diff --git a/apps/files_versions/tests/BackgroundJob/ExpireVersionsTest.php b/apps/files_versions/tests/BackgroundJob/ExpireVersionsTest.php
index 7a35e9f5f39b1..21e88e86f9054 100644
--- a/apps/files_versions/tests/BackgroundJob/ExpireVersionsTest.php
+++ b/apps/files_versions/tests/BackgroundJob/ExpireVersionsTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2021 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
@@ -16,17 +18,10 @@
 use Test\TestCase;
 
 class ExpireVersionsTest extends TestCase {
-	/** @var IConfig|MockObject */
-	private $config;
-
-	/** @var IUserManager|MockObject */
-	private $userManager;
-
-	/** @var Expiration|MockObject */
-	private $expiration;
-
-	/** @var IJobList|MockObject */
-	private $jobList;
+	private IConfig&MockObject $config;
+	private IUserManager&MockObject $userManager;
+	private Expiration&MockObject $expiration;
+	private IJobList&MockObject $jobList;
 
 	protected function setUp(): void {
 		parent::setUp();
diff --git a/apps/files_versions/tests/Command/CleanupTest.php b/apps/files_versions/tests/Command/CleanupTest.php
index 62d9576e9c505..b0a5c0ca26890 100644
--- a/apps/files_versions/tests/Command/CleanupTest.php
+++ b/apps/files_versions/tests/Command/CleanupTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2017-2024 Nextcloud GmbH and Nextcloud contributors
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
@@ -8,11 +10,13 @@
 
 use OC\User\Manager;
 use OCA\Files_Versions\Command\CleanUp;
+use OCA\Files_Versions\Db\VersionsMapper;
 use OCP\Files\Cache\ICache;
 use OCP\Files\Folder;
 use OCP\Files\IRootFolder;
 use OCP\Files\Storage\IStorage;
 use OCP\UserInterface;
+use PHPUnit\Framework\MockObject\MockObject;
 use Test\TestCase;
 
 /**
@@ -23,28 +27,17 @@
  * @package OCA\Files_Versions\Tests\Command
  */
 class CleanupTest extends TestCase {
-
-	/** @var CleanUp */
-	protected $cleanup;
-
-	/** @var \PHPUnit\Framework\MockObject\MockObject | Manager */
-	protected $userManager;
-
-	/** @var \PHPUnit\Framework\MockObject\MockObject | IRootFolder */
-	protected $rootFolder;
-
-	/** @var \PHPUnit\Framework\MockObject\MockObject | VersionsMapper */
-	protected $versionMapper;
+	protected Manager&MockObject $userManager;
+	protected IRootFolder&MockObject $rootFolder;
+	protected VersionsMapper&MockObject $versionMapper;
+	protected CleanUp $cleanup;
 
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->rootFolder = $this->getMockBuilder('OCP\Files\IRootFolder')
-			->disableOriginalConstructor()->getMock();
-		$this->userManager = $this->getMockBuilder('OC\User\Manager')
-			->disableOriginalConstructor()->getMock();
-		$this->versionMapper = $this->getMockBuilder('OCA\Files_Versions\Db\VersionsMapper')
-			->disableOriginalConstructor()->getMock();
+		$this->rootFolder = $this->createMock(IRootFolder::class);
+		$this->userManager = $this->createMock(Manager::class);
+		$this->versionMapper = $this->createMock(VersionsMapper::class);
 
 		$this->cleanup = new CleanUp($this->rootFolder, $this->userManager, $this->versionMapper);
 	}
@@ -53,7 +46,7 @@ protected function setUp(): void {
 	 * @dataProvider dataTestDeleteVersions
 	 * @param boolean $nodeExists
 	 */
-	public function testDeleteVersions($nodeExists): void {
+	public function testDeleteVersions(bool $nodeExists): void {
 		$this->rootFolder->expects($this->once())
 			->method('nodeExists')
 			->with('/testUser/files_versions')
@@ -92,7 +85,7 @@ public function testDeleteVersions($nodeExists): void {
 		$this->invokePrivate($this->cleanup, 'deleteVersions', ['testUser']);
 	}
 
-	public function dataTestDeleteVersions() {
+	public static function dataTestDeleteVersions(): array {
 		return [
 			[true],
 			[false]
@@ -106,8 +99,8 @@ public function dataTestDeleteVersions() {
 	public function testExecuteDeleteListOfUsers(): void {
 		$userIds = ['user1', 'user2', 'user3'];
 
