diff --git a/src/Core/Cache/Type/DatabaseCache.php b/src/Core/Cache/Type/DatabaseCache.php
index efb9a8d03e..8f5b554606 100644
--- a/src/Core/Cache/Type/DatabaseCache.php
+++ b/src/Core/Cache/Type/DatabaseCache.php
@@ -11,6 +11,8 @@ use Friendica\Core\Cache\Capability\ICanCache;
 use Friendica\Core\Cache\Enum;
 use Friendica\Core\Cache\Exception\CachePersistenceException;
 use Friendica\Database\Database;
+use Friendica\DI;
+use Friendica\Repository\CacheRepository;
 use Friendica\Util\DateTimeFormat;
 
 /**
@@ -25,11 +27,16 @@ class DatabaseCache extends AbstractCache implements ICanCache
 	 */
 	private $dba;
 
+	private CacheRepository $cacheRepo;
+
 	public function __construct(string $hostname, Database $dba)
 	{
 		parent::__construct($hostname);
 
 		$this->dba = $dba;
+
+		// #TODO: Replace this with constuctor injection
+		$this->cacheRepo = DI::databaseService()->getCacheRepository();
 	}
 
 	/**
@@ -41,27 +48,14 @@ class DatabaseCache extends AbstractCache implements ICanCache
 	{
 		try {
 			if (empty($prefix)) {
-				$where = ['`expires` >= ?', DateTimeFormat::utcNow()];
+				$keys = $this->cacheRepo->getAllKeysValidUntil(DateTimeFormat::utcNow());
 			} else {
-				$where = ['`expires` >= ? AND `k` LIKE CONCAT(?, \'%\')', DateTimeFormat::utcNow(), $prefix];
+				$keys = $this->cacheRepo->getAllKeysValidUntilWithPrefix(DateTimeFormat::utcNow(), $prefix);
 			}
-
-			$stmt = $this->dba->select('cache', ['k'], $where);
 		} catch (\Exception $exception) {
 			throw new CachePersistenceException(sprintf('Cannot fetch all keys with prefix %s', $prefix), $exception);
 		}
 
-		try {
-			$keys = [];
-			while ($key = $this->dba->fetch($stmt)) {
-				array_push($keys, $key['k']);
-			}
-		} catch (\Exception $exception) {
-			$this->dba->close($stmt);
-			throw new CachePersistenceException(sprintf('Cannot fetch all keys with prefix %s', $prefix), $exception);
-		}
-
-		$this->dba->close($stmt);
 		return $keys;
 	}
 
diff --git a/src/DI.php b/src/DI.php
index bcbc17651b..fa9dfbda78 100644
--- a/src/DI.php
+++ b/src/DI.php
@@ -80,6 +80,11 @@ abstract class DI
 		return self::$dice->create(AppHelper::class);
 	}
 
+	public static function databaseService(): Database\DatabaseService
+	{
+		return self::$dice->create(Database\DatabaseService::class);
+	}
+
 	/**
 	 * @return Database\Database
 	 */
diff --git a/src/Database/Database.php b/src/Database/Database.php
index 88aa636fd3..a2200d9340 100644
--- a/src/Database/Database.php
+++ b/src/Database/Database.php
@@ -62,15 +62,15 @@ class Database
 	protected $server_info = '';
 	/** @var PDO|mysqli|null */
 	protected $connection;
-	protected $driver               = '';
-	protected $pdo_emulate_prepares = false;
-	private $error                  = '';
-	private $errorno                = 0;
-	private $affected_rows          = 0;
-	protected $in_transaction       = false;
-	protected $in_retrial           = false;
-	protected $testmode             = false;
-	private $relation               = [];
+	protected $driver                     = '';
+	protected $pdo_emulate_prepares       = false;
+	private $error                        = '';
+	private $errorno                      = 0;
+	private $affected_rows                = 0;
+	protected $in_transaction             = false;
+	protected $in_retrial                 = false;
+	private bool $throwExceptionsOnErrors = false;
+	private $relation                     = [];
 	/** @var DbaDefinition */
 	protected $dbaDefinition;
 	/** @var ViewDefinition */
@@ -205,9 +205,18 @@ class Database
 		return $this->connected;
 	}
 
