diff --git a/.github/workflows/format_php.yml b/.github/workflows/format_php.yml
index 6b91144..0ef2144 100644
--- a/.github/workflows/format_php.yml
+++ b/.github/workflows/format_php.yml
@@ -13,9 +13,6 @@ jobs:
       with:
         ref: ${{ github.head_ref }}
 
-    - name: Install
-      run: composer install
-
     - name: Run php-cs-fixer
       uses: docker://oskarstark/php-cs-fixer-ga
 
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index e6cd19a..de969b8 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,7 +9,7 @@ jobs:
       fail-fast: true
       matrix:
         os: [ubuntu-latest]
-        php: [7.4, 8.0, 8.1, 8.2]
+        php: [8.2]
         stability: [prefer-lowest, prefer-stable]
 
     name: P${{ matrix.php }} - ${{ matrix.stability }} - ${{ matrix.os }}
diff --git a/README.md b/README.md
index 74bc1ee..6a6033b 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ Using Javascript? Check out [@stefanzweifel/js-swiss-cantons](https://github.com
 
 ## Installation
 
-The easiest way to install the package is by using composer. The package requires PHP 7.4.
+The easiest way to install the package is by using composer. The package requires PHP 8.2.
 
 ```shell
 composer require "wnx/php-swiss-cantons"
diff --git a/composer.json b/composer.json
index b4cf0e0..e231e29 100644
--- a/composer.json
+++ b/composer.json
@@ -17,15 +17,15 @@
         }
     ],
     "require": {
-        "php": ">=7.4.0 || ^8.0",
+        "php": "^8.2",
         "ext-json": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9 | ^10",
+        "phpunit/phpunit": "^10.1",
         "friendsofphp/php-cs-fixer": "^3",
         "vimeo/psalm": "^5.0",
         "league/csv": "^9.7",
-        "symfony/console": "^5.0 | ^6.0",
+        "symfony/console": "^6.0",
         "rector/rector": "^0.15.24"
     },
     "autoload": {
diff --git a/rector.php b/rector.php
index 4ed828c..34a1608 100644
--- a/rector.php
+++ b/rector.php
@@ -4,6 +4,7 @@
 
 use Rector\CodeQuality\Rector\Class_\InlineConstructorDefaultToPropertyRector;
 use Rector\Config\RectorConfig;
+use Rector\PHPUnit\Set\PHPUnitSetList;
 use Rector\Set\ValueObject\LevelSetList;
 
 return static function (RectorConfig $rectorConfig): void {
@@ -17,6 +18,7 @@
 
     // define sets of rules
     $rectorConfig->sets([
-     LevelSetList::UP_TO_PHP_74
- ]);
+        LevelSetList::UP_TO_PHP_82,
+        PHPUnitSetList::PHPUNIT_100,
+    ]);
 };
diff --git a/src/Canton.php b/src/Canton.php
index 7e48e22..8413da7 100644
--- a/src/Canton.php
+++ b/src/Canton.php
@@ -6,17 +6,17 @@
 
 class Canton
 {
-    public const LANG_GERMAN = 'de';
+    final public const LANG_GERMAN = 'de';
 
-    public const LANG_FRENCH = 'fr';
+    final public const LANG_FRENCH = 'fr';
 
-    public const LANG_ITALIAN = 'it';
+    final public const LANG_ITALIAN = 'it';
 
-    public const LANG_ENGLISH = 'en';
+    final public const LANG_ENGLISH = 'en';
 
-    public const LANG_ROMANSH = 'rm';
+    final public const LANG_ROMANSH = 'rm';
 
-    public const AVAILABLE_LANGUAGES = [
+    final public const AVAILABLE_LANGUAGES = [
         self::LANG_GERMAN,
         self::LANG_FRENCH,
         self::LANG_ITALIAN,
diff --git a/src/CantonSearch.php b/src/CantonSearch.php
index 41284c2..2d8601a 100644
--- a/src/CantonSearch.php
+++ b/src/CantonSearch.php
@@ -13,9 +13,7 @@ public function __construct()
 
     public function findByAbbreviation(string $abbreviation): ?Canton
     {
-        $result = array_filter($this->dataSet, function (Canton $canton) use ($abbreviation) {
-            return $canton->getAbbreviation() === strtoupper($abbreviation);
-        });
+        $result = array_filter($this->dataSet, fn (Canton $canton) => $canton->getAbbreviation() === strtoupper($abbreviation));
 
         if (count($result) === 0) {
             return null;
@@ -26,9 +24,7 @@ public function findByAbbreviation(string $abbreviation): ?Canton
 
