diff --git a/tests/lib/Cache/FileCacheTest.php b/tests/lib/Cache/FileCacheTest.php
index 1d12147af0d..8d3db539dd0 100644
--- a/tests/lib/Cache/FileCacheTest.php
+++ b/tests/lib/Cache/FileCacheTest.php
@@ -88,7 +88,7 @@ class FileCacheTest extends TestCache {
 
 	private function setupMockStorage() {
 		$mockStorage = $this->getMockBuilder(Local::class)
-			->setMethods(['filemtime', 'unlink'])
+			->onlyMethods(['filemtime', 'unlink'])
 			->setConstructorArgs([['datadir' => \OC::$server->getTempManager()->getTemporaryFolder()]])
 			->getMock();
 
@@ -125,7 +125,7 @@ class FileCacheTest extends TestCache {
 		$this->instance->gc();
 	}
 
-	public function lockExceptionProvider() {
+	public static function lockExceptionProvider(): array {
 		return [
 			[new \OCP\Lock\LockedException('key1')],
 			[new \OCP\Files\LockNotAcquiredException('key1', 1)],
diff --git a/tests/lib/Calendar/ManagerTest.php b/tests/lib/Calendar/ManagerTest.php
index cecebcfc4cf..1fb64d97f47 100644
--- a/tests/lib/Calendar/ManagerTest.php
+++ b/tests/lib/Calendar/ManagerTest.php
@@ -199,7 +199,7 @@ class ManagerTest extends TestCase {
 		$this->assertEquals($expected, $result);
 	}
 
-	public function searchProvider() {
+	public static function searchProvider(): array {
 		$search1 = [
 			[
 				'id' => 1,
@@ -1096,7 +1096,7 @@ class ManagerTest extends TestCase {
 				$this->userManager,
 				$this->serverFactory,
 			])
-			->setMethods([
+			->onlyMethods([
 				'getCalendarsForPrincipal'
 			])
 			->getMock();
@@ -1544,11 +1544,11 @@ class ManagerTest extends TestCase {
 				$this->userManager,
 				$this->serverFactory,
 			])
-			->setMethods([
+			->onlyMethods([
 				'getCalendarsForPrincipal'
 			])
 			->getMock();
-		
+
 		$principalUri = 'principals/user/pierre';
 		$sender = 'clint@stardew-tent-living.com';
 		$recipient = 'pierre@general-store.com';
@@ -1588,7 +1588,7 @@ class ManagerTest extends TestCase {
 				$this->userManager,
 				$this->serverFactory,
 			])
-			->setMethods([
+			->onlyMethods([
 				'getCalendarsForPrincipal'
 			])
 			->getMock();
diff --git a/tests/lib/Encryption/EncryptionWrapperTest.php b/tests/lib/Encryption/EncryptionWrapperTest.php
index 1ac7342a3d8..e661b0481f9 100644
--- a/tests/lib/Encryption/EncryptionWrapperTest.php
+++ b/tests/lib/Encryption/EncryptionWrapperTest.php
@@ -10,10 +10,13 @@ namespace Test\Encryption;
 use OC\Encryption\EncryptionWrapper;
 use OC\Encryption\Manager;
 use OC\Memcache\ArrayCache;
+use OCP\Files\Mount\IMountPoint;
 use OCP\Files\Storage\IDisableEncryptionStorage;
 use OCP\Files\Storage\IStorage;
 use Psr\Log\LoggerInterface;
 use Test\TestCase;
+use OCA\Files_Trashbin\Storage;
+use OC\Files\Storage\Wrapper\Encryption;
 
 class EncryptionWrapperTest extends TestCase {
 	/** @var EncryptionWrapper */
@@ -55,7 +58,7 @@ class EncryptionWrapperTest extends TestCase {
 				]);
 		}
 
-		$mount = $this->getMockBuilder('OCP\Files\Mount\IMountPoint')
+		$mount = $this->getMockBuilder(IMountPoint::class)
 			->disableOriginalConstructor()
 			->getMock();
 
@@ -63,16 +66,16 @@ class EncryptionWrapperTest extends TestCase {
 
 		$this->assertEquals(
 			$expectedWrapped,
-			$returnedStorage->instanceOfStorage('OC\Files\Storage\Wrapper\Encryption'),
+			$returnedStorage->instanceOfStorage(Encryption::class),
 			'Asserted that the storage is (not) wrapped with encryption'
 		);
 	}
 