-		$instance = $this->getMockBuilder('OCA\Files_Versions\Command\CleanUp')
-			->setMethods(['deleteVersions'])
+		$instance = $this->getMockBuilder(CleanUp::class)
+			->onlyMethods(['deleteVersions'])
 			->setConstructorArgs([$this->rootFolder, $this->userManager, $this->versionMapper])
 			->getMock();
 		$instance->expects($this->exactly(count($userIds)))
@@ -119,14 +112,12 @@ public function testExecuteDeleteListOfUsers(): void {
 		$this->userManager->expects($this->exactly(count($userIds)))
 			->method('userExists')->willReturn(true);
 
-		$inputInterface = $this->getMockBuilder('\Symfony\Component\Console\Input\InputInterface')
-			->disableOriginalConstructor()->getMock();
+		$inputInterface = $this->createMock(\Symfony\Component\Console\Input\InputInterface::class);
 		$inputInterface->expects($this->once())->method('getArgument')
 			->with('user_id')
 			->willReturn($userIds);
 
-		$outputInterface = $this->getMockBuilder('\Symfony\Component\Console\Output\OutputInterface')
-			->disableOriginalConstructor()->getMock();
+		$outputInterface = $this->createMock(\Symfony\Component\Console\Output\OutputInterface::class);
 
 		$this->invokePrivate($instance, 'execute', [$inputInterface, $outputInterface]);
 	}
@@ -138,8 +129,8 @@ public function testExecuteAllUsers(): void {
 		$userIds = [];
 		$backendUsers = ['user1', 'user2'];
 
-		$instance = $this->getMockBuilder('OCA\Files_Versions\Command\CleanUp')
-			->setMethods(['deleteVersions'])
+		$instance = $this->getMockBuilder(CleanUp::class)
+			->onlyMethods(['deleteVersions'])
 			->setConstructorArgs([$this->rootFolder, $this->userManager, $this->versionMapper])
 			->getMock();
 
@@ -155,14 +146,12 @@ public function testExecuteAllUsers(): void {
 				$this->assertTrue(in_array($user, $backendUsers));
 			});
 
-		$inputInterface = $this->getMockBuilder('\Symfony\Component\Console\Input\InputInterface')
-			->disableOriginalConstructor()->getMock();
+		$inputInterface = $this->createMock(\Symfony\Component\Console\Input\InputInterface::class);
 		$inputInterface->expects($this->once())->method('getArgument')
 			->with('user_id')
 			->willReturn($userIds);
 
-		$outputInterface = $this->getMockBuilder('\Symfony\Component\Console\Output\OutputInterface')
-			->disableOriginalConstructor()->getMock();
+		$outputInterface = $this->createMock(\Symfony\Component\Console\Output\OutputInterface::class);
 
 		$this->userManager->expects($this->once())
 			->method('getBackends')
diff --git a/apps/files_versions/tests/Command/ExpireTest.php b/apps/files_versions/tests/Command/ExpireTest.php
index 11f4eb2e2be37..b74457a7fd68a 100644
--- a/apps/files_versions/tests/Command/ExpireTest.php
+++ b/apps/files_versions/tests/Command/ExpireTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
diff --git a/apps/files_versions/tests/Controller/PreviewControllerTest.php b/apps/files_versions/tests/Controller/PreviewControllerTest.php
index 0e36703d5aa30..542ea2b6b3485 100644
--- a/apps/files_versions/tests/Controller/PreviewControllerTest.php
+++ b/apps/files_versions/tests/Controller/PreviewControllerTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2016 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
@@ -12,7 +14,6 @@
 use OCP\AppFramework\Http\DataResponse;
 use OCP\Files\File;
 use OCP\Files\Folder;
-use OCP\Files\IMimeTypeDetector;
 use OCP\Files\IRootFolder;
 use OCP\Files\NotFoundException;
 use OCP\Files\SimpleFS\ISimpleFile;
@@ -25,29 +26,14 @@
 use Test\TestCase;
 
