diff --git a/tests/Bootloader/SerializerBootloaderTest.php b/tests/Bootloader/SerializerBootloaderTest.php
index 70cf8c2..903f436 100644
--- a/tests/Bootloader/SerializerBootloaderTest.php
+++ b/tests/Bootloader/SerializerBootloaderTest.php
@@ -34,9 +34,9 @@ public function testDefaultSerializerIsConfigured(): void
         ]);
 
         $manager = $this->container->get(SerializerManager::class);
-        $this->assertInstanceOf(SerializerManager::class, $manager);
-        $this->assertInstanceOf(PhpSerializer::class, $manager->getSerializer('serializer'));
-        $this->assertInstanceOf(JsonSerializer::class, $manager->getSerializer('json'));
+        self::assertInstanceOf(SerializerManager::class, $manager);
+        self::assertInstanceOf(PhpSerializer::class, $manager->getSerializer('serializer'));
+        self::assertInstanceOf(JsonSerializer::class, $manager->getSerializer('json'));
 
         $this->expectException(SerializerNotFoundException::class);
         $manager->getSerializer('foo');
@@ -50,8 +50,8 @@ public function testAddSerializer(): void
         $registry->register('callback', new CallbackSerializer(fn () => null, fn () => null));
 
         $manager = $this->container->get(SerializerManager::class);
-        $this->assertInstanceOf(SerializerManager::class, $manager);
-        $this->assertInstanceOf(CallbackSerializer::class, $manager->getSerializer('callback'));
+        self::assertInstanceOf(SerializerManager::class, $manager);
+        self::assertInstanceOf(CallbackSerializer::class, $manager->getSerializer('callback'));
 
         $this->expectException(SerializerNotFoundException::class);
         $manager->getSerializer('foo');
@@ -64,7 +64,7 @@ public function testAddSerializerByClassString(): void
         $this->configureSerializer(['json' => PhpSerializer::class]);
 
         $manager = $this->container->get(SerializerManager::class);
-        $this->assertInstanceOf(PhpSerializer::class, $manager->getSerializer('json'));
+        self::assertInstanceOf(PhpSerializer::class, $manager->getSerializer('json'));
     }
 
     public function testAddSerializerByAutowire(): void
@@ -72,7 +72,7 @@ public function testAddSerializerByAutowire(): void
         $this->configureSerializer(['json' => new Autowire(PhpSerializer::class)]);
 
         $manager = $this->container->get(SerializerManager::class);
-        $this->assertInstanceOf(PhpSerializer::class, $manager->getSerializer('json'));
+        self::assertInstanceOf(PhpSerializer::class, $manager->getSerializer('json'));
     }
 
     private function configureSerializer(array $serializers = []): void
diff --git a/tests/Serializer/CallbackSerializerTest.php b/tests/Serializer/CallbackSerializerTest.php
index b2c7ad6..6fed90f 100644
--- a/tests/Serializer/CallbackSerializerTest.php
+++ b/tests/Serializer/CallbackSerializerTest.php
@@ -16,7 +16,7 @@ public function testSerializer(): void
             static fn (mixed $payload): mixed => $payload
         );
 
-        $this->assertSame('serialize', $serializer->serialize('serialize'));
-        $this->assertSame('unserialize', $serializer->unserialize('unserialize'));
+        self::assertSame('serialize', $serializer->serialize('serialize'));
+        self::assertSame('unserialize', $serializer->unserialize('unserialize'));
     }
 }
diff --git a/tests/Serializer/JsonSerializerTest.php b/tests/Serializer/JsonSerializerTest.php
index 59b09b9..80f5be4 100644
--- a/tests/Serializer/JsonSerializerTest.php
+++ b/tests/Serializer/JsonSerializerTest.php
@@ -15,9 +15,9 @@ public function testSerializer(): void
     {
         $serializer = new JsonSerializer();
 
