diff --git a/src/Gelf/Transport/AbstractTransport.php b/src/Gelf/Transport/AbstractTransport.php
index 640f936..05128d1 100644
--- a/src/Gelf/Transport/AbstractTransport.php
+++ b/src/Gelf/Transport/AbstractTransport.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -12,6 +13,7 @@
 namespace Gelf\Transport;
 
 use Gelf\Encoder\EncoderInterface;
+use Gelf\Encoder\JsonEncoder;
 use Gelf\MessageInterface;
 use Gelf\PublisherInterface;
 
@@ -21,22 +23,19 @@
  *
  * @author Benjamin Zikarsky <benjamin@zikarsky.de>
  */
-abstract class AbstractTransport implements TransportInterface, PublisherInterface
+abstract class AbstractTransport implements TransportInterface
 {
+    protected EncoderInterface $messageEncoder;
 
-    /**
-     * @var EncoderInterface
-     */
-    protected $messageEncoder;
+    public function __construct(?EncoderInterface $messageEncoder = null)
+    {
+        $this->messageEncoder = $messageEncoder ?? new JsonEncoder();
+    }
 
     /**
      * Sets a message encoder
-     *
-     * @param EncoderInterface $encoder
-     *
-     * @return $this
      */
-    public function setMessageEncoder(EncoderInterface $encoder)
+    public function setMessageEncoder(EncoderInterface $encoder): self
     {
         $this->messageEncoder = $encoder;
 
@@ -45,27 +44,9 @@ public function setMessageEncoder(EncoderInterface $encoder)
 
     /**
      * Returns the current message encoder
-     *
-     * @return EncoderInterface
      */
-    public function getMessageEncoder()
+    public function getMessageEncoder(): EncoderInterface
     {
         return $this->messageEncoder;
     }
-
-    /**
-     * Alias to send() without return value
-     * Required to fulfill the PublisherInterface
-     *
-     * @deprecated deprecated since 1.1
-     * @codeCoverageIgnore
-     *
-     * @param MessageInterface $message
-     *
-     * @return int the number of bytes sent
-     */
-    public function publish(MessageInterface $message)
-    {
-        return $this->send($message);
-    }
 }
diff --git a/src/Gelf/Transport/AmqpTransport.php b/src/Gelf/Transport/AmqpTransport.php
index e156831..6ff28a5 100644
--- a/src/Gelf/Transport/AmqpTransport.php
+++ b/src/Gelf/Transport/AmqpTransport.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -24,37 +25,23 @@
  */
 class AmqpTransport extends AbstractTransport
 {
-    /**
-     * @var AMQPExchange $exchange
-     */
-    protected $exchange;
-
-    /**
-     * @var AMQPQueue $exchange
-     */
-    protected $queue;
-
-    /**
-     * @param AMQPExchange $exchange
-     * @param AMQPQueue $queue
-     */
-    public function __construct(AMQPExchange $exchange, AMQPQueue $queue)
-    {
-        $this->queue = $queue;
-        $this->exchange = $exchange;
-        $this->messageEncoder = new DefaultEncoder();
+    public function __construct(
+        private AMQPExchange $exchange,
+        private AMQPQueue $queue
+    ) {
+        parent::__construct();
     }
 
     /**
      * @inheritdoc
      */
-    public function send(Message $message)
+    public function send(Message $message): int
     {
         $rawMessage = $this->getMessageEncoder()->encode($message);
 
-        $attributes = array(
+        $attributes = [
             'Content-type' => 'application/json'
-        );
+        ];
 
         // if queue is durable then mark message as 'persistent'
         if (($this->queue->getFlags() & AMQP_DURABLE) > 0) {
diff --git a/src/Gelf/Transport/HttpTransport.php b/src/Gelf/Transport/HttpTransport.php
index 217a7e7..ae7e0b3 100644
--- a/src/Gelf/Transport/HttpTransport.php
+++ b/src/Gelf/Transport/HttpTransport.php
@@ -27,76 +27,29 @@
  */
 class HttpTransport extends AbstractTransport
 {
-    const DEFAULT_HOST = "127.0.0.1";
-    const DEFAULT_PORT = 12202;
-    const DEFAULT_PATH = "/gelf";
-    
-    const AUTO_SSL_PORT = 443;
-    
-    /**
-     * @var string
-     */
-    protected $host;
-
-    /**
-     * @var int
-     */
-    protected $port;
-
-    /**
-     * @var string
-     */
-    protected $path;
-
-    /**
-     * @var StreamSocketClient
-     */
-    protected $socketClient;
-
-    /**
-     * @var SslOptions|null
-     */
-    protected $sslOptions = null;
-
-    /**
-     * @var string|null
-     */
-    protected $authentication = null;
+    private const DEFAULT_HOST = "127.0.0.1";
+    private const DEFAULT_PORT = 12202;
+    private const DEFAULT_PATH = "/gelf";
+    private const AUTO_SSL_PORT = 443;
 
-    /**
-     * @var string|null
-     */
-    protected $proxyUri = null;
+    private StreamSocketClient $socketClient;
 
-    /**
-     * @var bool
-     */
-    protected $requestFullUri = false;
+    private ?string $authentication = null;
+    private ?string $proxyUri = null;
+    private ?bool $requestFullUri = false;
 
-    /**
-     * Class constructor
-     *
-     * @param string|null     $host       when NULL or empty default-host is used
-     * @param int|null        $port       when NULL or empty default-port is used
-     * @param string|null     $path       when NULL or empty default-path is used
-     * @param SslOptions|null $sslOptions when null not SSL is used
-     */
     public function __construct(
-        $host = self::DEFAULT_HOST,
-        $port = self::DEFAULT_PORT,
-        $path = self::DEFAULT_PATH,
-        SslOptions $sslOptions = null
+        private string $host = self::DEFAULT_HOST,
+        private int $port = self::DEFAULT_PORT,
+        private string $path = self::DEFAULT_PATH,
+        private ?SslOptions $sslOptions = null
     ) {
-        $this->host = $host;
-        $this->port = $port;
-        $this->path = $path;
+        parent::__construct();
 
-        if ($port == self::AUTO_SSL_PORT && $sslOptions == null) {
-            $sslOptions = new SslOptions();
+        if ($port == self::AUTO_SSL_PORT && $sslOptions === null) {
+            $this->sslOptions = new SslOptions();
         }
 
-        $this->sslOptions = $sslOptions;
-        $this->messageEncoder = new DefaultEncoder();
         $this->socketClient = new StreamSocketClient(
             $this->getScheme(),
             $this->host,
@@ -113,13 +66,8 @@ public function __construct(
      * If a username but no password is given, and empty password is used.
      * If a https URI is given, the provided SslOptions (with a fallback to
      * the default SslOptions) are used.
-     *
-     * @param  string          $url
-     * @param  SslOptions|null $sslOptions
-     *
-     * @return HttpTransport
      */
-    public static function fromUrl($url, SslOptions $sslOptions = null)
+    public static function fromUrl(string $url, ?SslOptions $sslOptions = null): static
     {
         $parsed = parse_url($url);
         
@@ -130,12 +78,12 @@ public static function fromUrl($url, SslOptions $sslOptions = null)
         
         // check it's http or https
         $scheme = strtolower($parsed['scheme']);
-        if (!in_array($scheme, array('http', 'https'))) {
+        if (!in_array($scheme, ['http', 'https'])) {
             throw new \InvalidArgumentException("$url is not a valid http/https URL");
         }
 
         // setup defaults
-        $defaults = array('port' => 80, 'path' => '', 'user' => null, 'pass' => '');
+        $defaults = ['port' => 80, 'path' => '', 'user' => null, 'pass' => ''];
 
         // change some defaults for https
         if ($scheme == 'https') {
@@ -157,22 +105,16 @@ public static function fromUrl($url, SslOptions $sslOptions = null)
 
     /**
      * Sets HTTP basic authentication
-     *
-     * @param string $username
-     * @param string $password
      */
-    public function setAuthentication($username, $password)
+    public function setAuthentication(string $username, string $password): void
     {
         $this->authentication = $username . ":" . $password;
     }
 
     /**
      * Enables HTTP proxy
-     *
-     * @param $proxyUri
-     * @param bool $requestFullUri
      */
-    public function setProxy($proxyUri, $requestFullUri = false)
+    public function setProxy(string $proxyUri, bool $requestFullUri = false): void
     {
         $this->proxyUri = $proxyUri;
         $this->requestFullUri = $requestFullUri;
@@ -181,25 +123,21 @@ public function setProxy($proxyUri, $requestFullUri = false)
     }
 