     public function findByName(string $name): ?Canton
     {
-        $result = array_filter($this->dataSet, function (Canton $canton) use ($name) {
-            return in_array($name, $canton->getNamesArray());
-        });
+        $result = array_filter($this->dataSet, fn (Canton $canton) => in_array($name, $canton->getNamesArray()));
 
         if (count($result) === 0) {
             return null;
diff --git a/src/Cantons.php b/src/Cantons.php
index abe2db1..ebe5293 100644
--- a/src/Cantons.php
+++ b/src/Cantons.php
@@ -8,7 +8,7 @@ class Cantons
 
     public function __construct()
     {
-        $this->cantons = json_decode(file_get_contents(__DIR__.'/data/cantons.json'), true);
+        $this->cantons = json_decode(file_get_contents(__DIR__.'/data/cantons.json'), true, 512, JSON_THROW_ON_ERROR);
     }
 
     /**
@@ -18,9 +18,7 @@ public function __construct()
      */
     public function getAll(): array
     {
-        return array_map(function ($canton) {
-            return new Canton($canton);
-        }, $this->cantons);
+        return array_map(fn ($canton) => new Canton($canton), $this->cantons);
     }
 
     /**
diff --git a/src/Console/UpdateZipcodeDatasetCommand.php b/src/Console/UpdateZipcodeDatasetCommand.php
index d7b04d4..f7e59fd 100644
--- a/src/Console/UpdateZipcodeDatasetCommand.php
+++ b/src/Console/UpdateZipcodeDatasetCommand.php
@@ -13,8 +13,8 @@
 
 class UpdateZipcodeDatasetCommand extends Command
 {
-    public const PATH_TO_CSV = __DIR__ . '/../data/zipcodes.csv';
-    public const PATH_TO_JSON = __DIR__ . '/../data/zipcodes.json';
+    final public const PATH_TO_CSV = __DIR__ . '/../data/zipcodes.csv';
+    final public const PATH_TO_JSON = __DIR__ . '/../data/zipcodes.json';
 
     protected function configure(): void
     {
diff --git a/src/ZipcodeSearch.php b/src/ZipcodeSearch.php
index a482d04..ed750b8 100644
--- a/src/ZipcodeSearch.php
+++ b/src/ZipcodeSearch.php
@@ -16,9 +16,7 @@ public function __construct()
      */
     public function findbyZipcode(int $zipcode): ?array
     {
-        $result = array_filter($this->dataSet, function (array $city) use ($zipcode) {
-            return $city['zipcode'] === intval($zipcode);
-        });
+        $result = array_filter($this->dataSet, fn (array $city) => $city['zipcode'] === intval($zipcode));
 
         if (count($result) === 0) {
             return null;
@@ -29,6 +27,6 @@ public function findbyZipcode(int $zipcode): ?array
 
     public function getDataSet(): array
     {
-        return json_decode(file_get_contents(__DIR__.'/data/zipcodes.json'), true);
+        return json_decode(file_get_contents(__DIR__.'/data/zipcodes.json'), true, 512, JSON_THROW_ON_ERROR);
     }
 }
diff --git a/tests/CantonManagerTest.php b/tests/CantonManagerTest.php
index 10a72e8..a7bb825 100644
--- a/tests/CantonManagerTest.php
+++ b/tests/CantonManagerTest.php
@@ -2,13 +2,14 @@
 
 namespace Wnx\SwissCantons\Tests;
 
+use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 use Wnx\SwissCantons\CantonManager;
 use Wnx\SwissCantons\Exceptions\CantonException;
 
 class CantonManagerTest extends TestCase
 {
-    /** @test */
+    #[Test]
     public function it_returns_correct_canton_instance_for_abbreviation()
     {
         $canton = new CantonManager();
@@ -20,7 +21,7 @@ public function it_returns_correct_canton_instance_for_abbreviation()
         );
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_correct_canton_if_abbreviation_is_lowercase()
     {
         $cantonManager = new CantonManager();
@@ -44,7 +45,7 @@ public function it_returns_correct_canton_if_abbreviation_is_lowercase()
         );
     }
 
-    /** @test */
+    #[Test]
     public function it_throws_exception_if_no_canton_for_abbreviation_is_found()
     {
         $this->expectException(CantonException::class);
@@ -53,7 +54,7 @@ public function it_throws_exception_if_no_canton_for_abbreviation_is_found()
