diff --git a/test/Double/Holidays/Calendar/HolidayApiWrapperMock.php b/test/Double/Holidays/Calendar/HolidayApiWrapperMock.php
index a4a7bfb..c219bac 100644
--- a/test/Double/Holidays/Calendar/HolidayApiWrapperMock.php
+++ b/test/Double/Holidays/Calendar/HolidayApiWrapperMock.php
@@ -4,7 +4,7 @@
 
 use HolidayAPI\Client;
 
-class HolidayApiWrapperMock extends Client
+final class HolidayApiWrapperMock extends Client
 {
     private bool $isFailing = false;
 
diff --git a/test/Double/Holidays/Calendar/HolidaysCalendarMock.php b/test/Double/Holidays/Calendar/HolidaysCalendarMock.php
index bdb5b88..7b1bdf3 100644
--- a/test/Double/Holidays/Calendar/HolidaysCalendarMock.php
+++ b/test/Double/Holidays/Calendar/HolidaysCalendarMock.php
@@ -4,7 +4,7 @@
 
 use Nati\Businesscal\Holidays\HolidaysCalendar;
 
-class HolidaysCalendarMock implements HolidaysCalendar
+final class HolidaysCalendarMock implements HolidaysCalendar
 {
     private array $holidays = [];
 
diff --git a/test/Integration/HolidayApiFRBusinessCalendarTest.php b/test/Integration/HolidayApiFRBusinessCalendarTest.php
index 6be9d9d..8220b80 100644
--- a/test/Integration/HolidayApiFRBusinessCalendarTest.php
+++ b/test/Integration/HolidayApiFRBusinessCalendarTest.php
@@ -7,7 +7,7 @@
 use Nati\Businesscal\Holidays\Calendar\HolidayApiCalendar;
 use PHPUnit\Framework\Attributes\Test;
 
-class HolidayApiFRBusinessCalendarTest extends FRBusinessCalendar
+final class HolidayApiFRBusinessCalendarTest extends FRBusinessCalendar
 {
     private string $apiKey = '150cc546-b50d-4afc-b681-d2f8d3963239';
 
diff --git a/test/Integration/StaticFRBusinessCalendarTest.php b/test/Integration/StaticFRBusinessCalendarTest.php
index 32471ee..5c93d4b 100644
--- a/test/Integration/StaticFRBusinessCalendarTest.php
+++ b/test/Integration/StaticFRBusinessCalendarTest.php
@@ -6,7 +6,7 @@
 use Nati\Businesscal\Holidays\Calendar\FRHolidaysCalendar;
 use PHPUnit\Framework\Attributes\Test;
 
-class StaticFRBusinessCalendarTest extends FRBusinessCalendar
+final class StaticFRBusinessCalendarTest extends FRBusinessCalendar
 {
     #[Test]
     public function canAddManyDays()
diff --git a/test/Unit/BusinessCalendarTest.php b/test/Unit/BusinessCalendarTest.php
index fbacb58..887e011 100644
--- a/test/Unit/BusinessCalendarTest.php
+++ b/test/Unit/BusinessCalendarTest.php
@@ -8,7 +8,7 @@
 use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 
-class BusinessCalendarTest extends TestCase
+final class BusinessCalendarTest extends TestCase
 {
     private readonly HolidaysCalendarMock $holidays;
 
diff --git a/test/Unit/Holidays/Calendar/CHNationalPredictableHolidaysCalendarTest.php b/test/Unit/Holidays/Calendar/CHNationalPredictableHolidaysCalendarTest.php
index d7eb9b8..35e5e5a 100644
--- a/test/Unit/Holidays/Calendar/CHNationalPredictableHolidaysCalendarTest.php
+++ b/test/Unit/Holidays/Calendar/CHNationalPredictableHolidaysCalendarTest.php
@@ -5,7 +5,7 @@
 use Nati\Businesscal\Holidays\Calendar\CHNationalHolidaysCalendar;
 use Nati\Businesscal\Holidays\HolidaysCalendar;
 
-class CHNationalPredictableHolidaysCalendarTest extends PredictableHolidaysCalendar
+final class CHNationalPredictableHolidaysCalendarTest extends PredictableHolidaysCalendar
 {
     public static function expected2017Holidays(): array
     {
diff --git a/test/Unit/Holidays/Calendar/FRPredictableHolidaysCalendarTest.php b/test/Unit/Holidays/Calendar/FRPredictableHolidaysCalendarTest.php
index 373350f..5de879f 100644
--- a/test/Unit/Holidays/Calendar/FRPredictableHolidaysCalendarTest.php
+++ b/test/Unit/Holidays/Calendar/FRPredictableHolidaysCalendarTest.php
@@ -5,7 +5,7 @@
 use Nati\Businesscal\Holidays\Calendar\FRHolidaysCalendar;
 use Nati\Businesscal\Holidays\HolidaysCalendar;
 
-class FRPredictableHolidaysCalendarTest extends PredictableHolidaysCalendar
+final class FRPredictableHolidaysCalendarTest extends PredictableHolidaysCalendar
 {
     public static function expected2017Holidays(): array
     {
diff --git a/test/Unit/Holidays/Calendar/PFHolidaysCalendarTest.php b/test/Unit/Holidays/Calendar/PFHolidaysCalendarTest.php
index 5a7a791..df4b22e 100644
--- a/test/Unit/Holidays/Calendar/PFHolidaysCalendarTest.php
+++ b/test/Unit/Holidays/Calendar/PFHolidaysCalendarTest.php
@@ -5,7 +5,7 @@
 use Nati\Businesscal\Holidays\Calendar\PFHolidaysCalendar;
 use Nati\Businesscal\Holidays\HolidaysCalendar;
 
-class PFHolidaysCalendarTest extends PredictableHolidaysCalendar
+final class PFHolidaysCalendarTest extends PredictableHolidaysCalendar
 {
     public static function expected2017Holidays(): array
     {
diff --git a/test/Unit/Holidays/Calendar/SolidarityFRHolidaysCalendarTest.php b/test/Unit/Holidays/Calendar/SolidarityFRHolidaysCalendarTest.php
index 1970459..a5a4f91 100644
--- a/test/Unit/Holidays/Calendar/SolidarityFRHolidaysCalendarTest.php
+++ b/test/Unit/Holidays/Calendar/SolidarityFRHolidaysCalendarTest.php
@@ -5,7 +5,7 @@
 use Nati\Businesscal\Holidays\Calendar\SolidarityFRHolidaysCalendar;
 use Nati\Businesscal\Holidays\HolidaysCalendar;
 
-class SolidarityFRHolidaysCalendarTest extends PredictableHolidaysCalendar
+final class SolidarityFRHolidaysCalendarTest extends PredictableHolidaysCalendar
 {
     public static function expected2017Holidays(): array
     {