     /**
-     * Sends a Message over this transport
-     *
-     * @param MessageInterface $message
-     *
-     * @return int the number of bytes sent
+     * @inheritDoc
      */
-    public function send(MessageInterface $message)
+    public function send(MessageInterface $message): int
     {
         $messageEncoder = $this->getMessageEncoder();
         $rawMessage = $messageEncoder->encode($message);
 
-        $request = array(
+        $request = [
             sprintf("POST %s HTTP/1.1", $this->path),
             sprintf("Host: %s:%d", $this->host, $this->port),
             sprintf("Content-Length: %d", strlen($rawMessage)),
             "Content-Type: application/json",
             "Connection: Keep-Alive",
             "Accept: */*"
-        );
+        ];
 
         if (null !== $this->authentication) {
             $request[] = "Authorization: Basic " . base64_encode($this->authentication);
@@ -219,7 +157,7 @@ public function send(MessageInterface $message)
 
         // if we don't have a HTTP/1.1 connection, or the server decided to close the connection
         // we should do so as well. next read/write-attempt will open a new socket in this case.
-        if (strpos($headers, "HTTP/1.1") !== 0 || preg_match("!Connection:\s*Close!i", $headers)) {
+        if (!str_starts_with($headers, "HTTP/1.1") || preg_match("!Connection:\s*Close!i", $headers)) {
             $this->socketClient->close();
         }
 
@@ -235,10 +173,7 @@ public function send(MessageInterface $message)
         return $byteCount;
     }
 
-    /**
-     * @return string
-     */
-    private function readResponseHeaders()
+    private function readResponseHeaders(): string
     {
         $chunkSize = 1024; // number of bytes to read at once
         $delimiter = "\r\n\r\n"; // delimiter between headers and response
@@ -247,37 +182,31 @@ private function readResponseHeaders()
         do {
             $chunk = $this->socketClient->read($chunkSize);
             $response .= $chunk;
-        } while (false === strpos($chunk, $delimiter) && strlen($chunk) > 0);
+        } while (!str_contains($chunk, $delimiter) && strlen($chunk) > 0);
 
         $elements = explode($delimiter, $response, 2);
 
         return $elements[0];
     }
 
-    /**
-     * @return string
-     */
-    private function getScheme()
+    private function getScheme(): string
     {
         return null === $this->sslOptions ? 'tcp' : 'ssl';
     }
 
-    /**
-     * @return array
-     */
-    private function getContext()
+    private function getContext(): array
     {
-        $options = array();
+        $options = [];
 
         if (null !== $this->sslOptions) {
             $options = array_merge($options, $this->sslOptions->toStreamContext($this->host));
         }
 
         if (null !== $this->proxyUri) {
-            $options['http'] = array(
+            $options['http'] = [
                 'proxy' => $this->proxyUri,
                 'request_fulluri' => $this->requestFullUri
-            );
+            ];
         }
 
         return $options;
@@ -285,20 +214,16 @@ private function getContext()
 
     /**
      * Sets the connect-timeout
-     *
-     * @param int $timeout
      */
-    public function setConnectTimeout($timeout)
+    public function setConnectTimeout(int $timeout): void
     {
         $this->socketClient->setConnectTimeout($timeout);
     }
 
     /**
      * Returns the connect-timeout
-     *
-     * @return int
      */
-    public function getConnectTimeout()
+    public function getConnectTimeout(): int
     {
         return $this->socketClient->getConnectTimeout();
     }
diff --git a/src/Gelf/Transport/IgnoreErrorTransportWrapper.php b/src/Gelf/Transport/IgnoreErrorTransportWrapper.php
index fb1a350..bd1e1e9 100644
--- a/src/Gelf/Transport/IgnoreErrorTransportWrapper.php
+++ b/src/Gelf/Transport/IgnoreErrorTransportWrapper.php
@@ -1,48 +1,32 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Transport;
 
 use Gelf\MessageInterface as Message;
+use Throwable;
 
 /**
  * A wrapper for any AbstractTransport to ignore any kind of errors
  * @package Gelf\Transport
  */
-class IgnoreErrorTransportWrapper extends AbstractTransport
+class IgnoreErrorTransportWrapper implements TransportInterface
 {
+    private ?Throwable $lastError = null;
 
-    /**
-     * @var AbstractTransport
-     */
-    private $transport;
-
-    /**
-     * @var \Exception|null
-     */
-    private $lastError = null;
-
-    /**
-     * IgnoreErrorTransportWrapper constructor.
-     *
-     * @param AbstractTransport $transport
-     */
-    public function __construct(AbstractTransport $transport)
-    {
-        $this->transport = $transport;
+    public function __construct(
+        private TransportInterface $transport
+    ) {
     }
 
     /**
-     * Sends a Message over this transport.
-     *
-     * @param Message $message
-     *
-     * @return int the number of bytes sent
+     * @inheritDoc
      */
-    public function send(Message $message)
+    public function send(Message $message): int
     {
         try {
             return $this->transport->send($message);
-        } catch (\Exception $e) {
+        } catch (Throwable $e) {
             $this->lastError = $e;
             return 0;
         }
@@ -50,9 +34,8 @@ public function send(Message $message)
 
     /**
      * Returns the last error
-     * @return \Exception|null
      */
-    public function getLastError()
+    public function getLastError(): ?Throwable
     {
         return $this->lastError;
     }
diff --git a/src/Gelf/Transport/KeepAliveRetryTransportWrapper.php b/src/Gelf/Transport/KeepAliveRetryTransportWrapper.php
index 6588255..7207b3e 100644
--- a/src/Gelf/Transport/KeepAliveRetryTransportWrapper.php
+++ b/src/Gelf/Transport/KeepAliveRetryTransportWrapper.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Transport;
 
@@ -6,14 +7,9 @@
 
 class KeepAliveRetryTransportWrapper extends RetryTransportWrapper
 {
-    /**
-     * @const string
-     */
-    const NO_RESPONSE = "Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''";
+    private const NO_RESPONSE
+        = "Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''";
 
-    /**
-     * @param HttpTransport $transport
-     */
     public function __construct(HttpTransport $transport)
     {
         parent::__construct($transport, 1, function (RuntimeException $e) {
diff --git a/src/Gelf/Transport/RetryTransportWrapper.php b/src/Gelf/Transport/RetryTransportWrapper.php
index 489eb3e..f1b02ec 100644
--- a/src/Gelf/Transport/RetryTransportWrapper.php
+++ b/src/Gelf/Transport/RetryTransportWrapper.php
@@ -1,62 +1,38 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Transport;
 
+use Closure;
 use Gelf\MessageInterface as Message;
-use RuntimeException;
+use Throwable;
 
-class RetryTransportWrapper extends AbstractTransport
+class RetryTransportWrapper implements TransportInterface
 {
-    /**
-     * @const string
-     */
-    const NO_RESPONSE = "Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''";
-
-    /**
-     * @var TransportInterface
-     */
-    protected $transport;
-
-    /**
-     * @var int
-     */
-    protected $maxRetries;
-
-    /**
-     * @var callable|null
-     */
-    protected $exceptionMatcher;
+    protected Closure $exceptionMatcher;
 
     /**
      * KeepAliveRetryTransportWrapper constructor.
      *
-     * @param TransportInterface $transport
-     * @param int $maxRetries
-     * @param callable(\Throwable):bool $exceptionMatcher
+     * @param null|callable(Throwable):bool $exceptionMatcher
      */
-    public function __construct(TransportInterface $transport, $maxRetries, $exceptionMatcher = null)
-    {
-        $this->transport = $transport;
-        $this->maxRetries = $maxRetries;
-        $this->exceptionMatcher = $exceptionMatcher;
+    public function __construct(
+        private TransportInterface $transport,
+        private int $maxRetries,
+        ?callable $exceptionMatcher = null
+    ) {
+        $this->exceptionMatcher = Closure::fromCallable($exceptionMatcher ?? fn (Throwable $_) => true);
     }
 
-    /**
-     * @return TransportInterface
-     */
-    public function getTransport()
+    public function getTransport(): TransportInterface
     {
         return $this->transport;
     }
 
     /**
-     * Sends a Message over this transport.
-     *
-     * @param Message $message
-     *
-     * @return int calls function to send message
+     * @inheritDoc
      */
-    public function send(Message $message)
+    public function send(Message $message): int
     {
         $tries = 0;
 
@@ -64,12 +40,12 @@ public function send(Message $message)
             try {
                 $tries++;
                 return $this->transport->send($message);
-            } catch (\Exception $e) {
+            } catch (Throwable $e) {
                 if ($this->maxRetries !== 0 && $tries > $this->maxRetries) {
                     throw $e;
                 }
 