-	public function setTestmode(bool $test)
+	/**
+	 * Should errors throwns as exceptions?
+	 *
+	 * @return bool returns the previous value
+	 */
+	public function throwExceptionsOnErrors(bool $throwExceptions): bool
 	{
-		$this->testmode = $test;
+		$prev = $this->throwExceptionsOnErrors;
+
+		$this->throwExceptionsOnErrors = $throwExceptions;
+
+		return $prev;
 	}
 
 	/**
@@ -672,7 +681,7 @@ class Database
 			$error   = $this->error;
 			$errorno = $this->errorno;
 
-			if ($this->testmode) {
+			if ($this->throwExceptionsOnErrors) {
 				throw new DatabaseException($error, $errorno, $this->replaceParameters($sql, $args));
 			}
 
@@ -779,7 +788,7 @@ class Database
 			$error   = $this->error;
 			$errorno = $this->errorno;
 
-			if ($this->testmode) {
+			if ($this->throwExceptionsOnErrors) {
 				throw new DatabaseException($error, $errorno, $this->replaceParameters($sql, $params));
 			}
 
diff --git a/src/Database/DatabaseService.php b/src/Database/DatabaseService.php
new file mode 100644
index 0000000000..eafa7cbf4a
--- /dev/null
+++ b/src/Database/DatabaseService.php
@@ -0,0 +1,36 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Database;
+
+use Friendica\Database\Database;
+use Friendica\Database\Repository\CacheTableRepository;
+use Friendica\Database\Repository\UserdTableRepository;
+use Friendica\Repository\CacheRepository;
+use Friendica\Repository\DeletedUserRepository;
+
+final class DatabaseService
+{
+	private Database $database;
+
+	public function __construct(Database $database)
+	{
+		$this->database = $database;
+	}
+
+	public function getDeletedUserRepository(): DeletedUserRepository
+	{
+		return new UserdTableRepository($this->database);
+	}
+
+	public function getCacheRepository(): CacheRepository
+	{
+		return new CacheTableRepository($this->database);
+	}
+}
diff --git a/src/Database/Model/CacheModel.php b/src/Database/Model/CacheModel.php
new file mode 100644
index 0000000000..9987645616
--- /dev/null
+++ b/src/Database/Model/CacheModel.php
@@ -0,0 +1,83 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Database\Model;
+
+use Exception;
+use Friendica\Database\DBA;
+use Friendica\Entity\CacheEntity;
+
+/**
+ * Model for a row in the cache table
+ */
+final class CacheModel implements CacheEntity
+{
+	/**
+	 * Validates the row array and creates the entity
+	 *
+	 * @throws Exception If $data['v'] contains invalid data that could not unserialize.
+	 */
+	public static function createFromArray(array $data): self
+	{
+		$rawValue = array_key_exists('v', $data) ? (string) $data['v'] : '';
+		$value = @unserialize($rawValue);
+
+		// Only return a value if the serialized value is valid.
+		// We also check if the db entry is a serialized
+		// boolean 'false' value (which we want to return).
+		if ($value === false && $rawValue !== 'b:0;' ) {
+			throw new Exception(sprintf('Invalid value data for cache object.'));
+		}
+
+		$entity = new self();
+		array_key_exists('k', $data) ?? $entity->k = (string) $data['k'];
+		$entity->v = $rawValue;
+		$entity->value = $value;
+		array_key_exists('expired', $data) ?? $entity->expired = (string) $data['expired'];
+		array_key_exists('updated', $data) ?? $entity->updated = (string) $data['updated'];
+
+		return $entity;
+	}
+
+	/**
+	 * cache key
+	 */
+	private string $k = '';
+
+	/**
+	 * cached serialized value
+	 */
+	private string $v = '';
+
+	/**
+	 *
+	 * @var mixed $value cached unserialized value
+	 */
+	private $value;
+
+	/**
+	 * datetime of cache expiration
+	 */
+	private string $expired = DBA::NULL_DATETIME;
+
+	/**
+	 * datetime of cache insertion
+	 */
+	private string $updated = DBA::NULL_DATETIME;
+
+	private function __construct() {}
+
+	/**
+	 * @return mixed
+	 */
+	public function getValue()
+	{
+		return $this->value;
+	}
+}
diff --git a/src/Database/Repository/CacheTableRepository.php b/src/Database/Repository/CacheTableRepository.php
new file mode 100644
index 0000000000..1f0b278ec3
--- /dev/null
+++ b/src/Database/Repository/CacheTableRepository.php
@@ -0,0 +1,135 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Database\Repository;
+
+use Friendica\Database\Database;
+use Friendica\Database\DatabaseException;
+use Friendica\Database\Model\CacheModel;
+use Friendica\Entity\CacheEntity;
+use Friendica\Repository\CacheRepository;
+use Throwable;
+
+/**
+ * Repository for cache table
+ */
+final class CacheTableRepository implements CacheRepository
+{
+	private Database $database;
+