         $result = $canton->getByAbbreviation('FOO');
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_correct_canton_instance_for_name()
     {
         $canton = new CantonManager();
@@ -62,7 +63,7 @@ public function it_returns_correct_canton_instance_for_name()
         $this->assertEquals('ZH', $result->getAbbreviation());
     }
 
-    /** @test */
+    #[Test]
     public function it_throws_exception_if_not_canton_for_name_is_found()
     {
         $this->expectException(CantonException::class);
@@ -71,7 +72,7 @@ public function it_throws_exception_if_not_canton_for_name_is_found()
         $result = $canton->getByName('FOO');
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_canton_for_zipcode()
     {
         $canton = new CantonManager();
@@ -82,7 +83,7 @@ public function it_returns_canton_for_zipcode()
         $this->assertEquals('Berne', $result->setLanguage('en')->getName());
     }
 
-    /** @test */
+    #[Test]
     public function it_throws_exception_if_no_canton_for_zipcode_could_be_found()
     {
         $this->expectException(CantonException::class);
@@ -91,7 +92,7 @@ public function it_throws_exception_if_no_canton_for_zipcode_could_be_found()
         $result = $canton->getByZipcode(9999);
     }
 
-    /** @test */
+    #[Test]
     public function it_throws_exception_if_lichtenstein_zipcode_is_searched_for()
     {
         $this->expectException(CantonException::class);
diff --git a/tests/CantonSearchTest.php b/tests/CantonSearchTest.php
index 79d13a3..b09476d 100644
--- a/tests/CantonSearchTest.php
+++ b/tests/CantonSearchTest.php
@@ -2,13 +2,14 @@
 
 namespace Wnx\SwissCantons\Tests;
 
+use PHPUnit\Framework\Attributes\Test;
 use Wnx\SwissCantons\Canton;
 use PHPUnit\Framework\TestCase;
 use Wnx\SwissCantons\CantonSearch;
 
 class CantonSearchTest extends TestCase
 {
-    /** @test */
+    #[Test]
     public function it_finds_canton_by_abbreviation()
     {
         $cantonSearch = new CantonSearch();
@@ -18,7 +19,7 @@ public function it_finds_canton_by_abbreviation()
         $this->assertEquals('SH', $canton->getAbbreviation());
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_null_if_no_canton_for_abbreviation_was_found()
     {
         $cantonSearch = new CantonSearch();
@@ -27,7 +28,7 @@ public function it_returns_null_if_no_canton_for_abbreviation_was_found()
         $this->assertNull($canton);
     }
 
-    /** @test */
+    #[Test]
     public function it_finds_canton_by_name()
     {
         $cantonSearch = new CantonSearch();
@@ -38,7 +39,7 @@ public function it_finds_canton_by_name()
         $this->assertEquals('Zürich', $canton->getNamesArray()['de']);
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_null_if_no_canton_for_name_was_found()
     {
         $cantonSearch = new CantonSearch();
diff --git a/tests/CantonTest.php b/tests/CantonTest.php
index abe5196..c68d167 100644
--- a/tests/CantonTest.php
+++ b/tests/CantonTest.php
@@ -2,6 +2,7 @@
 
 namespace Wnx\SwissCantons\Tests;
 
+use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 use Wnx\SwissCantons\Canton;
 use Wnx\SwissCantons\Exceptions\InvalidLanguageException;
@@ -22,7 +23,7 @@ protected function getExampleCanton(): array
         ];
     }
 
-    /** @test */
+    #[Test]
     public function it_sets_language()
     {
         $canton = new Canton($this->getExampleCanton());
@@ -31,7 +32,7 @@ public function it_sets_language()
         $this->assertEquals('fr', $canton->getLanguage());
     }
 
-    /** @test */
+    #[Test]
     public function it_transformers_uppercase_language_string_to_lowercase()
     {
         $canton = new Canton($this->getExampleCanton());
@@ -40,7 +41,7 @@ public function it_transformers_uppercase_language_string_to_lowercase()
         $this->assertEquals('de', $canton->getLanguage());
     }
 
-    /** @test */
+    #[Test]
     public function it_only_allows_national_languages()
     {