-                if ($this->exceptionMatcher && !call_user_func($this->exceptionMatcher, $e)) {
+                if (!call_user_func($this->exceptionMatcher, $e)) {
                     throw $e;
                 }
             }
diff --git a/src/Gelf/Transport/SslOptions.php b/src/Gelf/Transport/SslOptions.php
index 4fda266..ccb98cd 100644
--- a/src/Gelf/Transport/SslOptions.php
+++ b/src/Gelf/Transport/SslOptions.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -12,7 +13,7 @@
 namespace Gelf\Transport;
 
 /**
- * Abstraction of supported SSL configuration paramaters
+ * Abstraction of supported SSL configuration parameters
  *
  * @author Benjamin Zikarsky <benjamin@zikarsky.de>
  */
@@ -20,80 +21,62 @@ class SslOptions
 {
     /**
      * Enable certificate validation of remote party
-     *
-     * @param boolean
      */
-    protected $verifyPeer = true;
+    private bool $verifyPeer = true;
 
     /**
      * Allow self-signed certificates
-     *
-     * @param boolean
      */
-    protected $allowSelfSigned = false;
+    private bool $allowSelfSigned = false;
 
     /**
      * Path to custom CA
-     *
-     * @param string|null
      */
-    protected $caFile = null;
+    private ?string $caFile = null;
 
     /**
      * List of ciphers the SSL layer may use
      *
      * Formatted as specified in `ciphers(1)`
-     *
-     * @param string|null
      */
-    protected $ciphers = null;
+    private ?string $ciphers = null;
 
     /**
      * Whether self-signed certificates are allowed
-     *
-     * @return boolean
      */
-    public function getAllowSelfSigned()
+    public function getAllowSelfSigned(): bool
     {
         return $this->allowSelfSigned;
     }
 
     /**
      * Enables or disables the error on self-signed certificates
-     *
-     * @param boolean $allowSelfSigned
      */
-    public function setAllowSelfSigned($allowSelfSigned)
+    public function setAllowSelfSigned(bool $allowSelfSigned): void
     {
         $this->allowSelfSigned = $allowSelfSigned;
     }
 
     /**
      * Returns the path to a custom CA
-     *
-     * @return string|null
      */
-    public function getCaFile()
+    public function getCaFile(): ?string
     {
         return $this->caFile;
     }
 
     /**
      * Sets the path toa custom CA
-     *
-     * @param string|null $caFile
      */
-    public function setCaFile($caFile)
+    public function setCaFile(?string $caFile): void
     {
         $this->caFile = $caFile;
     }
 
     /**
      * Returns des description of allowed ciphers
-     *
-     * @return string|null
      */
-    public function getCiphers()
+    public function getCiphers(): ?string
     {
         return $this->ciphers;
     }
@@ -102,46 +85,37 @@ public function getCiphers()
      * Set the allowed SSL/TLS ciphers
      *
      * Format must follow `ciphers(1)`
-     *
-     * @param string|null $ciphers
      */
-    public function setCiphers($ciphers)
+    public function setCiphers(?string $ciphers): void
     {
         $this->ciphers = $ciphers;
     }
 
     /**
      * Whether to check the peer certificate
-     *
-     * @return boolean
      */
-    public function getVerifyPeer()
+    public function getVerifyPeer(): bool
     {
         return $this->verifyPeer;
     }
 
     /**
      * Enable or disable the peer certificate check
-     *
-     * @param boolean $verifyPeer
      */
-    public function setVerifyPeer($verifyPeer)
+    public function setVerifyPeer(bool $verifyPeer): void
     {
         $this->verifyPeer = $verifyPeer;
     }
 
     /**
      * Returns a stream-context representation of this config
-     *
-     * @param string|null $serverName
-     * @return array<string,mixed>
      */
-    public function toStreamContext($serverName = null)
+    public function toStreamContext(?string $serverName = null): array
     {
-        $sslContext = array(
-            'verify_peer'       => (bool) $this->verifyPeer,
-            'allow_self_signed' => (bool) $this->allowSelfSigned
-        );
+        $sslContext = [
+            'verify_peer'       => $this->verifyPeer,
+            'allow_self_signed' => $this->allowSelfSigned
+        ];
 
         if (null !== $this->caFile) {
             $sslContext['cafile'] = $this->caFile;
@@ -160,6 +134,6 @@ public function toStreamContext($serverName = null)
             }
         }
 
-        return array('ssl' => $sslContext);
+        return ['ssl' => $sslContext];
     }
 }
diff --git a/src/Gelf/Transport/StreamSocketClient.php b/src/Gelf/Transport/StreamSocketClient.php
index 2b6add1..1cd7b8a 100644
--- a/src/Gelf/Transport/StreamSocketClient.php
+++ b/src/Gelf/Transport/StreamSocketClient.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -23,53 +24,17 @@
  */
 class StreamSocketClient
 {
-    /**
-     * @deprecated deprecated since v1.4.0
-     */
-    const SOCKET_TIMEOUT = 30;
+    private const DEFAULT_SOCKET_TIMEOUT = 30;
 
-    /**
-     * @var string
-     */
-    protected $host;
+    private mixed $socket = null;
+    private int $connectTimeout = self::DEFAULT_SOCKET_TIMEOUT;
 
-    /**
-     * @var integer
-     */
-    protected $port;
-
-    /**
-     * @var string
-     */
-    protected $scheme;
-
-    /**
-     * @var array
-     */
-    protected $context;
-
-    /**
-     * @var resource
-     */
-    protected $socket;
-
-    /**
-     * @var int
-     */
-    protected $connectTimeout = self::SOCKET_TIMEOUT;
-
-    /**
-     * @param string  $scheme
-     * @param string  $host
-     * @param integer $port
-     * @param array   $context
-     */
-    public function __construct($scheme, $host, $port, array $context = array())
-    {
-        $this->scheme = $scheme;
-        $this->host = $host;
-        $this->port = $port;
-        $this->context = $context;
+    public function __construct(
+        private string $scheme,
+        private string $host,
+        private int $port,
+        private array $context = []
+    ) {
     }
 
     /**
@@ -80,51 +45,6 @@ public function __destruct()
         $this->close();
     }
 
-    /**
-     * Initializes socket-client
-     *
-     * @deprecated deprecated since v1.4.0
-     *
-     * @param string  $scheme  like "udp" or "tcp"
-     * @param string  $host
-     * @param integer $port
-     * @param array   $context
-     *
-     * @return resource
-     *
-     * @throws RuntimeException on connection-failure
-     */
-    protected static function initSocket($scheme, $host, $port, array $context)
-    {
-        $socketDescriptor = sprintf("%s://%s:%d", $scheme, $host, $port);
-        $socket = @stream_socket_client(
-            $socketDescriptor,
-            $errNo,
-            $errStr,
-            static::SOCKET_TIMEOUT,
-            \STREAM_CLIENT_CONNECT,
-            stream_context_create($context)
-        );
-
-        if ($socket === false) {
-            throw new RuntimeException(
-                sprintf(
-                    "Failed to create socket-client for %s: %s (%s)",
-                    $socketDescriptor,
-                    $errStr,
-                    $errNo
-                )
-            );
-        }
-
-        // set non-blocking for UDP
-        if (strcasecmp("udp", $scheme) == 0) {
-            stream_set_blocking($socket, 0);
-        }
-
-        return $socket;
-    }
-
 
     /**
      * Internal function mimicking the behaviour of static::initSocket
@@ -135,7 +55,7 @@ protected static function initSocket($scheme, $host, $port, array $context)
      *
      * @throws RuntimeException on connection-failure
      */
-    private function buildSocket()
+    private function buildSocket(): mixed
     {
         $socketDescriptor = sprintf(
             "%s://%s:%d",
@@ -166,7 +86,7 @@ private function buildSocket()
 
         // set non-blocking for UDP
         if (strcasecmp("udp", $this->scheme) == 0) {
-            stream_set_blocking($socket, 0);
+            stream_set_blocking($socket, true);
         }
 
         return $socket;
@@ -177,7 +97,7 @@ private function buildSocket()
      *
      * @return resource
      */
-    public function getSocket()
+    public function getSocket(): mixed
     {
         // lazy initializing of socket-descriptor
         if (!$this->socket) {
@@ -190,25 +110,18 @@ public function getSocket()
     /**
      * Writes a given string to the socket and returns the
      * number of written bytes
-     *
-     * @param string $buffer
-     *
-     * @return int
-     *
-     * @throws RuntimeException on write-failure
      */
-    public function write($buffer)
+    public function write(string $buffer): int
     {
-        $buffer = (string) $buffer;
         $bufLen = Binary::safeStrlen($buffer);
 