+	public function __construct(Database $database)
+	{
+		$this->database = $database;
+	}
+
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return array<string>
+	 */
+	public function getAllKeysValidUntil(string $expires): array
+	{
+		$throw = $this->database->throwExceptionsOnErrors(true);
+
+		try {
+			return $this->getAllKeys($expires, null);
+		} catch (Throwable $th) {
+			if (! $th instanceof DatabaseException) {
+				$th = new DatabaseException('Cannot fetch all keys without prefix', 0, '', $th);
+			}
+
+			throw $th;
+		} finally {
+			$this->database->throwExceptionsOnErrors($throw);
+		}
+	}
+
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return array<string>
+	 */
+	public function getAllKeysValidUntilWithPrefix(string $expires, string $prefix): array
+	{
+		$throw = $this->database->throwExceptionsOnErrors(true);
+
+		try {
+			return $this->getAllKeys($expires, $prefix);
+		} catch (Throwable $th) {
+			if (! $th instanceof DatabaseException) {
+				$th = new DatabaseException(sprintf('Cannot fetch all keys with prefix `%s`', $prefix), 0, '', $th);
+			}
+
+			throw $th;
+		} finally {
+			$this->database->throwExceptionsOnErrors($throw);
+		}
+	}
+
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return CacheEntity|null
+	 */
+	public function findOneByKeyValidUntil(string $key, string $expires)
+	{
+		$throw = $this->database->throwExceptionsOnErrors(true);
+
+		try {
+			$cacheArray = $this->database->selectFirst(
+				'cache',
+				['v'],
+				['`k` = ? AND (`expires` >= ? OR `expires` = -1)', $key, $expires]
+			);
+
+			if (!$this->database->isResult($cacheArray)) {
+				return null;
+			}
+		} catch (Throwable $th) {
+			if (! $th instanceof DatabaseException) {
+				$th = new DatabaseException(sprintf('Cannot get cache entry with key `%s`', $key), 0, '', $th);
+			}
+
+			throw $th;
+		} finally {
+			$this->database->throwExceptionsOnErrors($throw);
+		}
+
+		try {
+			$entity = CacheModel::createFromArray($cacheArray);
+		} catch (Throwable $th) {
+			return null;
+		}
+
+		return $entity;
+	}
+
+	private function getAllKeys(string $expires, ?string $prefix = null): array
+	{
+		if ($prefix === null) {
+			$where = ['`expires` >= ?', $expires];
+		} else {
+			$where = ['`expires` >= ? AND `k` LIKE CONCAT(?, \'%\')', $expires, $prefix];
+		}
+
+		$stmt = $this->database->select('cache', ['k'], $where);
+
+		$keys = [];
+
+		try {
+			while ($key = $this->database->fetch($stmt)) {
+				array_push($keys, $key['k']);
+			}
+		} finally {
+			$this->database->close($stmt);
+		}
+
+		return $keys;
+	}
+}
diff --git a/src/Database/Repository/UserdTableRepository.php b/src/Database/Repository/UserdTableRepository.php
new file mode 100644
index 0000000000..9095bbfaaa
--- /dev/null
+++ b/src/Database/Repository/UserdTableRepository.php
@@ -0,0 +1,54 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Database\Repository;
+
+use Exception;
+use Friendica\Database\Database;
+use Friendica\Database\DatabaseException;
+use Friendica\Repository\DeletedUserRepository;
+
+/**
+ * Repository for userd table
+ */
+final class UserdTableRepository implements DeletedUserRepository
+{
+	private Database $database;
+
+	public function __construct(Database $database)
+	{
+		$this->database = $database;
+	}
+
+	/**
+	 * Insert a deleted user by username.
+	 *
+	 * @throws DatabaseException If the username could not be inserted
+	 */
+	public function insertByUsername(string $username): void
+	{
+		$throw = $this->database->throwExceptionsOnErrors(true);
+
+		try {
+			$this->database->insert('userd', ['username' => $username]);
+		} finally {
+			$this->database->throwExceptionsOnErrors($throw);
+		}
+	}
+
+	/**
+	 * Check if a deleted username exists.
+	 *
+	 * @throws \Exception
+	 */
+	public function existsByUsername(string $username): bool
+	{
+		return $this->database->exists('userd', ['username' => $username]);
+	}
+}
diff --git a/src/Entity/CacheEntity.php b/src/Entity/CacheEntity.php
new file mode 100644
index 0000000000..d32baee105
--- /dev/null
+++ b/src/Entity/CacheEntity.php
@@ -0,0 +1,21 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Entity;
+
+/**
+ * Entity for a cache entry
+ */
+interface CacheEntity
+{
+	/**
+	 * @return mixed
+	 */
+	public function getValue();
+}
diff --git a/src/Model/User.php b/src/Model/User.php
index 5195fb77a3..dec9400604 100644
--- a/src/Model/User.php
+++ b/src/Model/User.php
@@ -266,10 +266,12 @@ class User
 			return $system_actor_name;
 		}
 