-	public function provideWrapStorage() {
+	public static function provideWrapStorage(): array {
 		return [
 			// Wrap when not wrapped or not wrapped with storage
 			[true, []],
-			[true, ['OCA\Files_Trashbin\Storage']],
+			[true, [Storage::class]],
 
 			// Do not wrap shared storages
 			[false, [IDisableEncryptionStorage::class]],
diff --git a/tests/lib/Encryption/UpdateTest.php b/tests/lib/Encryption/UpdateTest.php
index 9940549981f..4f3de2b495d 100644
--- a/tests/lib/Encryption/UpdateTest.php
+++ b/tests/lib/Encryption/UpdateTest.php
@@ -113,12 +113,7 @@ class UpdateTest extends TestCase {
 		$updateMock->update($node);
 	}
 
-	/**
-	 * data provider for testUpdate()
-	 *
-	 * @return array
-	 */
-	public function dataTestUpdate() {
+	public static function dataTestUpdate(): array {
 		return [
 			['/user/files/foo', true, ['/user/files/foo/file1.txt', '/user/files/foo/file1.txt'], 2],
 			['/user/files/test.txt', false, [], 1],
@@ -152,12 +147,7 @@ class UpdateTest extends TestCase {
 		$updateMock->postRename($sourceNode, $targetNode);
 	}
 
-	/**
-	 * test data for testPostRename()
-	 *
-	 * @return array
-	 */
-	public function dataTestPostRename() {
+	public static function dataTestPostRename(): array {
 		return [
 			['/test.txt', '/testNew.txt'],
 			['/folder/test.txt', '/testNew.txt'],
@@ -193,6 +183,8 @@ class UpdateTest extends TestCase {
 					$this->logger,
 					$this->uid
 				]
-			)->setMethods($methods)->getMock();
+			)
+			->onlyMethods($methods)
+			->getMock();
 	}
 }
diff --git a/tests/lib/Encryption/UtilTest.php b/tests/lib/Encryption/UtilTest.php
index 62ef809a867..68989c55fb0 100644
--- a/tests/lib/Encryption/UtilTest.php
+++ b/tests/lib/Encryption/UtilTest.php
@@ -20,7 +20,7 @@ class UtilTest extends TestCase {
 	 *
 	 * @see https://bugs.php.net/bug.php?id=21641
 	 */
-	protected int $headerSize = 8192;
+	protected static int $headerSize = 8192;
 
 	/** @var \PHPUnit\Framework\MockObject\MockObject */
 	protected $view;
@@ -61,7 +61,7 @@ class UtilTest extends TestCase {
 		$this->assertEquals($expected, $id);
 	}
 
-	public function providesHeadersForEncryptionModule() {
+	public static function providesHeadersForEncryptionModule(): array {
 		return [
 			['', []],
 			['', ['1']],
@@ -80,11 +80,11 @@ class UtilTest extends TestCase {
 		$this->assertEquals($expected, $result);
 	}
 
-	public function providesHeaders() {
+	public static function providesHeaders(): array {
 		return [
-			[str_pad('HBEGIN:oc_encryption_module:0:HEND', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('HBEGIN:oc_encryption_module:0:HEND', self::$headerSize, '-', STR_PAD_RIGHT)
 				, [], '0'],
-			[str_pad('HBEGIN:oc_encryption_module:0:custom_header:foo:HEND', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('HBEGIN:oc_encryption_module:0:custom_header:foo:HEND', self::$headerSize, '-', STR_PAD_RIGHT)
 				, ['custom_header' => 'foo'], '0'],
 		];
 	}
@@ -120,7 +120,7 @@ class UtilTest extends TestCase {
 		);
 	}
 
-	public function providePathsForTestIsExcluded() {
+	public static function providePathsForTestIsExcluded(): array {
 		return [
 			['/files_encryption', '', true],
 			['files_encryption/foo.txt', '', true],
@@ -152,7 +152,7 @@ class UtilTest extends TestCase {
 		);
 	}
 
-	public function dataTestIsFile() {
+	public static function dataTestIsFile(): array {
 		return [
 			['/user/files/test.txt', true],
 			['/user/files', true],
@@ -175,7 +175,7 @@ class UtilTest extends TestCase {
 			$this->util->stripPartialFileExtension($path));
 	}
 