         $socket = $this->getSocket();
         $written = 0;
 
         while ($written < $bufLen) {
-            // PHP's fwrite does not behave nice in regards to errors, so we wrap
+            // PHP's fwrite does not behave nice in regard to errors, so we wrap
             // it with a temporary error handler and treat every warning/notice as
-            // a error
+            // an error
             $failed = false;
             $errorMessage = "Failed to write to socket";
             set_error_handler(function ($errno, $errstr) use (&$failed, &$errorMessage) {
@@ -223,7 +136,7 @@ public function write($buffer)
             }
 
             if ($failed || $byteCount === false) {
-                throw new \RuntimeException($errorMessage);
+                throw new RuntimeException($errorMessage);
             }
 
             $written += $byteCount;
@@ -235,12 +148,8 @@ public function write($buffer)
 
     /**
      * Reads a given number of bytes from the socket
-     *
-     * @param integer $byteCount
-     *
-     * @return string
      */
-    public function read($byteCount)
+    public function read(int $byteCount): string
     {
         return fread($this->getSocket(), $byteCount);
     }
@@ -248,7 +157,7 @@ public function read($byteCount)
     /**
      * Closes underlying socket explicitly
      */
-    public function close()
+    public function close(): void
     {
         if (!is_resource($this->socket)) {
             return;
@@ -260,30 +169,24 @@ public function close()
 
     /**
      * Checks if the socket is closed
-     *
-     * @return bool
      */
-    public function isClosed()
+    public function isClosed(): bool
     {
         return $this->socket === null;
     }
 
     /**
      * Returns the current connect-timeout
-     *
-     * @return int
      */
-    public function getConnectTimeout()
+    public function getConnectTimeout(): int
     {
         return $this->connectTimeout;
     }
 
     /**
      * Sets the connect-timeout
-     *
-     * @param int $timeout
      */
-    public function setConnectTimeout($timeout)
+    public function setConnectTimeout(int $timeout): void
     {
         if (!$this->isClosed()) {
             throw new \LogicException("Cannot change socket properties with an open connection");
@@ -294,20 +197,16 @@ public function setConnectTimeout($timeout)
 
     /**
      * Returns the stream context
-     *
-     * @return array
      */
-    public function getContext()
+    public function getContext(): array
     {
         return $this->context;
     }
 
     /**
      * Sets the stream context
-     *
-     * @param array $context
      */
-    public function setContext(array $context)
+    public function setContext(array $context): void
     {
         if (!$this->isClosed()) {
             throw new \LogicException("Cannot change socket properties with an open connection");
diff --git a/src/Gelf/Transport/TcpTransport.php b/src/Gelf/Transport/TcpTransport.php
index 5eb6c2c..8a47a2f 100644
--- a/src/Gelf/Transport/TcpTransport.php
+++ b/src/Gelf/Transport/TcpTransport.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -29,53 +30,23 @@
  */
 class TcpTransport extends AbstractTransport
 {
-    const DEFAULT_HOST = "127.0.0.1";
-    const DEFAULT_PORT = 12201;
+    private const DEFAULT_HOST = "127.0.0.1";
+    private const DEFAULT_PORT = 12201;
+    private const AUTO_SSL_PORT = 12202;
 
-    const AUTO_SSL_PORT = 12202;
+    private StreamSocketClient $socketClient;
 
-    /**
-     * @var string
-     */
-    protected $host;
-
-    /**
-     * @var int
-     */
-    protected $port;
-
-    /**
-     * @var StreamSocketClient
-     */
-    protected $socketClient;
-
-    /**
-     * @var SslOptions|null
-     */
-    protected $sslOptions = null;
-
-    /**
-     * Class constructor
-     *
-     * @param string|null     $host       when NULL or empty default-host is used
-     * @param int|null        $port       when NULL or empty default-port is used
-     * @param SslOptions|null $sslOptions when null not SSL is used
-     */
     public function __construct(
-        $host = self::DEFAULT_HOST,
-        $port = self::DEFAULT_PORT,
-        SslOptions $sslOptions = null
+        private string $host = self::DEFAULT_HOST,
+        private int $port = self::DEFAULT_PORT,
+        private ?SslOptions $sslOptions = null
     ) {
-        $this->host = $host;
-        $this->port = $port;
+        parent::__construct();
 
-        if ($port == self::AUTO_SSL_PORT && $sslOptions == null) {
-            $sslOptions = new SslOptions();
+        if ($port == self::AUTO_SSL_PORT && $this->sslOptions == null) {
+            $this->sslOptions = new SslOptions();
         }
 
-        $this->sslOptions = $sslOptions;
-
-        $this->setMessageEncoder(new DefaultEncoder());
         $this->socketClient = new StreamSocketClient(
             $this->getScheme(),
             $this->host,
@@ -85,37 +56,25 @@ public function __construct(
     }
 
     /**
-     * Sends a Message over this transport
-     *
-     * @param Message $message
-     *
-     * @return int the number of TCP packets sent
+     * @inheritDoc
      */
-    public function send(Message $message)
+    public function send(Message $message): int
     {
         $rawMessage = $this->getMessageEncoder()->encode($message) . "\0";
 
         // send message in one packet
-        $this->socketClient->write($rawMessage);
-
-        return 1;
+        return $this->socketClient->write($rawMessage);
     }
 
-    /**
-     * @return string
-     */
-    private function getScheme()
+    private function getScheme(): string
     {
         return null === $this->sslOptions ? 'tcp' : 'ssl';
     }
 
-    /**
-     * @return array
-     */
-    private function getContext()
+    private function getContext(): array
     {
         if (null === $this->sslOptions) {
-            return array();
+            return [];
         }
 
         return $this->sslOptions->toStreamContext($this->host);
@@ -123,25 +82,21 @@ private function getContext()
 
     /**
      * Sets the connect-timeout
-     *
-     * @param int $timeout
      */
-    public function setConnectTimeout($timeout)
+    public function setConnectTimeout(int $timeout): void
     {
         $this->socketClient->setConnectTimeout($timeout);
     }
 
     /**
      * Returns the connect-timeout
-     *
-     * @return int
      */
-    public function getConnectTimeout()
+    public function getConnectTimeout(): int
     {
         return $this->socketClient->getConnectTimeout();
     }
 
-    public function setMessageEncoder(EncoderInterface $encoder)
+    public function setMessageEncoder(EncoderInterface $encoder): self
     {
         if (!$encoder instanceof NoNullByteEncoderInterface) {
             throw new InvalidArgumentException(
diff --git a/src/Gelf/Transport/TransportInterface.php b/src/Gelf/Transport/TransportInterface.php
index afd2ec3..93ce196 100644
--- a/src/Gelf/Transport/TransportInterface.php
+++ b/src/Gelf/Transport/TransportInterface.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -24,8 +25,7 @@ interface TransportInterface
     /**
      * Sends a Message over this transport.
      *
-     * @param Message $message
-     * @return int the number of bytes sent
+     * @return int an indicator over the amount sent (can be messages, packages, bytes,...)
      */
-    public function send(Message $message);
+    public function send(Message $message): int;
 }
diff --git a/src/Gelf/Transport/UdpTransport.php b/src/Gelf/Transport/UdpTransport.php
index cb0ee43..f16d678 100644
--- a/src/Gelf/Transport/UdpTransport.php
+++ b/src/Gelf/Transport/UdpTransport.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -27,24 +28,17 @@
  */
 class UdpTransport extends AbstractTransport
 {
-    const CHUNK_GELF_ID = "\x1e\x0f";
-    const CHUNK_MAX_COUNT = 128; // as per GELF spec
-    const CHUNK_SIZE_LAN = 8154;
-    const CHUNK_SIZE_WAN = 1420;
-    const CHUNK_HEADER_LENGTH = 12; // GELF ID (2b), id (8b) , sequence (2b)
-
-    const DEFAULT_HOST = "127.0.0.1";
-    const DEFAULT_PORT = 12201;
-
-    /**
-     * @var int
-     */
-    protected $chunkSize;
-
-    /**
-     * @var StreamSocketClient
-     */
-    protected $socketClient;
+    private const CHUNK_GELF_ID = "\x1e\x0f";
+    private const CHUNK_MAX_COUNT = 128; // as per GELF spec
+    private const CHUNK_HEADER_LENGTH = 12; // GELF ID (2b), id (8b) , sequence (2b)
+    
+    public const CHUNK_SIZE_LAN = 8154;
+    public const CHUNK_SIZE_WAN = 1420;
+
+    private const DEFAULT_HOST = "127.0.0.1";
+    private const DEFAULT_PORT = 12201;
+    
+    private StreamSocketClient $socketClient;
 