 class PreviewControllerTest extends TestCase {
-
-	/** @var IRootFolder|\PHPUnit\Framework\MockObject\MockObject */
-	private $rootFolder;
-
-	/** @var string */
-	private $userId;
-
-	/** @var IMimeTypeDetector|\PHPUnit\Framework\MockObject\MockObject */
-	private $mimeTypeDetector;
-
-	/** @var IPreview|\PHPUnit\Framework\MockObject\MockObject */
-	private $previewManager;
-
-	/** @var PreviewController|\PHPUnit\Framework\MockObject\MockObject */
-	private $controller;
-
-	/** @var IUserSession|\PHPUnit\Framework\MockObject\MockObject */
-	private $userSession;
-
-	/** @var IVersionManager|\PHPUnit\Framework\MockObject\MockObject */
-	private $versionManager;
+	private IRootFolder&MockObject $rootFolder;
+	private string $userId;
+	private IPreview&MockObject $previewManager;
+	private IUserSession&MockObject $userSession;
+	private IVersionManager&MockObject $versionManager;
 
 	private IMimeIconProvider&MockObject $mimeIconProvider;
+	private PreviewController $controller;
 
 	protected function setUp(): void {
 		parent::setUp();
diff --git a/apps/files_versions/tests/ExpirationTest.php b/apps/files_versions/tests/ExpirationTest.php
index ac8af7c093ae0..866e486174134 100644
--- a/apps/files_versions/tests/ExpirationTest.php
+++ b/apps/files_versions/tests/ExpirationTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
@@ -15,7 +17,7 @@
 class ExpirationTest extends \Test\TestCase {
 	public const SECONDS_PER_DAY = 86400; //60*60*24
 
-	public function expirationData() {
+	public static function expirationData(): array {
 		$today = 100 * self::SECONDS_PER_DAY;
 		$back10Days = (100 - 10) * self::SECONDS_PER_DAY;
 		$back20Days = (100 - 20) * self::SECONDS_PER_DAY;
@@ -81,14 +83,8 @@ public function expirationData() {
 
 	/**
 	 * @dataProvider expirationData
-	 *
-	 * @param string $retentionObligation
-	 * @param int $timeNow
-	 * @param int $timestamp
-	 * @param bool $quotaExceeded
-	 * @param string $expectedResult
 	 */
-	public function testExpiration($retentionObligation, $timeNow, $timestamp, $quotaExceeded, $expectedResult): void {
+	public function testExpiration(string $retentionObligation, int $timeNow, int $timestamp, bool $quotaExceeded, bool $expectedResult): void {
 		$mockedConfig = $this->getMockedConfig($retentionObligation);
 		$mockedTimeFactory = $this->getMockedTimeFactory($timeNow);
 		$mockedLogger = $this->createMock(LoggerInterface::class);
@@ -100,11 +96,7 @@ public function testExpiration($retentionObligation, $timeNow, $timestamp, $quot
 	}
 
 
-	/**
-	 * @param int $time
-	 * @return ITimeFactory|MockObject
-	 */
-	private function getMockedTimeFactory($time) {
+	private function getMockedTimeFactory(int $time): ITimeFactory&MockObject {
 		$mockedTimeFactory = $this->createMock(ITimeFactory::class);
 		$mockedTimeFactory->expects($this->any())
 			->method('getTime')
@@ -113,11 +105,7 @@ private function getMockedTimeFactory($time) {
 		return $mockedTimeFactory;
 	}
 
-	/**
-	 * @param string $returnValue
-	 * @return IConfig|MockObject
-	 */
-	private function getMockedConfig($returnValue) {
+	private function getMockedConfig(string $returnValue): IConfig&MockObject {
 		$mockedConfig = $this->createMock(IConfig::class);
 		$mockedConfig->expects($this->any())
 			->method('getSystemValue')
diff --git a/apps/files_versions/tests/StorageTest.php b/apps/files_versions/tests/StorageTest.php
index dd5b94c7a22d2..592f03f5e6304 100644
--- a/apps/files_versions/tests/StorageTest.php
+++ b/apps/files_versions/tests/StorageTest.php
@@ -24,7 +24,7 @@ class StorageTest extends TestCase {
 
 	private $versionsRoot;
 	private $userFolder;
-	private $expireTimestamp = 10;
+	private int $expireTimestamp = 10;
 
 	protected function setUp(): void {
 		parent::setUp();
@@ -46,7 +46,7 @@ protected function setUp(): void {
 	}
 
 
-	protected function createPastFile(string $path, int $mtime) {
+	protected function createPastFile(string $path, int $mtime): void {
 		try {
 			$file = $this->userFolder->get($path);
 		} catch (NotFoundException $e) {
diff --git a/apps/files_versions/tests/VersioningTest.php b/apps/files_versions/tests/VersioningTest.php
index eaa0a02e2612a..659b2cff10c35 100644
--- a/apps/files_versions/tests/VersioningTest.php
+++ b/apps/files_versions/tests/VersioningTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * SPDX-FileCopyrightText: 2016 Nextcloud GmbH and Nextcloud contributors
  * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
@@ -163,7 +165,7 @@ public function testGetExpireList($versions, $sizeOfAllDeletedFiles): void {
 		}
 	}
 