-        $this->assertSame('["some","elements"]', $serializer->serialize(['some', 'elements']));
-        $this->assertSame(['some', 'elements'], $serializer->unserialize('["some","elements"]'));
-        $this->assertSame(['some', 'elements'], $serializer->unserialize(new class() implements \Stringable {
+        self::assertSame('["some","elements"]', $serializer->serialize(['some', 'elements']));
+        self::assertSame(['some', 'elements'], $serializer->unserialize('["some","elements"]'));
+        self::assertSame(['some', 'elements'], $serializer->unserialize(new class() implements \Stringable {
             public function __toString(): string
             {
                 return '["some","elements"]';
diff --git a/tests/Serializer/PhpSerializerTest.php b/tests/Serializer/PhpSerializerTest.php
index ab01bfe..25b73bb 100644
--- a/tests/Serializer/PhpSerializerTest.php
+++ b/tests/Serializer/PhpSerializerTest.php
@@ -17,9 +17,9 @@ public function testSerializer(): void
     {
         $serializer = new PhpSerializer();
 
-        $this->assertSame('a:2:{i:0;s:4:"some";i:1;s:8:"elements";}', $serializer->serialize(['some', 'elements']));
-        $this->assertSame(['some', 'elements'], $serializer->unserialize('a:2:{i:0;s:4:"some";i:1;s:8:"elements";}'));
-        $this->assertSame(['some', 'elements'], $serializer->unserialize(new class() implements \Stringable {
+        self::assertSame('a:2:{i:0;s:4:"some";i:1;s:8:"elements";}', $serializer->serialize(['some', 'elements']));
+        self::assertSame(['some', 'elements'], $serializer->unserialize('a:2:{i:0;s:4:"some";i:1;s:8:"elements";}'));
+        self::assertSame(['some', 'elements'], $serializer->unserialize(new class() implements \Stringable {
             public function __toString(): string
             {
                 return 'a:2:{i:0;s:4:"some";i:1;s:8:"elements";}';
@@ -30,19 +30,19 @@ public function __toString(): string
             'O:41:"Spiral\Tests\Serializer\Fixture\SomeClass":3:{s:2:"id";i:2;s:4:"text";s:4:"text";s:6:"active";b:0;}',
             SomeClass::class
         );
-        $this->assertInstanceOf(SomeClass::class, $object);
-        $this->assertSame(2, $object->id);
-        $this->assertSame('text', $object->text);
-        $this->assertFalse($object->active);
+        self::assertInstanceOf(SomeClass::class, $object);
+        self::assertSame(2, $object->id);
+        self::assertSame('text', $object->text);
+        self::assertFalse($object->active);
 
         $byInterface = $serializer->unserialize(
             'O:41:"Spiral\Tests\Serializer\Fixture\SomeClass":3:{s:2:"id";i:2;s:4:"text";s:4:"text";s:6:"active";b:0;}',
             SomeInterface::class
         );
-        $this->assertInstanceOf(SomeClass::class, $byInterface);
-        $this->assertSame(2, $byInterface->id);
-        $this->assertSame('text', $byInterface->text);
-        $this->assertFalse($byInterface->active);
+        self::assertInstanceOf(SomeClass::class, $byInterface);
+        self::assertSame(2, $byInterface->id);
+        self::assertSame('text', $byInterface->text);
+        self::assertFalse($byInterface->active);
     }
 
     public function testClassIsNotExistException(): void
diff --git a/tests/Serializer/ProtoSerializerTest.php b/tests/Serializer/ProtoSerializerTest.php
index 33da2c1..6738f32 100644
--- a/tests/Serializer/ProtoSerializerTest.php
+++ b/tests/Serializer/ProtoSerializerTest.php
@@ -23,25 +23,16 @@ public function testSerializeMessage(): void
     {
         $message = new PingRequest(['url' => 'foo']);
 
-        $this->assertSame(
-            $message->serializeToString(),
-            $this->serializer->serialize($message)
-        );
+        self::assertSame($message->serializeToString(), $this->serializer->serialize($message));
     }
 
     public function testUnserialize(): void
     {
         $message = new PingRequest(['url' => 'foo']);
 
-        $this->assertEquals(
-            $message,
-            $this->serializer->unserialize($message->serializeToString(), PingRequest::class)
-        );
+        self::assertEquals($message, $this->serializer->unserialize($message->serializeToString(), PingRequest::class));
 