     /**
      * Class constructor
@@ -55,18 +49,17 @@ class UdpTransport extends AbstractTransport
      *                          0 disables chunks completely
      */
     public function __construct(
-        $host = self::DEFAULT_HOST,
-        $port = self::DEFAULT_PORT,
-        $chunkSize = self::CHUNK_SIZE_WAN
+        string $host = self::DEFAULT_HOST,
+        int $port = self::DEFAULT_PORT,
+        private int $chunkSize = self::CHUNK_SIZE_WAN
     ) {
+        parent::__construct();
+
         // allow NULL-like values for fallback on default
         $host = $host ?: self::DEFAULT_HOST;
         $port = $port ?: self::DEFAULT_PORT;
 
         $this->socketClient = new StreamSocketClient('udp', $host, $port);
-        $this->chunkSize = $chunkSize;
-
-        $this->messageEncoder = new DefaultEncoder();
 
         if ($chunkSize > 0 && $chunkSize <= self::CHUNK_HEADER_LENGTH) {
             throw new InvalidArgumentException('Chunk-size has to exceed ' . self::CHUNK_HEADER_LENGTH
@@ -75,13 +68,9 @@ public function __construct(
     }
 
     /**
-     * Sends a Message over this transport
-     *
-     * @param Message $message
-     *
-     * @return int the number of UDP packets sent
+     * @inheritDoc
      */
-    public function send(Message $message)
+    public function send(Message $message): int
     {
         $rawMessage = $this->getMessageEncoder()->encode($message);
 
@@ -100,14 +89,8 @@ public function send(Message $message)
 
     /**
      * Sends given string in multiple chunks
-     *
-     * @param string $rawMessage
-     * @return int
-     *
-     * @throws RuntimeException on too large messages which would exceed the
-     * maximum number of possible chunks
      */
-    protected function sendMessageInChunks($rawMessage)
+    private function sendMessageInChunks(string $rawMessage): int
     {
         // split to chunks
         $chunks = str_split($rawMessage, $this->chunkSize - self::CHUNK_HEADER_LENGTH);
diff --git a/tests/Gelf/Test/Transport/AmqpTransportTest.php b/tests/Gelf/Test/Transport/AmqpTransportTest.php
deleted file mode 100644
index 5fb7ef5..0000000
--- a/tests/Gelf/Test/Transport/AmqpTransportTest.php
+++ /dev/null
@@ -1,150 +0,0 @@
-<?php
-
-/*
- * This file is part of the php-gelf package.
- *
- * (c) Benjamin Zikarsky <http://benjamin-zikarsky.de>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Gelf\Test\Transport;
-
-use Gelf\Transport\AmqpTransport;
-use PHPUnit\Framework\TestCase;
-
-class AmqpTransportTest extends TestCase
-{
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $message;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject | \Gelf\Encoder\EncoderInterface
-     */
-    protected $encoder;
-    /**
-     * @var string
-     */
-    protected $testMessage;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject | AmqpTransport
-     */
-    protected $transport;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject | \AMQPExchange
-     */
-    protected $exchange;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject | \AMQPQueue
-     */
-    protected $queue;
-
-    public function setUp()
-    {
-        if (!extension_loaded('amqp')) {
-            $this->markTestSkipped('Requires ext-amqp');
-            return;
-        }
-
-        if (!defined('AMQP_NOPARAM')) {
-            define('AMQP_NOPARAM', 0);
-        }
-
-        if (!defined('AMQP_DURABLE')) {
-            define('AMQP_DURABLE', 2);
-        }
-
-        $this->testMessage = str_repeat("0123456789", 30); // 300 char string
-
-        $this->exchange = $this->createMock(
-            "\\AMQPExchange",
-            $methods = array('publish'),
-            $args = array(),
-            $mockClassName = '',
-            $callConstructor = false
-        );
-        $this->queue = $this->createMock(
-            "\\AMQPQueue",
-            $methods = array('getName', 'getFlags'),
-            $args = array(),
-            $mockClassName = '',
-            $callConstructor = false
-        );
-
-        $this->message = $this->createMock("\\Gelf\\Message");
-
-        // create an encoder always return $testMessage
-        $this->encoder = $this->createMock("\\Gelf\\Encoder\\EncoderInterface");
-        $this->encoder->expects($this->any())->method('encode')->will(
-            $this->returnValue($this->testMessage)
-        );
-        $this->transport = $this->getTransport(0);
-    }
-
-    protected function getTransport()
-    {
-        $transport = new AmqpTransport($this->exchange, $this->queue);
-        $transport->setMessageEncoder($this->encoder);
-
-        $reflectedTransport = new \ReflectionObject($transport);
-
-        $reflectedExchange = $reflectedTransport->getProperty('exchange');
-        $reflectedExchange->setAccessible(true);
-        $reflectedExchange->setValue($transport, $this->exchange);
-
-        $reflectedQueue = $reflectedTransport->getProperty('queue');
-        $reflectedQueue->setAccessible(true);
-        $reflectedQueue->setValue($transport, $this->queue);
-
-        return $transport;
-    }
-
-    public function testSetEncoder()
-    {
-        $encoder = $this->createMock('\\Gelf\\Encoder\\EncoderInterface');
-        $this->transport->setMessageEncoder($encoder);
-
-        $this->assertEquals($encoder, $this->transport->getMessageEncoder());
-    }
-
-    public function testGetEncoder()
-    {
-        $transport = new AmqpTransport($this->exchange, $this->queue);
-        $this->assertInstanceOf(
-            "\\Gelf\\Encoder\\EncoderInterface",
-            $transport->getMessageEncoder()
-        );
-    }
-
-    public function testPublish()
-    {
-        $transport = $this->getMockBuilder("\\Gelf\\Transport\\HttpTransport")
-            ->setMethods(array("send"))
-            ->disableOriginalConstructor()
-            ->getMock();
-
-        $transport
-            ->expects($this->once())
-            ->method("send")
-            ->with($this->message)
-            ->willReturn(42);
-
-        $response = $transport->publish($this->message);
-
-        $this->assertSame(42, $response);
-    }
-
-    public function testSend()
-    {
-        $this->exchange->expects($this->once())->method('publish');
-
-        $transport = $this->getTransport();
-        $transport->send($this->message);
-    }
-}
diff --git a/tests/Gelf/Test/Transport/HttpTransportTest.php b/tests/Gelf/Test/Transport/HttpTransportTest.php
index 9c4d561..f9cb760 100644
--- a/tests/Gelf/Test/Transport/HttpTransportTest.php
+++ b/tests/Gelf/Test/Transport/HttpTransportTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -11,58 +12,36 @@
 
 namespace Gelf\Test\Transport;
 
+use Gelf\Encoder\CompressedJsonEncoder;
 use Gelf\Encoder\EncoderInterface;
-use Gelf\Message;
+use Gelf\MessageInterface;
 use Gelf\Transport\HttpTransport;
 use Gelf\Transport\SslOptions;
 use Gelf\Transport\StreamSocketClient;
+use InvalidArgumentException;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use ReflectionObject;
+use RuntimeException;
 
 class HttpTransportTest extends TestCase
 {
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject|StreamSocketClient
-     */
-    protected $socketClient;
-
-    /**
-     * @var StreamSocketClient
-     */
-    protected $originalSocketClient;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject|Message
-     */
-    protected $message;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject|EncoderInterface
-     */
-    protected $encoder;
-
-    /**
-     * @var HttpTransport
-     */
-    protected $transport;
-
-    protected $testMessage;
-
-    public function setUp()
+    private MockObject|StreamSocketClient $socketClient;
+    private MockObject|MessageInterface $message;
+    private MockObject|EncoderInterface $encoder;
+    
+    private HttpTransport $transport;
+    private string $testMessage;
+
+    public function setUp(): void
     {
         $this->testMessage = str_repeat("0123456789", 30); // 300 char string
 
-        $this->socketClient = $this->createMock(
-            "\\Gelf\\Transport\\StreamSocketClient",
-            $methods = array(),
-            $args = array(),
-            $mockClassName = '',
-            $callConstructor = false
-        );
-        $this->message = $this->createMock("\\Gelf\\Message");
+        $this->socketClient = $this->createMock(StreamSocketClient::class);
+        $this->message = $this->createMock(MessageInterface::class);
 
         // create an encoder always return $testMessage
-        $this->encoder = $this->createMock("\\Gelf\\Encoder\\EncoderInterface");
+        $this->encoder = $this->createMock(EncoderInterface::class);
         $this->encoder->expects($this->any())->method('encode')->will(
             $this->returnValue($this->testMessage)
         );
@@ -70,7 +49,7 @@ public function setUp()
         $this->transport = $this->getTransport();
     }
 
