diff --git a/api/rector.php b/api/rector.php
index 3f72e3e576..4089220aef 100644
--- a/api/rector.php
+++ b/api/rector.php
@@ -19,6 +19,7 @@
 use Rector\PHPUnit\CodeQuality\Rector\Class_\PreferPHPUnitThisCallRector;
 use Rector\PHPUnit\CodeQuality\Rector\ClassMethod\AddInstanceofAssertForNullableInstanceRector;
 use Rector\PHPUnit\CodeQuality\Rector\MethodCall\AssertEmptyNullableObjectToAssertInstanceofRector;
+use Rector\PHPUnit\CodeQuality\Rector\StmtsAwareInterface\DeclareStrictTypesTestsRector;
 use Rector\Privatization\Rector\Class_\FinalizeTestCaseClassRector;
 use Rector\Renaming\Rector\FuncCall\RenameFunctionRector;
 use Rector\Strict\Rector\Empty_\DisallowedEmptyRuleFixerRector;
@@ -50,6 +51,7 @@
         CombineIfRector::class,
         ConstraintOptionsToNamedArgumentsRector::class,
         DeclareStrictTypesRector::class,
+        DeclareStrictTypesTestsRector::class,
         DisallowedEmptyRuleFixerRector::class,
         ExplicitBoolCompareRector::class,
         FinalizeTestCaseClassRector::class,
diff --git a/api/src/Controller/CevidbController.php b/api/src/Controller/CevidbController.php
index 69c0a3ce0e..f2653a4c6d 100644
--- a/api/src/Controller/CevidbController.php
+++ b/api/src/Controller/CevidbController.php
@@ -8,12 +8,14 @@
 use Symfony\Component\Routing\Annotation\Route;
 
 class CevidbController extends AbstractController {
+    public function __construct(private readonly ClientRegistry $clientRegistry) {}
+
     /**
      * Link to this controller to start the "connect" process.
      */
     #[Route('/auth/cevidb', name: 'connect_cevidb_start')]
-    public function connect(Request $request, ClientRegistry $clientRegistry) {
-        return $clientRegistry
+    public function connect(Request $request) {
+        return $this->clientRegistry
             ->getClient('cevidb') // key used in config/packages/knpu_oauth2_client.yaml
             ->redirect([], ['additionalData' => ['callback' => $request->get('callback')]])
         ;
@@ -25,7 +27,7 @@ public function connect(Request $request, ClientRegistry $clientRegistry) {
      * in config/packages/knpu_oauth2_client.yaml.
      */
     #[Route('/auth/cevidb/callback', name: 'connect_cevidb_check')]
-    public function connectCheck(ClientRegistry $clientRegistry) {
+    public function connectCheck() {
         // ** if you want to *authenticate* the user, then
         // leave this method blank and create a custom authenticator
     }
diff --git a/api/src/Controller/GoogleController.php b/api/src/Controller/GoogleController.php
index 17a96b8199..93229d3442 100644
--- a/api/src/Controller/GoogleController.php
+++ b/api/src/Controller/GoogleController.php
@@ -8,12 +8,14 @@
 use Symfony\Component\Routing\Annotation\Route;
 
 class GoogleController extends AbstractController {
+    public function __construct(private readonly ClientRegistry $clientRegistry) {}
+
     /**
      * Link to this controller to start the "connect" process.
      */
     #[Route('/auth/google', name: 'connect_google_start')]
-    public function connect(Request $request, ClientRegistry $clientRegistry) {
-        return $clientRegistry
+    public function connect(Request $request) {
+        return $this->clientRegistry
             ->getClient('google') // key used in config/packages/knpu_oauth2_client.yaml
             ->redirect([], ['additionalData' => ['callback' => $request->get('callback')]])
         ;
@@ -25,7 +27,7 @@ public function connect(Request $request, ClientRegistry $clientRegistry) {
      * in config/packages/knpu_oauth2_client.yaml.
      */
     #[Route('/auth/google/callback', name: 'connect_google_check')]
-    public function connectCheck(ClientRegistry $clientRegistry) {
+    public function connectCheck() {
         // ** if you want to *authenticate* the user, then
         // leave this method blank and create a custom authenticator
     }
diff --git a/api/src/Controller/JubladbController.php b/api/src/Controller/JubladbController.php
index 2a5800340d..ee21b626b8 100644
--- a/api/src/Controller/JubladbController.php
+++ b/api/src/Controller/JubladbController.php
@@ -8,12 +8,14 @@
 use Symfony\Component\Routing\Annotation\Route;
 