-        $this->assertEquals(
-            $message,
-            $this->serializer->unserialize($message->serializeToString(), new PingRequest())
-        );
+        self::assertEquals($message, $this->serializer->unserialize($message->serializeToString(), new PingRequest()));
     }
 
     public function testInvalidPayloadException(): void
diff --git a/tests/SerializerManagerTest.php b/tests/SerializerManagerTest.php
index 7ee1e30..b1cb122 100644
--- a/tests/SerializerManagerTest.php
+++ b/tests/SerializerManagerTest.php
@@ -26,11 +26,11 @@ protected function setUp(): void
 
     public function testGetSerializer(): void
     {
-        $this->assertInstanceOf(PhpSerializer::class, $this->serializer->getSerializer('serializer'));
-        $this->assertInstanceOf(JsonSerializer::class, $this->serializer->getSerializer('json'));
+        self::assertInstanceOf(PhpSerializer::class, $this->serializer->getSerializer('serializer'));
+        self::assertInstanceOf(JsonSerializer::class, $this->serializer->getSerializer('json'));
 
         // default serializer
-        $this->assertInstanceOf(JsonSerializer::class, $this->serializer->getSerializer());
+        self::assertInstanceOf(JsonSerializer::class, $this->serializer->getSerializer());
 
         $this->expectException(SerializerNotFoundException::class);
         $this->serializer->getSerializer('bad');
@@ -39,7 +39,7 @@ public function testGetSerializer(): void
     #[DataProvider('serializeDataProvider')]
     public function testSerialize(mixed $payload, string $expected, ?string $format = null): void
     {
-        $this->assertSame($expected, $this->serializer->serialize($payload, $format));
+        self::assertSame($expected, $this->serializer->serialize($payload, $format));
     }
 
     public function testBadSerializer(): void
@@ -54,7 +54,7 @@ public function testBadSerializer(): void
     #[DataProvider('unserializeDataProvider')]
     public function testUnserialize(string|\Stringable $payload, mixed $expected, ?string $format = null): void
     {
-        $this->assertSame($expected, $this->serializer->unserialize($payload, format: $format));
+        self::assertSame($expected, $this->serializer->unserialize($payload, format: $format));
     }
 
     public static function serializeDataProvider(): \Traversable
diff --git a/tests/SerializerRegistryTest.php b/tests/SerializerRegistryTest.php
index 2710f59..d70ba12 100644
--- a/tests/SerializerRegistryTest.php
+++ b/tests/SerializerRegistryTest.php
@@ -16,16 +16,16 @@ public function testRegister(): void
     {
         $registry = new SerializerRegistry();
 
-        $this->assertFalse($registry->has('foo'));
-        $this->assertFalse($registry->has('bar'));
+        self::assertFalse($registry->has('foo'));
+        self::assertFalse($registry->has('bar'));
 
         $registry->register('foo', new PhpSerializer());
         $registry->register('bar', new JsonSerializer());
 
-        $this->assertTrue($registry->has('foo'));
-        $this->assertTrue($registry->has('bar'));
-        $this->assertInstanceOf(PhpSerializer::class, $registry->get('foo'));
-        $this->assertInstanceOf(JsonSerializer::class, $registry->get('bar'));
+        self::assertTrue($registry->has('foo'));
+        self::assertTrue($registry->has('bar'));
+        self::assertInstanceOf(PhpSerializer::class, $registry->get('foo'));
+        self::assertInstanceOf(JsonSerializer::class, $registry->get('bar'));
     }
 
     public function testGet(): void
@@ -33,7 +33,7 @@ public function testGet(): void
         $registry = new SerializerRegistry();
         $registry->register('foo', new PhpSerializer());
 
-        $this->assertInstanceOf(PhpSerializer::class, $registry->get('foo'));
+        self::assertInstanceOf(PhpSerializer::class, $registry->get('foo'));
         $this->expectException(SerializerNotFoundException::class);
         $registry->get('bar');
     }
@@ -42,13 +42,13 @@ public function testHas(): void
     {
         $registry = new SerializerRegistry();
 
-        $this->assertFalse($registry->has('foo'));
-        $this->assertFalse($registry->has('bar'));
+        self::assertFalse($registry->has('foo'));
+        self::assertFalse($registry->has('bar'));
 
         $registry->register('foo', new PhpSerializer());
         $registry->register('bar', new JsonSerializer());
 
-        $this->assertTrue($registry->has('foo'));
-        $this->assertTrue($registry->has('bar'));
+        self::assertTrue($registry->has('foo'));
+        self::assertTrue($registry->has('bar'));
     }
 }