-    protected function getTransport()
+    private function getTransport(): HttpTransport
     {
         // initialize transport with an unlimited packet-size
         // and the mocked message encoder
@@ -78,17 +57,16 @@ protected function getTransport()
         $transport->setMessageEncoder($this->encoder);
 
         // replace internal stream socket client with our mock
-        $reflectedTransport = new \ReflectionObject($transport);
+        $reflectedTransport = new ReflectionObject($transport);
         $reflectedClient = $reflectedTransport->getProperty('socketClient');
         $reflectedClient->setAccessible(true);
 
-        $this->originalSocketClient = $reflectedClient->getValue($transport);
         $reflectedClient->setValue($transport, $this->socketClient);
 
         return $transport;
     }
 
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $transport = new HttpTransport();
         $this->validateTransport($transport, '127.0.0.1', 12202, '/gelf');
@@ -103,19 +81,15 @@ public function testConstructor()
         $this->validateTransport($transport, 'localhost', 443, '/gelf', new SslOptions());
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
-    public function testFromUrlConstructorInvalidUri()
+    public function testFromUrlConstructorInvalidUri(): void
     {
+        self::expectException(InvalidArgumentException::class);
         HttpTransport::fromUrl('-://:-');
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
-    public function testFromUrlConstructorInvalidScheme()
+    public function testFromUrlConstructorInvalidScheme(): void
     {
+        self::expectException(InvalidArgumentException::class);
         HttpTransport::fromUrl('ftp://foobar');
     }
 
@@ -155,8 +129,8 @@ public function validateTransport(
         $path,
         $sslOptions = null,
         $authentication = null
-    ) {
-        $r = new \ReflectionObject($transport);
+    ): void {
+        $r = new ReflectionObject($transport);
 
         $testProperties = array(
             'host' => $host,
@@ -169,54 +143,46 @@ public function validateTransport(
         foreach ($testProperties as $property => $value) {
             $p = $r->getProperty($property);
             $p->setAccessible(true);
-            $this->assertEquals($value, $p->getValue($transport));
+            self::assertEquals($value, $p->getValue($transport));
         }
     }
 
-    public function testSslOptionsAreUsed()
+    public function testSslOptionsAreUsed(): void
     {
-        $sslOptions = $this->createMock('\\Gelf\\Transport\\SslOptions');
+        $sslOptions = $this->createMock(SslOptions::class);
         $sslOptions->expects($this->exactly(2))
             ->method('toStreamContext')
             ->will($this->returnValue(array('ssl' => null)));
 
-        $transport = new HttpTransport("localhost", "12345", "/gelf", $sslOptions);
+        $transport = new HttpTransport("localhost", 12345, "/gelf", $sslOptions);
 
-        $reflectedTransport = new \ReflectionObject($transport);
+        $reflectedTransport = new ReflectionObject($transport);
         $reflectedGetContext = $reflectedTransport->getMethod('getContext');
         $reflectedGetContext->setAccessible(true);
         $context = $reflectedGetContext->invoke($transport);
 
-        $this->assertEquals(array('ssl' => null), $context);
+        self::assertEquals(array('ssl' => null), $context);
     }
 
-    public function testSetEncoder()
+    public function testSetEncoder(): void
     {
-        $encoder = $this->createMock('\\Gelf\\Encoder\\EncoderInterface');
+        $encoder = $this->createMock(EncoderInterface::class);
         $this->transport->setMessageEncoder($encoder);
 
-        $this->assertEquals($encoder, $this->transport->getMessageEncoder());
+        self::assertEquals($encoder, $this->transport->getMessageEncoder());
     }
 
-    public function testGetEncoder()
+    public function testEmptyResponseException(): void
     {
-        $transport = new HttpTransport();
-        $this->assertInstanceOf(
-            "\\Gelf\\Encoder\\EncoderInterface",
-            $transport->getMessageEncoder()
+        self::expectException(RuntimeException::class);
+        self::expectExceptionMessage(
+            "Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''"
         );
-    }
 
-    /**
-     * @expectedException        \RuntimeException
-     * @expectedExceptionMessage Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''
-     */
-    public function testEmptyResponseException()
-    {
         $this->transport->send($this->message);
     }
 
-    public function testSendUncompressed()
+    public function testSendUncompressed(): void
     {
         $request = "POST /gelf HTTP/1.1"."\r\n"
                  . "Host: 127.0.0.1:12202"."\r\n"
@@ -224,7 +190,7 @@ public function testSendUncompressed()
                  . "Content-Type: application/json"."\r\n"
                  . "Connection: Keep-Alive"."\r\n"
                  . "Accept: */*"."\r\n"
-                 . ""."\r\n"
+                 . "\r\n"
                  . $this->testMessage;
 
         $this->socketClient
@@ -240,17 +206,19 @@ public function testSendUncompressed()
         $this->transport->send($this->message);
     }
 
-    public function testAuthentication()
+    public function testAuthentication(): void
     {
         $this->transport->setAuthentication("test", "test");
 
-        $test = $this;
         $this->socketClient->expects($this->once())
             ->method("write")
-            ->will($this->returnCallback(function ($data) use ($test) {
-                $test->assertContains("Authorization: Basic " . base64_encode("test:test"), $data);
+            ->will($this->returnCallback(function ($data) {
+                self::assertStringContainsString("Authorization: Basic " . base64_encode("test:test"), $data);
+                return 1;
             }));
-            
+
+
+
         $this->socketClient
             ->expects($this->once())
             ->method("read")
@@ -259,14 +227,13 @@ public function testAuthentication()
         $this->transport->send($this->message);
     }
 
-    public function testProxy()
+    public function testProxy(): void
     {
-        $test = $this;
         $this->socketClient->expects($this->once())
             ->method("setContext")
-            ->willReturnCallback(function (array $context) use ($test) {
-                $test->assertArrayHasKey("http", $context);
-                $test->assertEquals(
+            ->willReturnCallback(function (array $context) {
+                self::assertArrayHasKey("http", $context);
+                self::assertEquals(
                     array(
                         "proxy" => "tcp://proxy.example.com:5100",
                         "request_fulluri" => true
@@ -278,7 +245,7 @@ public function testProxy()
         $this->transport->setProxy("tcp://proxy.example.com:5100", true);
     }
 
-    public function testSendCompressed()
+    public function testSendCompressed(): void
     {
         $request = "POST /gelf HTTP/1.1"."\r\n"
                  . "Host: 127.0.0.1:12202"."\r\n"
@@ -300,7 +267,7 @@ public function testSendCompressed()
             ->method("read")
             ->will($this->returnValue("HTTP/1.1 202 Accepted\r\n\r\n"));
 
-        $compressedEncoder = $this->createMock("\\Gelf\\Encoder\\CompressedJsonEncoder");
+        $compressedEncoder = $this->createMock(CompressedJsonEncoder::class);
         $compressedEncoder
             ->expects($this->any())
             ->method('encode')
@@ -312,25 +279,7 @@ public function testSendCompressed()
         $this->transport->send($this->message);
     }
 
-    public function testPublish()
-    {
-        $transport = $this->getMockBuilder("\\Gelf\\Transport\\HttpTransport")
-            ->setMethods(array("send"))
-            ->disableOriginalConstructor()
-            ->getMock();
-
-        $transport
-            ->expects($this->once())
-            ->method("send")
-            ->with($this->message)
-            ->willReturn(42);
-
-        $response = $transport->publish($this->message);
-
-        $this->assertSame(42, $response);
-    }
-
-    public function testCloseSocketOnHttpOneZero()
+    public function testCloseSocketOnHttpOneZero(): void
     {
         $this->socketClient
             ->expects($this->once())
@@ -344,7 +293,7 @@ public function testCloseSocketOnHttpOneZero()
         $this->transport->send($this->message);
     }
 
-    public function testCloseSocketOnConnectionClose()
+    public function testCloseSocketOnConnectionClose(): void
     {
         $this->socketClient
             ->expects($this->once())
@@ -358,14 +307,14 @@ public function testCloseSocketOnConnectionClose()
         $this->transport->send($this->message);
     }
 
-    public function testConnectTimeout()
+    public function testConnectTimeout(): void
     {
         $this->socketClient
             ->expects($this->once())
             ->method('getConnectTimeout')
             ->will($this->returnValue(123));
 
-        $this->assertEquals(123, $this->transport->getConnectTimeout());
+        self::assertEquals(123, $this->transport->getConnectTimeout());
 
         $this->socketClient
             ->expects($this->once())
diff --git a/tests/Gelf/Test/Transport/IgnoreErrorTransportWrapperTest.php b/tests/Gelf/Test/Transport/IgnoreErrorTransportWrapperTest.php
index ff41b96..4dd5863 100644
--- a/tests/Gelf/Test/Transport/IgnoreErrorTransportWrapperTest.php
+++ b/tests/Gelf/Test/Transport/IgnoreErrorTransportWrapperTest.php
@@ -1,19 +1,21 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Test\Transport;
 