-	public function versionsProvider() {
+	public static function versionsProvider(): array {
 		return [
 			// first set of versions uniformly distributed versions
 			[
@@ -683,7 +685,7 @@ public function testRestoreNoPermission(): void {
 
 		$firstVersion = current($versions);
 
-		$this->assertFalse(Storage::rollback('folder/test.txt', $firstVersion['version'], $this->user2), 'Revert did not happen');
+		$this->assertFalse(Storage::rollback('folder/test.txt', (int)$firstVersion['version'], $this->user2), 'Revert did not happen');
 
 		$this->loginAsUser(self::TEST_VERSIONS_USER);
 
@@ -743,8 +745,8 @@ private function connectMockHooks($hookName, &$params) {
 			return;
 		}
 
-		$eventHandler = $this->getMockBuilder(\stdclass::class)
-			->setMethods(['callback'])
+		$eventHandler = $this->getMockBuilder(DummyHookListener::class)
+			->onlyMethods(['callback'])
 			->getMock();
 
 		$eventHandler->expects($this->any())
@@ -763,7 +765,7 @@ function ($p) use (&$params): void {
 		);
 	}
 
-	private function doTestRestore() {
+	private function doTestRestore(): void {
 		$filePath = self::TEST_VERSIONS_USER . '/files/sub/test.txt';
 		$this->rootView->file_put_contents($filePath, 'test file');
 
@@ -941,11 +943,7 @@ public function testStoreVersionAsAnonymous(): void {
 		);
 	}
 
-	/**
-	 * @param View $view
-	 * @param string $path
-	 */
-	private function createAndCheckVersions(View $view, $path) {
+	private function createAndCheckVersions(View $view, string $path): array {
 		$view->file_put_contents($path, 'test file');
 		$view->file_put_contents($path, 'version 1');
 		$view->file_put_contents($path, 'version 2');
@@ -967,11 +965,7 @@ private function createAndCheckVersions(View $view, $path) {
 		return $versions;
 	}
 
-	/**
-	 * @param string $user
-	 * @param bool $create
-	 */
-	public static function loginHelper($user, $create = false) {
+	public static function loginHelper(string $user, bool $create = false) {
 		if ($create) {
 			$backend = new \Test\Util\User\Dummy();
 			$backend->createUser($user, $user);
@@ -987,6 +981,11 @@ public static function loginHelper($user, $create = false) {
 	}
 }
 
+class DummyHookListener {
+	public function callback() {
+	}
+}
+
 // extend the original class to make it possible to test protected methods
 class VersionStorageToTest extends Storage {
 
diff --git a/apps/files_versions/tests/Versions/VersionManagerTest.php b/apps/files_versions/tests/Versions/VersionManagerTest.php
index 8001d9fbf0e3c..79caa65d5f1f7 100644
--- a/apps/files_versions/tests/Versions/VersionManagerTest.php
+++ b/apps/files_versions/tests/Versions/VersionManagerTest.php
@@ -6,7 +6,7 @@
  * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
-namespace OCA\files_versions\tests\Versions;
+namespace OCA\Files_Versions\Tests\Versions;
 
 use OC\Files\Storage\Local;
 use OCA\Files_Versions\Events\VersionRestoredEvent;
@@ -15,6 +15,7 @@
 use OCA\Files_Versions\Versions\VersionManager;
 use OCP\EventDispatcher\IEventDispatcher;
 use OCP\Files\Storage\IStorage;
+use PHPUnit\Framework\MockObject\MockObject;
 use Test\TestCase;
 
 class VersionManagerTest extends TestCase {
@@ -25,10 +26,10 @@ private function getBackend(bool $shouldUse = true): IVersionBackend {
 		return $backend;
 	}
 
-	private function getStorage(string $class): IStorage {
+	private function getStorage(string $class): IStorage&MockObject {
 		return $this->getMockBuilder($class)
 			->disableOriginalConstructor()
-			->setMethodsExcept(['instanceOfStorage'])
+			->onlyMethods(array_diff(get_class_methods($class), ['instanceOfStorage']))
 			->getMock();
 	}