {
 				$iterator = $this->logIteratorFactory->getLogIterator(self::ALL_LEVELS);
-				$iterator->next();
 
 				$lines = [];
 

lib/Controller/LogController.php

@@ -71,6 +71,7 @@ public function get($query = '', $count = 50, $offset = 0): JSONResponse {
 	 */
 	private function getLastItem() {
 		$iterator = $this->logIteratorFactory->getLogIterator($this->settingsService->getShownLevels());
+		$iterator->rewind();
 		return $iterator->current();
 	}
 
@@ -102,7 +103,7 @@ public function poll(string $lastReqId): JSONResponse {
 		}
 
 		$iterator = $this->logIteratorFactory->getLogIterator($this->settingsService->getShownLevels());
-		$iterator->next();
+		$iterator->rewind();
 
 		$data = [];
 

tests/Unit/Controller/LogControllerTest.php

@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\LogReader\Tests\Unit\Controller;
+
+use OCA\LogReader\Controller\LogController;
+use OCA\LogReader\Log\LogIterator;
+use OCA\LogReader\Log\LogIteratorFactory;
+use OCA\LogReader\Service\SettingsService;
+use OCP\IRequest;
+use PHPUnit\Framework\MockObject\MockObject;
+use Psr\Log\LoggerInterface;
+use Test\TestCase;
+
+class LogControllerTest extends TestCase {
+
+	private LogController $logController;
+
+	/** @var LogIteratorFactory|MockObject */
+	private $logIteratorFactory;
+
+	/** @var SettingsService|MockObject */
+	private $settingsService;
+
+	/** @var LoggerInterface|MockObject */
+	private $logger;
+
+	/** @var IRequest|MockObject */
+	private $request;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->logIteratorFactory = $this->createStub(LogIteratorFactory::class);
+		$this->settingsService = $this->createStub(SettingsService::class);
+		$this->logger = $this->createStub(LoggerInterface::class);
+		$this->request = $this->createStub(IRequest::class);
+
+		$this->settingsService->method('getLoggingType')->willReturn('file');
+		$this->settingsService->method('getShownLevels')->willReturn([0, 1, 2, 3, 4]);
+
+		$this->logController = new LogController(
+			'logreader',
+			$this->request,
+			$this->logIteratorFactory,
+			$this->settingsService,
+			$this->logger,
+		);
+	}
+
+	private function getLogIterator(string $log): LogIterator {
+		$handle = fopen('php://temp', 'r+');
+		fwrite($handle, $log);
+		rewind($handle);
+		return new LogIterator($handle, \DateTime::ATOM, 'UTC');
+	}
+
+	/**
+	 * Every call to the factory must return a freshly rewound iterator over
+	 * the same log content, mirroring how the real factory opens the log
+	 * file anew for each call.
+	 */
+	private function mockLogWithEntries(string $log): void {
+		$this->logIteratorFactory->method('getLogIterator')
+			->willReturnCallback(fn () => $this->getLogIterator($log));
+	}
+
+	public function testPollIncludesTheNewestLogEntry(): void {
+		$log = '{"reqId":"1","level":3,"time":"2019-11-04T18:50:57+00:00","app":"comments"}' . "\n"
+			. '{"reqId":"2","level":3,"time":"2019-11-04T18:50:58+00:00","app":"gallery"}' . "\n"
+			. '{"reqId":"3","level":3,"time":"2019-11-04T18:50:59+00:00","app":"files"}';
+		$this->mockLogWithEntries($log);
+
+		$response = $this->logController->poll('1');
+		$data = $response->getData();
+
+		$this->assertCount(2, $data);
+		// sorted newest first, the last written entry (reqId 3) must be included
+		$this->assertEquals('3', $data[0]['reqId']);
+		$this->assertEquals('2', $data[1]['reqId']);
+	}
+
+	public function testPollReturnsEmptyWhenThereIsNoNewEntry(): void {
+		$log = '{"reqId":"1","level":3,"time":"2019-11-04T18:50:57+00:00","app":"comments"}';
+		$this->mockLogWithEntries($log);
+
+		$response = $this->logController->poll('1');
+
+		$this->assertEquals([], $response->getData());
+	}
+}