-use Gelf\Message;
-use Gelf\TestCase;
-use Gelf\Transport\AbstractTransport;
+use Gelf\MessageInterface;
 use Gelf\Transport\IgnoreErrorTransportWrapper;
-use \PHPUnit_Framework_MockObject_MockObject as MockObject;
+use Gelf\Transport\TransportInterface;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
 
 class IgnoreErrorTransportWrapperTest extends TestCase
 {
-    public function testSend()
+    public function testSend(): void
     {
         $expectedMessage   = $this->buildMessage();
-        $expectedException = new \RuntimeException();
+        $expectedException = new RuntimeException();
 
         $transport = $this->buildTransport();
         $wrapper   = new IgnoreErrorTransportWrapper($transport);
@@ -26,23 +28,17 @@ public function testSend()
         $bytes = $wrapper->send($expectedMessage);
         $lastError = $wrapper->getLastError();
 
-        $this->assertEquals(0, $bytes);
-        $this->assertSame($expectedException, $lastError);
+        self::assertEquals(0, $bytes);
+        self::assertSame($expectedException, $lastError);
     }
 
-    /**
-     * @return MockObject|AbstractTransport
-     */
-    private function buildTransport()
+    private function buildTransport(): MockObject|TransportInterface
     {
-        return $this->createMock("\\Gelf\\Transport\\AbstractTransport");
+        return $this->createMock(TransportInterface::class);
     }
 
-    /**
-     * @return MockObject|Message
-     */
-    private function buildMessage()
+    private function buildMessage(): MockObject|MessageInterface
     {
-        return $this->createMock("\\Gelf\\Message");
+        return $this->createMock(MessageInterface::class);
     }
 }
diff --git a/tests/Gelf/Test/Transport/KeepAliveRetryTransportWrapperTest.php b/tests/Gelf/Test/Transport/KeepAliveRetryTransportWrapperTest.php
index 2ba8299..b4ed92b 100644
--- a/tests/Gelf/Test/Transport/KeepAliveRetryTransportWrapperTest.php
+++ b/tests/Gelf/Test/Transport/KeepAliveRetryTransportWrapperTest.php
@@ -1,83 +1,67 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Test\Transport;
 
 use Gelf\Message;
-use Gelf\TestCase;
 use Gelf\Transport\HttpTransport;
 use Gelf\Transport\KeepAliveRetryTransportWrapper;
-use PHPUnit_Framework_MockObject_MockObject as MockObject;
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\MockObject\MockObject;
 use RuntimeException;
 
-/**
- * @covers \Gelf\Transport\KeepAliveRetryTransportWrapper
- */
 class KeepAliveRetryTransportWrapperTest extends TestCase
 {
-    /**
-     * @const string
-     */
-    const SUCCESS_VALUE = "HTTP/1.1 202 Accepted\r\n\r\n";
-
-    /**
-     * @var Message
-     */
-    private $message;
-
-    /**
-     * @var HttpTransport|MockObject
-     */
-    private $transport;
-
-    /**
-     * @var KeepAliveRetryTransportWrapper
-     */
-    private $wrapper;
-
-    public function setUp()
+    private const FAILURE_MESSAGE
+        = "Graylog-Server didn't answer properly, expected 'HTTP/1.x 202 Accepted', response is ''";
+
+    private Message $message;
+    private HttpTransport|MockObject $transport;
+    private KeepAliveRetryTransportWrapper $wrapper;
+
+    public function setUp(): void
     {
         $this->message = new Message();
-        $this->transport = $this->buildTransport();
+        $this->transport = $this->createMock(HttpTransport::class);
         $this->wrapper   = new KeepAliveRetryTransportWrapper($this->transport);
     }
 
-    public function testSendSuccess()
+    public function testSendSuccess(): void
     {
         $this->transport->expects($this->once())
             ->method('send')
             ->with($this->message)
-            ->will($this->returnValue(self::SUCCESS_VALUE));
+            ->will($this->returnValue(42));
 
         $bytes = $this->wrapper->send($this->message);
 
-        $this->assertEquals(self::SUCCESS_VALUE, $bytes);
+        self::assertEquals(42, $bytes);
     }
 
-    public function testSendSuccessAfterRetry()
+    public function testSendSuccessAfterRetry(): void
     {
-        $expectedException = new RuntimeException(KeepAliveRetryTransportWrapper::NO_RESPONSE);
+        $expectedException = new RuntimeException(self::FAILURE_MESSAGE);
 
         $this->transport->expects($this->exactly(2))
             ->method('send')
             ->with($this->message)
             ->will($this->onConsecutiveCalls(
                 $this->throwException($expectedException),
-                $this->returnValue(self::SUCCESS_VALUE)
+                42
             ));
 
         $bytes = $this->wrapper->send($this->message);
 
-        $this->assertEquals(self::SUCCESS_VALUE, $bytes);
+        self::assertEquals(42, $bytes);
     }
 
-    /**
-     * @expectedException RuntimeException
-     * @expectedExceptionMessage response is ''
-     */
-    public function testSendFailTwiceWithoutResponse()
+    public function testSendFailTwiceWithoutResponse(): void
     {
-        $expectedException1 = new RuntimeException(KeepAliveRetryTransportWrapper::NO_RESPONSE);
-        $expectedException2 = new RuntimeException(KeepAliveRetryTransportWrapper::NO_RESPONSE);
+        self::expectException(RuntimeException::class);
+        self::expectExceptionMessage("response is ''");
+
+        $expectedException1 = new RuntimeException(self::FAILURE_MESSAGE);
+        $expectedException2 = new RuntimeException(self::FAILURE_MESSAGE);
 
         $this->transport->expects($this->exactly(2))
             ->method('send')
@@ -90,12 +74,11 @@ public function testSendFailTwiceWithoutResponse()
         $this->wrapper->send($this->message);
     }
 
-    /**
-     * @expectedException RuntimeException
-     * @expectedExceptionMessage foo
-     */
-    public function testSendFailWithUnmanagedException()
+    public function testSendFailWithUnmanagedException(): void
     {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage("foo");
+
         $expectedException = new RuntimeException('foo');
 
         $this->transport->expects($this->once())
@@ -105,12 +88,4 @@ public function testSendFailWithUnmanagedException()
 
         $this->wrapper->send($this->message);
     }
-
-    /**
-     * @return MockObject|HttpTransport
-     */
-    private function buildTransport()
-    {
-        return $this->createMock("\\Gelf\\Transport\\HttpTransport");
-    }
 }
diff --git a/tests/Gelf/Test/Transport/RetryTransportWrapperTest.php b/tests/Gelf/Test/Transport/RetryTransportWrapperTest.php
index bf37596..be95099 100644
--- a/tests/Gelf/Test/Transport/RetryTransportWrapperTest.php
+++ b/tests/Gelf/Test/Transport/RetryTransportWrapperTest.php
@@ -1,44 +1,37 @@
 <?php
+declare(strict_types=1);
 
 namespace Gelf\Test\Transport;
 
 use Gelf\Message;
-use Gelf\TestCase;
-use Gelf\Transport\AbstractTransport;
 use Gelf\Transport\RetryTransportWrapper;
+use Gelf\Transport\TransportInterface;
 use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
 use RuntimeException;
 
 class RetryTransportWrapperTest extends TestCase
 {
-    /**
-     * @var Message
-     */
-    private $message;
+    private Message $message;
+    private TransportInterface|MockObject $transport;
 
-    /**
-     * @var AbstractTransport|MockObject
-     */
-    private $transport;
-
-    public function setUp()
+    public function setUp(): void
     {
         $this->message = new Message();
-        $this->transport = $this->buildTransport();
+        $this->transport = $this->createMock(TransportInterface::class);
     }
 
-    public function testGetTransport()
+    public function testGetTransport(): void
     {
         $wrapper = new RetryTransportWrapper($this->transport, 1, null);
-        $this->assertEquals($this->transport, $wrapper->getTransport());
+        self::assertEquals($this->transport, $wrapper->getTransport());
     }
 
-    /**
-     * @expectedException RuntimeException
-     * @expectedExceptionMessage bar
-     */
-    public function testWithoutMatcher()
+    public function testWithoutMatcher(): void
     {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage("bar");
+
         $wrapper = new RetryTransportWrapper($this->transport, 1, null);
 
         $expectedException1 = new RuntimeException('foo');
@@ -54,18 +47,15 @@ public function testWithoutMatcher()
 