-	public function dataTestStripPartialFileExtension() {
+	public static function dataTestStripPartialFileExtension(): array {
 		return [
 			['/foo/test.txt', '/foo/test.txt'],
 			['/foo/test.txt.part', '/foo/test.txt'],
@@ -196,17 +196,17 @@ class UtilTest extends TestCase {
 		}
 	}
 
-	public function dataTestParseRawHeader() {
+	public static function dataTestParseRawHeader(): array {
 		return [
-			[str_pad('HBEGIN:oc_encryption_module:0:HEND', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('HBEGIN:oc_encryption_module:0:HEND', self::$headerSize, '-', STR_PAD_RIGHT)
 				, [Util::HEADER_ENCRYPTION_MODULE_KEY => '0']],
-			[str_pad('HBEGIN:oc_encryption_module:0:custom_header:foo:HEND', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('HBEGIN:oc_encryption_module:0:custom_header:foo:HEND', self::$headerSize, '-', STR_PAD_RIGHT)
 				, ['custom_header' => 'foo', Util::HEADER_ENCRYPTION_MODULE_KEY => '0']],
-			[str_pad('HelloWorld', $this->headerSize, '-', STR_PAD_RIGHT), []],
+			[str_pad('HelloWorld', self::$headerSize, '-', STR_PAD_RIGHT), []],
 			['', []],
-			[str_pad('HBEGIN:oc_encryption_module:0', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('HBEGIN:oc_encryption_module:0', self::$headerSize, '-', STR_PAD_RIGHT)
 				, []],
-			[str_pad('oc_encryption_module:0:HEND', $this->headerSize, '-', STR_PAD_RIGHT)
+			[str_pad('oc_encryption_module:0:HEND', self::$headerSize, '-', STR_PAD_RIGHT)
 				, []],
 		];
 	}
@@ -245,7 +245,7 @@ class UtilTest extends TestCase {
 		);
 	}
 
-	public function dataTestGetFileKeyDir() {
+	public static function dataTestGetFileKeyDir(): array {
 		return [
 			[false, '', '/user1/files_encryption/keys/foo/bar.txt/OC_DEFAULT_MODULE/'],
 			[true, '', '/files_encryption/keys/foo/bar.txt/OC_DEFAULT_MODULE/'],
diff --git a/tests/lib/GlobalScale/ConfigTest.php b/tests/lib/GlobalScale/ConfigTest.php
index aa001268ecd..b6c77c9ddf1 100644
--- a/tests/lib/GlobalScale/ConfigTest.php
+++ b/tests/lib/GlobalScale/ConfigTest.php
@@ -28,7 +28,7 @@ class ConfigTest extends TestCase {
 		if (!empty($mockMethods)) {
 			return $this->getMockBuilder(Config::class)
 				->setConstructorArgs([$this->config])
-				->setMethods($mockMethods)
+				->onlyMethods($mockMethods)
 				->getMock();
 		}
 
@@ -64,7 +64,7 @@ class ConfigTest extends TestCase {
 		$this->assertSame($expected, $gsConfig->onlyInternalFederation());
 	}
 
-	public function dataTestOnlyInternalFederation() {
+	public static function dataTestOnlyInternalFederation(): array {
 		return [
 			[true, 'global', false],
 			[true, 'internal', true],
diff --git a/tests/lib/Group/ManagerTest.php b/tests/lib/Group/ManagerTest.php
index 0f8d7a5ecc3..e52e0733501 100644
--- a/tests/lib/Group/ManagerTest.php
+++ b/tests/lib/Group/ManagerTest.php
@@ -12,6 +12,11 @@ use OC\Group\Database;
 use OC\User\Manager;
 use OC\User\User;
 use OCP\EventDispatcher\IEventDispatcher;
+use OCP\Group\Backend\ABackend;
+use OCP\Group\Backend\IAddToGroupBackend;
+use OCP\Group\Backend\ICreateGroupBackend;
+use OCP\Group\Backend\IGroupDetailsBackend;
+use OCP\Group\Backend\IRemoveFromGroupBackend;
 use OCP\Group\Backend\ISearchableGroupBackend;
 use OCP\GroupInterface;
 use OCP\ICacheFactory;
@@ -21,7 +26,8 @@ use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Log\LoggerInterface;
 use Test\TestCase;
 