         $this->expectException(InvalidLanguageException::class);
@@ -49,7 +50,7 @@ public function it_only_allows_national_languages()
         $canton->setLanguage('es');
     }
 
-    /** @test */
+    #[Test]
     public function it_sets_and_returns_abbreviation()
     {
         $canton = new Canton($this->getExampleCanton());
@@ -57,7 +58,7 @@ public function it_sets_and_returns_abbreviation()
         $this->assertEquals('ZH', $canton->getAbbreviation());
     }
 
-    /** @test */
+    #[Test]
     public function it_sets_names_array()
     {
         $canton = new Canton($this->getExampleCanton());
@@ -68,7 +69,7 @@ public function it_sets_names_array()
         );
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_correct_name_for_given_language()
     {
         $canton = new Canton($this->getExampleCanton());
diff --git a/tests/CantonsTest.php b/tests/CantonsTest.php
index b5358e7..96016e5 100644
--- a/tests/CantonsTest.php
+++ b/tests/CantonsTest.php
@@ -3,12 +3,13 @@
 namespace Wnx\SwissCantons\Tests;
 
 use Exception;
+use PHPUnit\Framework\Attributes\Test;
 use Wnx\SwissCantons\Cantons;
 use PHPUnit\Framework\TestCase;
 
 class CantonsTest extends TestCase
 {
-    /** @test */
+    #[Test]
     public function it_returns_json_source_as_array()
     {
         $cantons = new Cantons();
@@ -16,7 +17,7 @@ public function it_returns_json_source_as_array()
         $this->assertTrue(is_array($cantons->getAll()));
     }
 
-    /** @test */
+    #[Test]
     public function it_contains_abbreviation_and_name()
     {
         $cantons = (new Cantons())->getAll();
@@ -29,7 +30,7 @@ public function it_contains_abbreviation_and_name()
         $this->assertArrayHasKey('en', $cantons[0]->getNamesArray());
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_an_array_with_abbreviation_as_key_and_name_as_value()
     {
         $cantons = (new Cantons())->getAllAsArray();
@@ -41,7 +42,7 @@ public function it_returns_an_array_with_abbreviation_as_key_and_name_as_value()
         $this->assertEquals('Zurich', $cantons['ZH']);
     }
 
-    /** @test */
+    #[Test]
     public function it_returns_an_array_with_abbreviation_and_name_but_in_a_different_language()
     {
         $cantons = (new Cantons())->getAllAsArray('de');
@@ -53,7 +54,7 @@ public function it_returns_an_array_with_abbreviation_and_name_but_in_a_differen
         $this->assertEquals('Zürich', $cantons['ZH']);
     }
 
-    /** @test */
+    #[Test]
     public function it_throws_an_exception_if_passed_langauge_is_not_available()
     {
         $this->expectException(Exception::class);
diff --git a/tests/ZipcodeSearchTest.php b/tests/ZipcodeSearchTest.php
index f974153..0413e6d 100644
--- a/tests/ZipcodeSearchTest.php
+++ b/tests/ZipcodeSearchTest.php
@@ -2,12 +2,13 @@
 
 namespace Wnx\SwissCantons\Tests;
 
+use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 use Wnx\SwissCantons\ZipcodeSearch;
 
 class ZipcodeSearchTest extends TestCase
 {
-    /** @test */
+    #[Test]
     public function it_returns_dataset_as_array()
     {
         $cantonSearch = new ZipcodeSearch();
@@ -15,7 +16,7 @@ public function it_returns_dataset_as_array()
         $this->assertIsArray($cantonSearch->getDataSet());
     }
 
-    /** @test */
+    #[Test]
     public function it_finds_canton_by_zipcode()
     {
         $zipcodeSearch = new ZipcodeSearch();
@@ -27,7 +28,7 @@ public function it_finds_canton_by_zipcode()
         $this->assertEquals('Bern', $result['city']);
     }
 
-    /** @test */
+    #[Test]
     public function it_does_not_find_result_for_not_available_zipcode()
     {
         $zipcodeSearch = new ZipcodeSearch();
@@ -37,7 +38,7 @@ public function it_does_not_find_result_for_not_available_zipcode()
         $this->assertEquals(null, $result);
     }
 
-    /** @test */
+    #[Test]
     public function it_does_not_find_liechtenstein_zipcodes()
     {
         $zipcodeSearch = new ZipcodeSearch();