+		$userDeletedRepository = DI::databaseService()->getDeletedUserRepository();
+
 		// List of possible actor names
 		$possible_accounts = ['friendica', 'actor', 'system', 'internal'];
 		foreach ($possible_accounts as $name) {
-			if (!DBA::exists('user', ['nickname' => $name]) && !DBA::exists('userd', ['username' => $name])) {
+			if (!DBA::exists('user', ['nickname' => $name]) && !$userDeletedRepository->existsByUsername($name)) {
 				DI::config()->set('system', 'actor_name', $name);
 				return $name;
 			}
@@ -1299,10 +1301,12 @@ class User
 			throw new Exception(DI::l10n()->t('Your nickname can only contain a-z, 0-9 and _.'));
 		}
 
+		$userDeletedRepository = DI::databaseService()->getDeletedUserRepository();
+
 		// Check existing and deleted accounts for this nickname.
 		if (
 			DBA::exists('user', ['nickname' => $nickname])
-			|| DBA::exists('userd', ['username' => $nickname])
+			|| $userDeletedRepository->existsByUsername($nickname)
 		) {
 			throw new Exception(DI::l10n()->t('Nickname is already registered. Please choose another.'));
 		}
@@ -1812,9 +1816,15 @@ class User
 
 		$user = $hook_data['user'] ?? $user;
 
+		$userDeletedRepository = DI::databaseService()->getDeletedUserRepository();
+
 		// save username (actually the nickname as it is guaranteed
 		// unique), so it cannot be re-registered in the future.
-		DBA::insert('userd', ['username' => $user['nickname']]);
+		try {
+			$userDeletedRepository->insertByUsername($user['nickname']);
+		} catch (\Throwable $th) {
+			DI::logger()->error('Error while inserting username of deleted user.', ['username' => $user['nickname'], 'exception' => $th]);
+		}
 
 		// Remove all personal settings, especially connector settings
 		DBA::delete('pconfig', ['uid' => $uid]);
diff --git a/src/Module/Profile/Profile.php b/src/Module/Profile/Profile.php
index 58f829907e..d437f0579d 100644
--- a/src/Module/Profile/Profile.php
+++ b/src/Module/Profile/Profile.php
@@ -35,6 +35,7 @@ use Friendica\Network\HTTPException;
 use Friendica\Network\HTTPException\InternalServerErrorException;
 use Friendica\Profile\ProfileField\Repository\ProfileField;
 use Friendica\Protocol\ActivityPub;
+use Friendica\Repository\DeletedUserRepository;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Network;
 use Friendica\Util\Profiler;
@@ -47,6 +48,7 @@ class Profile extends BaseProfile
 {
 	/** @var Database */
 	private $database;
+	private DeletedUserRepository $deletedUserRepository;
 	/** @var AppHelper */
 	private $appHelper;
 	/** @var IHandleUserSessions */
@@ -66,6 +68,7 @@ class Profile extends BaseProfile
 		IHandleUserSessions $session,
 		AppHelper $appHelper,
 		Database $database,
+		DeletedUserRepository $deletedUserRepository,
 		EventDispatcherInterface $eventDispatcher,
 		L10n $l10n,
 		BaseURL $baseUrl,
@@ -78,13 +81,14 @@ class Profile extends BaseProfile
 	) {
 		parent::__construct($l10n, $baseUrl, $args, $logger, $profiler, $response, $server, $parameters);
 