 class JubladbController extends AbstractController {
+    public function __construct(private readonly ClientRegistry $clientRegistry) {}
+
     /**
      * Link to this controller to start the "connect" process.
      */
     #[Route('/auth/jubladb', name: 'connect_jubladb_start')]
-    public function connect(Request $request, ClientRegistry $clientRegistry) {
-        return $clientRegistry
+    public function connect(Request $request) {
+        return $this->clientRegistry
             ->getClient('jubladb') // key used in config/packages/knpu_oauth2_client.yaml
             ->redirect([], ['additionalData' => ['callback' => $request->get('callback')]])
         ;
@@ -25,7 +27,7 @@ public function connect(Request $request, ClientRegistry $clientRegistry) {
      * in config/packages/knpu_oauth2_client.yaml.
      */
     #[Route('/auth/jubladb/callback', name: 'connect_jubladb_check')]
-    public function connectCheck(ClientRegistry $clientRegistry) {
+    public function connectCheck() {
         // ** if you want to *authenticate* the user, then
         // leave this method blank and create a custom authenticator
     }
diff --git a/api/src/Controller/PbsmidataController.php b/api/src/Controller/PbsmidataController.php
index 6a5d35ede3..bdc3926f68 100644
--- a/api/src/Controller/PbsmidataController.php
+++ b/api/src/Controller/PbsmidataController.php
@@ -8,12 +8,14 @@
 use Symfony\Component\Routing\Annotation\Route;
 
 class PbsmidataController extends AbstractController {
+    public function __construct(private readonly ClientRegistry $clientRegistry) {}
+
     /**
      * Link to this controller to start the "connect" process.
      */
     #[Route('/auth/pbsmidata', name: 'connect_pbsmidata_start')]
-    public function connect(Request $request, ClientRegistry $clientRegistry) {
-        return $clientRegistry
+    public function connect(Request $request) {
+        return $this->clientRegistry
             ->getClient('pbsmidata') // key used in config/packages/knpu_oauth2_client.yaml
             ->redirect([], ['additionalData' => ['callback' => $request->get('callback')]])
         ;
@@ -25,7 +27,7 @@ public function connect(Request $request, ClientRegistry $clientRegistry) {
      * in config/packages/knpu_oauth2_client.yaml.
      */
     #[Route('/auth/pbsmidata/callback', name: 'connect_pbsmidata_check')]
-    public function connectCheck(ClientRegistry $clientRegistry) {
+    public function connectCheck() {
         // ** if you want to *authenticate* the user, then
         // leave this method blank and create a custom authenticator
     }
diff --git a/api/tests/Doctrine/Filter/ExpressionDateTimeFilterTest.php b/api/tests/Doctrine/Filter/ExpressionDateTimeFilterTest.php
index 1dabdd9100..6ba12c5b20 100644
--- a/api/tests/Doctrine/Filter/ExpressionDateTimeFilterTest.php
+++ b/api/tests/Doctrine/Filter/ExpressionDateTimeFilterTest.php
@@ -56,7 +56,7 @@ public function setUp(): void {
 
     public function testGetDescriptionDoesNothingWhenNoPropertiesDefined() {
         // given
-        $filter = new ExpressionDateTimeFilter($this->managerRegistryMock, null, null);
+        $filter = new ExpressionDateTimeFilter($this->managerRegistryMock);
 
         // when
         $description = $filter->getDescription('Dummy');
diff --git a/api/tests/OAuth/JWTStateOAuth2ClientTest.php b/api/tests/OAuth/JWTStateOAuth2ClientTest.php
index 94c4c9f47e..5f9134a539 100644
--- a/api/tests/OAuth/JWTStateOAuth2ClientTest.php
+++ b/api/tests/OAuth/JWTStateOAuth2ClientTest.php
@@ -106,9 +106,7 @@ public function testRedirectPersistsStateToTheDatabase() {
         // then
         $entityManagerMock->expects($this->once())
             ->method('persist')
-            ->with($this->callback(function ($value) {
-                return $value instanceof OAuthState;
-            }))
+            ->with($this->isInstanceOf(OAuthState::class))
         ;
         // Should also clean up the database table
         $repositoryMock->expects($this->once())->method('deleteAllExpiredBefore');
diff --git a/api/tests/Service/MailServiceTest.php b/api/tests/Service/MailServiceTest.php
index b1f48b26f2..3c5a373ec9 100644
--- a/api/tests/Service/MailServiceTest.php
+++ b/api/tests/Service/MailServiceTest.php
@@ -24,7 +24,6 @@ class MailServiceTest extends KernelTestCase {
 
     private Camp $camp;
     private User $user;
-    private Security $security;
 
     private MailService $mailer;
 
@@ -35,15 +34,15 @@ protected function setUp(): void {
         $translator = self::getContainer()->get(TranslatorInterface::class);
         $twigEnvironment = self::getContainer()->get(Environment::class);
 
-        $this->security = $this->createMock(Security::class);
+        $security = $this->createMock(Security::class);
         $profile = new Profile();
         $profile->nickname = 'Linux';
         $profile->email = 'sender@ecamp3.ch';
         $user = new User();
         $user->profile = $profile;
-        $this->security->method('getUser')->willReturn($user);
+        $security->method('getUser')->willReturn($user);
 
-        $this->mailer = new MailService($mailer, $translator, $twigEnvironment, 'frontend.example.com', 'sender@example.com', 'SenderName', $this->security);
+        $this->mailer = new MailService($mailer, $translator, $twigEnvironment, 'frontend.example.com', 'sender@example.com', 'SenderName', $security);
 
         $this->user = new User();
         $profile = new Profile();