-interface ISearchableGroupInterface extends ISearchableGroupBackend, GroupInterface {
+abstract class TestBackend extends ABackend implements ISearchableGroupBackend, IAddToGroupBackend, ICreateGroupBackend, IGroupDetailsBackend, IRemoveFromGroupBackend, GroupInterface {
+
 }
 
 class ManagerTest extends TestCase {
@@ -74,9 +80,9 @@ class ManagerTest extends TestCase {
 		}
 		// need to declare it this way due to optional methods
 		// thanks to the implementsActions logic
-		$backend = $this->getMockBuilder(ISearchableGroupInterface::class)
+		$backend = $this->getMockBuilder(TestBackend::class)
 			->disableOriginalConstructor()
-			->setMethods([
+			->onlyMethods([
 				'getGroupDetails',
 				'implementsActions',
 				'getUserGroups',
@@ -283,9 +289,10 @@ class ManagerTest extends TestCase {
 			->with('1')
 			->willReturn(['group1']);
 		$backend->expects($this->once())
-			->method('groupExists')
-			->with('group1')
-			->willReturn(true);
+			->method('getGroupDetails')
+			->willReturnMap([
+				['group1', ['displayName' => 'group1']],
+			]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger, $this->cache, $this->remoteIpAddress);
 		$manager->addBackend($backend);
@@ -306,8 +313,11 @@ class ManagerTest extends TestCase {
 			->with('1')
 			->willReturn(['group1']);
 		$backend1->expects($this->any())
-			->method('groupExists')
-			->willReturn(true);
+			->method('getGroupDetails')
+			->willReturnMap([
+				['group1', ['displayName' => 'group1']],
+				['group12', []],
+			]);
 
 		/**
 		 * @var \PHPUnit\Framework\MockObject\MockObject | \OC\Group\Backend $backend2
@@ -318,8 +328,11 @@ class ManagerTest extends TestCase {
 			->with('1')
 			->willReturn(['group12', 'group1']);
 		$backend2->expects($this->any())
-			->method('groupExists')
-			->willReturn(true);
+			->method('getGroupDetails')
+			->willReturnMap([
+				['group12', ['displayName' => 'group12']],
+				['group1', ['displayName' => 'group1']],
+			]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger, $this->cache, $this->remoteIpAddress);
 		$manager->addBackend($backend1);
@@ -335,7 +348,7 @@ class ManagerTest extends TestCase {
 
 	public function testSearchMultipleBackendsLimitAndOffset(): void {
 		/**
-		 * @var \PHPUnit\Framework\MockObject\MockObject | \OC\Group\Backend $backend1
+		 * @var \PHPUnit\Framework\MockObject\MockObject|\OC\Group\Backend $backend1
 		 */
 		$backend1 = $this->getTestBackend();
 		$backend1->expects($this->once())
@@ -343,11 +356,16 @@ class ManagerTest extends TestCase {
 			->with('1', 2, 1)
 			->willReturn(['group1']);
 		$backend1->expects($this->any())
-			->method('groupExists')
-			->willReturn(true);
+			->method('getGroupDetails')
+			->willReturnMap([
+				[1, []],
+				[2, []],
+				['group1', ['displayName' => 'group1']],
+				['group12', []],
+			]);
 
 		/**
-		 * @var \PHPUnit\Framework\MockObject\MockObject | \OC\Group\Backend $backend2
+		 * @var \PHPUnit\Framework\MockObject\MockObject|\OC\Group\Backend $backend2
 		 */
 		$backend2 = $this->getTestBackend();
 		$backend2->expects($this->once())
@@ -355,8 +373,13 @@ class ManagerTest extends TestCase {
 			->with('1', 2, 1)
 			->willReturn(['group12']);
 		$backend2->expects($this->any())
-			->method('groupExists')
-			->willReturn(true);
+			->method('getGroupDetails')
+			->willReturnMap([
+				[1, []],
+				[2, []],
+				['group1', []],
+				['group12', ['displayName' => 'group12']],
+			]);
 
 		$manager = new \OC\Group\Manager($this->userManager, $this->dispatcher, $this->logger, $this->cache, $this->remoteIpAddress);
 		$manager->addBackend($backend1);