-		$this->database        = $database;
-		$this->appHelper       = $appHelper;
-		$this->session         = $session;
-		$this->config          = $config;
-		$this->page            = $page;
-		$this->profileField    = $profileField;
-		$this->eventDispatcher = $eventDispatcher;
+		$this->database              = $database;
+		$this->deletedUserRepository = $deletedUserRepository;
+		$this->appHelper             = $appHelper;
+		$this->session               = $session;
+		$this->config                = $config;
+		$this->page                  = $page;
+		$this->profileField          = $profileField;
+		$this->eventDispatcher       = $eventDispatcher;
 	}
 
 	protected function rawContent(array $request = [])
@@ -102,7 +106,7 @@ class Profile extends BaseProfile
 				}
 			}
 
-			if ($this->database->exists('userd', ['username' => $this->parameters['nickname']])) {
+			if ($this->deletedUserRepository->existsByUsername($this->parameters['nickname'])) {
 				// Known deleted user
 				$data = ActivityPub\Transmitter::getDeletedUser($this->parameters['nickname']);
 
diff --git a/src/Module/User/Import.php b/src/Module/User/Import.php
index 74f2f9b6ad..a3ff223084 100644
--- a/src/Module/User/Import.php
+++ b/src/Module/User/Import.php
@@ -7,7 +7,8 @@
 
 namespace Friendica\Module\User;
 
-use Friendica\App;
+use Friendica\App\Arguments;
+use Friendica\App\BaseURL;
 use Friendica\Core\Config\Capability\IManageConfigValues;
 use Friendica\Core\L10n;
 use Friendica\Core\PConfig\Capability\IManagePersonalConfigValues;
@@ -26,6 +27,7 @@ use Friendica\Navigation\SystemMessages;
 use Friendica\Network\HTTPException;
 use Friendica\Object\Image;
 use Friendica\Protocol\Delivery;
+use Friendica\Repository\DeletedUserRepository;
 use Friendica\Security\PermissionSet\Repository\PermissionSet;
 use Friendica\Util\Profiler;
 use Friendica\Util\Strings;
@@ -47,20 +49,38 @@ class Import extends \Friendica\BaseModule
 	/** @var Database */
 	private $database;
 
+	private DeletedUserRepository $deletedUserRepository;
+
 	/** @var PermissionSet */
 	private $permissionSet;
 
 	/** @var UserSession */
 	private $session;
 
-	public function __construct(UserSession $session, PermissionSet $permissionSet, IManagePersonalConfigValues $pconfig, Database $database, SystemMessages $systemMessages, IManageConfigValues $config, L10n $l10n, App\BaseURL $baseUrl, App\Arguments $args, LoggerInterface $logger, Profiler $profiler, Response $response, array $server, array $parameters = [])
-	{
+	public function __construct(
+		UserSession $session,
+		PermissionSet $permissionSet,
+		IManagePersonalConfigValues $pconfig,
+		Database $database,
+		DeletedUserRepository $deletedUserRepository,
+		SystemMessages $systemMessages,
+		IManageConfigValues $config,
+		L10n $l10n,
+		BaseURL $baseUrl,
+		Arguments $args,
+		LoggerInterface $logger,
+		Profiler $profiler,
+		Response $response,
+		array $server,
+		array $parameters = []
+	) {
 		parent::__construct($l10n, $baseUrl, $args, $logger, $profiler, $response, $server, $parameters);
 
 		$this->config         = $config;
 		$this->pconfig        = $pconfig;
 		$this->systemMessages = $systemMessages;
 		$this->database       = $database;
+		$this->deletedUserRepository = $deletedUserRepository;
 		$this->permissionSet  = $permissionSet;
 		$this->session        = $session;
 	}
@@ -213,7 +233,7 @@ class Import extends \Friendica\BaseModule
 		// check for username
 		// check if username matches deleted account
 		if ($this->database->exists('user', ['nickname' => $account['user']['nickname']])
-			|| $this->database->exists('userd', ['username' => $account['user']['nickname']])) {
+			|| $this->deletedUserRepository->existsByUsername($account['user']['nickname'])) {
 			$this->systemMessages->addNotice($this->t("User '%s' already exists on this server!", $account['user']['nickname']));
 			return;
 		}
diff --git a/src/Repository/CacheRepository.php b/src/Repository/CacheRepository.php
new file mode 100644
index 0000000000..6da86e7540
--- /dev/null
+++ b/src/Repository/CacheRepository.php
@@ -0,0 +1,40 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Repository;
+
+use Friendica\Database\DatabaseException;
+use Friendica\Entity\CacheEntity;
+
+/**
+ * Interface for a cache repository
+ */
+interface CacheRepository
+{
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return array<string>
+	 */
+	public function getAllKeysValidUntil(string $expires): array;
+
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return array<string>
+	 */
+	public function getAllKeysValidUntilWithPrefix(string $expires, string $prefix): array;
+
+	/**
+	 * @throws DatabaseException
+	 *
+	 * @return CacheEntity|null
+	 */
+	public function findOneByKeyValidUntil(string $key, string $expires);
+}
diff --git a/src/Repository/DeletedUserRepository.php b/src/Repository/DeletedUserRepository.php
new file mode 100644
index 0000000000..54b8a36fbc
--- /dev/null
+++ b/src/Repository/DeletedUserRepository.php
@@ -0,0 +1,33 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Repository;
+
+use Exception;
+use Friendica\Database\DatabaseException;
+
+/**
+ * Interface for a repository for deleted users
+ */
+interface DeletedUserRepository
+{
+	/**
+	 * Insert a deleted user by username.
+	 *
+	 * @throws DatabaseException If the username could not be inserted
+	 */
+	public function insertByUsername(string $username): void;
+
+	/**
+	 * Check if a deleted username exists.
+	 *
+	 * @throws \Exception
+	 */
+	public function existsByUsername(string $username): bool;
+}
diff --git a/tests/FixtureTestTrait.php b/tests/FixtureTestTrait.php
index 8c4508eeb8..e8ffd69b03 100644
--- a/tests/FixtureTestTrait.php
+++ b/tests/FixtureTestTrait.php
@@ -60,7 +60,7 @@ trait FixtureTestTrait
 
 		/** @var Database $dba */
 		$dba = $this->dice->create(Database::class);
-		$dba->setTestmode(true);
+		$dba->throwExceptionsOnErrors(true);
 
 		DBStructure::checkInitialValues();
 
diff --git a/tests/Unit/Database/Repository/CacheTableRepositoryTest.php b/tests/Unit/Database/Repository/CacheTableRepositoryTest.php
new file mode 100644
index 0000000000..cb710b2a59
--- /dev/null
+++ b/tests/Unit/Database/Repository/CacheTableRepositoryTest.php
@@ -0,0 +1,97 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Test\Unit\Database\Repository;
+
+use Friendica\Database\Database;
+use Friendica\Database\DatabaseException;
+use Friendica\Database\Repository\CacheTableRepository;
+use PHPUnit\Framework\TestCase;
+use Throwable;
+
+class CacheTableRepositoryTest extends TestCase
+{
+	public function testGetAllKeysValidUntilReturnsArray(): void
+	{
+		$stmt = new \stdClass;
+
+		$database = $this->createStub(Database::class);
+		$database->method('select')->willReturnMap([
+			['cache', ['k'], ['`expires` >= ?', '2025-04-16 10:12:01'], [], $stmt],
+		]);
+		$database->method('fetch')->willReturnOnConsecutiveCalls(
+			['k' => 'value1'],
+			['k' => 'value2'],
+			['k' => 'value3'],
+			false
+		);
+
+		$repo = new CacheTableRepository($database);
+
+		$this->assertSame(
+			[
+				'value1',
+				'value2',
+				'value3',
+			],
+			$repo->getAllKeysValidUntil('2025-04-16 10:12:01')
+		);
+	}
+
+	public function testGetAllKeysValidUntilThrowsException(): void
+	{
+		$database = $this->createStub(Database::class);
+		$database->method('select')->willThrowException($this->createStub(Throwable::class));
+
+		$repo = new CacheTableRepository($database);
+
+		$this->expectException(DatabaseException::class);
+
+		$repo->getAllKeysValidUntil('2025-04-16 10:12:01');
+	}
+
+	public function testGetAllKeysValidUntilWithPrefixReturnsArray(): void
+	{
+		$stmt = new \stdClass;
+
+		$database = $this->createStub(Database::class);
+		$database->method('select')->willReturnMap([
+			['cache', ['k'], ['`expires` >= ?', '2025-04-16 10:12:01'], [], $stmt],
+		]);
+		$database->method('fetch')->willReturnOnConsecutiveCalls(
+			['k' => 'value1'],
+			['k' => 'value2'],
+			['k' => 'value3'],
+			false
+		);
+
+		$repo = new CacheTableRepository($database);
+
+		$this->assertSame(
+			[
+				'value1',
+				'value2',
+				'value3',
+			],
+			$repo->getAllKeysValidUntilWithPrefix('2025-04-16 10:12:01', 'prefix')
+		);
+	}
+
+	public function testGetAllKeysValidUntilWithPrefixThrowsException(): void
+	{
+		$database = $this->createStub(Database::class);
+		$database->method('select')->willThrowException($this->createStub(Throwable::class));
+
+		$repo = new CacheTableRepository($database);
+
+		$this->expectException(DatabaseException::class);
+
+		$repo->getAllKeysValidUntilWithPrefix('2025-04-16 10:12:01', 'prefix');
+	}
+}
diff --git a/tests/Unit/Database/Repository/UserdTableRepositoryTest.php b/tests/Unit/Database/Repository/UserdTableRepositoryTest.php
new file mode 100644
index 0000000000..ff08ab5b5e
--- /dev/null
+++ b/tests/Unit/Database/Repository/UserdTableRepositoryTest.php
@@ -0,0 +1,77 @@
+<?php
+
+// Copyright (C) 2010-2024, the Friendica project
+// SPDX-FileCopyrightText: 2010-2024 the Friendica project
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace Friendica\Test\Unit\Database\Repository;
+
+use Friendica\Database\Database;
+use Friendica\Database\DatabaseException;
+use Friendica\Database\Repository\UserdTableRepository;
+use Friendica\Repository\DeletedUserRepository;
+use PHPUnit\Framework\TestCase;
+
+class UserdTableRepositoryTest extends TestCase
+{
+	public function testImplementationOfInterfaces(): void
+	{
+		$repo = new UserdTableRepository($this->createMock(Database::class));
+
+		$this->assertInstanceOf(DeletedUserRepository::class, $repo);
+	}
+
+	public function testInsertByUsernameCallsDatabase(): void
+	{
+		$database = $this->createMock(Database::class);
+		$database->expects($this->once())->method('insert')->willReturnMap([
+			['userd', ['username' => 'test'], 0, true],
+		]);
+
+		$repo = new UserdTableRepository($database);
+
+		$repo->insertByUsername('test');
+	}
+
+	public function testInsertByUsernameThrowsException(): void
+	{
+		$database = $this->createMock(Database::class);
+		$database->expects($this->exactly(2))->method('throwExceptionsOnErrors');
+		$database->expects($this->once())->method('insert')->willThrowException(
+			new DatabaseException('An error occured.', 0, 'SQL query')
+		);
+
+		$repo = new UserdTableRepository($database);
+
+		$this->expectException(DatabaseException::class);
+
+		$repo->insertByUsername('test');
+	}
+
+	public function testExistsByUsernameReturnsTrue(): void
+	{
+		$database = $this->createStub(Database::class);
+		$database->method('exists')->willReturnMap([
+			['userd', ['username' => 'test'], true],
+		]);
+
+		$repo = new UserdTableRepository($database);
+
+		$this->assertTrue($repo->existsByUsername('test'));
+	}
+
+	public function testExistsByUsernameReturnsFalse(): void
+	{
+		$database = $this->createStub(Database::class);
+		$database->method('exists')->willReturnMap([
+			['userd', ['username' => 'test'], false],
+		]);
+
+		$repo = new UserdTableRepository($database);
+
+		$this->assertFalse($repo->existsByUsername('test'));
+	}
+}
diff --git a/tests/Util/CreateDatabaseTrait.php b/tests/Util/CreateDatabaseTrait.php
index 05d3d6c0ca..c6ad09ef94 100644
--- a/tests/Util/CreateDatabaseTrait.php
+++ b/tests/Util/CreateDatabaseTrait.php
@@ -43,7 +43,7 @@ trait CreateDatabaseTrait
 		]));
 
 		$database = new StaticDatabase($config, (new DbaDefinition($this->root->url()))->load(), (new ViewDefinition($this->root->url()))->load());
-		$database->setTestmode(true);
+		$database->throwExceptionsOnErrors(true);
 
 		return $database;
 	}