         $bytes = $wrapper->send($this->message);
 
-        $this->assertEquals('', $bytes);
+        self::assertEquals('', $bytes);
     }
 
-    /**
-     * @expectedException RuntimeException
-     * @expectedExceptionMessage bar
-     */
-    public function testWithMatcher()
+    public function testWithMatcher(): void
     {
-        $wrapper = new RetryTransportWrapper($this->transport, 1, function (RuntimeException $e) {
-            return true;
-        });
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage("bar");
+
+        $wrapper = new RetryTransportWrapper($this->transport, 1);
 
         $expectedException1 = new RuntimeException('foo');
         $expectedException2 = new RuntimeException('bar');
@@ -80,18 +70,14 @@ public function testWithMatcher()
 
         $bytes = $wrapper->send($this->message);
 
-        $this->assertEquals('', $bytes);
+        self::assertEquals('', $bytes);
     }
-    
-    /**
-     * @expectedException RuntimeException
-     * @expectedExceptionMessage foo
-     */
-    public function testWithFalseMatcher()
+
+    public function testWithFalseMatcher(): void
     {
-        $wrapper = new RetryTransportWrapper($this->transport, 1, function (RuntimeException $e) {
-            return false;
-        });
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage("foo");
+        $wrapper = new RetryTransportWrapper($this->transport, 1, fn () => false);
 
         $expectedException1 = new RuntimeException('foo');
 
@@ -102,14 +88,6 @@ public function testWithFalseMatcher()
 
         $bytes = $wrapper->send($this->message);
 
-        $this->assertEquals('', $bytes);
-    }
-
-    /**
-     * @return MockObject|AbstractTransport
-     */
-    private function buildTransport()
-    {
-        return $this->createMock("\\Gelf\\Transport\\AbstractTransport");
+        self::assertEquals('', $bytes);
     }
 }
diff --git a/tests/Gelf/Test/Transport/SslOptionsTest.php b/tests/Gelf/Test/Transport/SslOptionsTest.php
index f5344f7..512b984 100644
--- a/tests/Gelf/Test/Transport/SslOptionsTest.php
+++ b/tests/Gelf/Test/Transport/SslOptionsTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -11,20 +12,20 @@
 
 namespace Gelf\Test\Transport;
 
-use Gelf\TestCase;
 use Gelf\Transport\SslOptions;
+use PHPUnit\Framework\TestCase;
 
 class SslOptionsTest extends TestCase
 {
-    public function testState()
+    public function testState(): void
     {
         $options = new SslOptions();
 
         // test sane defaults
-        $this->assertTrue($options->getVerifyPeer());
-        $this->assertFalse($options->getAllowSelfSigned());
-        $this->assertNull($options->getCaFile());
-        $this->assertNull($options->getCiphers());
+        self::assertTrue($options->getVerifyPeer());
+        self::assertFalse($options->getAllowSelfSigned());
+        self::assertNull($options->getCaFile());
+        self::assertNull($options->getCiphers());
 
         // test setters
         $options->setVerifyPeer(false);
@@ -32,49 +33,49 @@ public function testState()
         $options->setCaFile('/path/to/ca');
         $options->setCiphers('ALL:!ADH:@STRENGTH');
 
-        $this->assertFalse($options->getVerifyPeer());
-        $this->assertTrue($options->getAllowSelfSigned());
-        $this->assertEquals('/path/to/ca', $options->getCaFile());
-        $this->assertEquals('ALL:!ADH:@STRENGTH', $options->getCiphers());
+        self::assertFalse($options->getVerifyPeer());
+        self::assertTrue($options->getAllowSelfSigned());
+        self::assertEquals('/path/to/ca', $options->getCaFile());
+        self::assertEquals('ALL:!ADH:@STRENGTH', $options->getCiphers());
     }
 
-    public function testToStreamContext()
+    public function testToStreamContext(): void
     {
         $options = new SslOptions();
 
-        $this->assertEquals(array(
-            'ssl' => array(
+        self::assertEquals([
+            'ssl' => [
                 'verify_peer' => true,
                 'allow_self_signed' => false,
-            )
-        ), $options->toStreamContext());
+            ]
+        ], $options->toStreamContext());
 
         $options->setVerifyPeer(false);
         $options->setAllowSelfSigned(true);
         $options->setCaFile('/path/to/ca');
         $options->setCiphers('ALL:!ADH:@STRENGTH');
 
-        $this->assertEquals(array(
-            'ssl' => array(
+        self::assertEquals([
+            'ssl' => [
                 'verify_peer' => false,
                 'allow_self_signed' => true,
                 'cafile' => '/path/to/ca',
                 'ciphers' => 'ALL:!ADH:@STRENGTH'
-            )
-        ), $options->toStreamContext());
+            ]
+        ], $options->toStreamContext());
 
         $options->setCaFile(null);
         $options->setCiphers(null);
 
-        $this->assertEquals(array(
-            'ssl' => array(
+        self::assertEquals([
+            'ssl' => [
                 'verify_peer' => false,
                 'allow_self_signed' => true,
-            )
-        ), $options->toStreamContext());
+            ]
+        ], $options->toStreamContext());
     }
 
-    public function testToStreamContextWithHostname()
+    public function testToStreamContextWithHostname(): void
     {
         $options = new SslOptions();
         $peerNameKey = PHP_VERSION_ID < 50600 ? 'CN_match' : 'peer_name';
@@ -84,25 +85,25 @@ public function testToStreamContextWithHostname()
         $options->setVerifyPeer(false);
         $context = $options->toStreamContext($host);
 
-        $this->assertArrayHasKey('ssl', $context);
-        $this->assertArrayHasKey('SNI_enabled', $context['ssl']);
-        $this->assertArrayNotHasKey('CN_match', $context['ssl']);
-        $this->assertArrayHasKey($sniPeerNameKey, $context['ssl']);
+        self::assertArrayHasKey('ssl', $context);
+        self::assertArrayHasKey('SNI_enabled', $context['ssl']);
+        self::assertArrayNotHasKey('CN_match', $context['ssl']);
+        self::assertArrayHasKey($sniPeerNameKey, $context['ssl']);
 
-        $this->assertEquals(true, $context['ssl']['SNI_enabled']);
-        $this->assertEquals($host, $context['ssl'][$sniPeerNameKey]);
+        self::assertEquals(true, $context['ssl']['SNI_enabled']);
+        self::assertEquals($host, $context['ssl'][$sniPeerNameKey]);
 
 
         $options->setVerifyPeer(true);
         $context = $options->toStreamContext($host);
 
-        $this->assertArrayHasKey('ssl', $context);
-        $this->assertArrayHasKey('SNI_enabled', $context['ssl']);
-        $this->assertArrayHasKey($peerNameKey, $context['ssl']);
-        $this->assertArrayHasKey($sniPeerNameKey, $context['ssl']);
+        self::assertArrayHasKey('ssl', $context);
+        self::assertArrayHasKey('SNI_enabled', $context['ssl']);
+        self::assertArrayHasKey($peerNameKey, $context['ssl']);
+        self::assertArrayHasKey($sniPeerNameKey, $context['ssl']);
 
-        $this->assertEquals(true, $context['ssl']['SNI_enabled']);
-        $this->assertEquals($host, $context['ssl'][$peerNameKey]);
-        $this->assertEquals($host, $context['ssl'][$sniPeerNameKey]);
+        self::assertEquals(true, $context['ssl']['SNI_enabled']);
+        self::assertEquals($host, $context['ssl'][$peerNameKey]);
+        self::assertEquals($host, $context['ssl'][$sniPeerNameKey]);
     }
 }
diff --git a/tests/Gelf/Test/Transport/StreamSocketClientTcpTest.php b/tests/Gelf/Test/Transport/StreamSocketClientTcpTest.php
index 636f9e5..19d0d1a 100644
--- a/tests/Gelf/Test/Transport/StreamSocketClientTcpTest.php
+++ b/tests/Gelf/Test/Transport/StreamSocketClientTcpTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -12,49 +13,39 @@
 namespace Gelf\Test\Transport;
 
 use Gelf\Transport\StreamSocketClient;
-use Gelf\TestCase;
+use LogicException;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
 
 class StreamSocketClientTcpTest extends TestCase
 {
+    private StreamSocketClient $socketClient;
+    private mixed $serverSocket;
 
-    /**
-     * @var StreamSocketClient
-     */
-    protected $socketClient;
+    private string $host = "127.0.0.1";
+    private int $port;
 
-    /**
-     * @var resource
-     */
-    protected $serverSocket;
-
-    protected $host = "127.0.0.1";
-    protected $port;
-
-    public function setUp()
+    public function setUp(): void
     {
         $host = $this->host;
-        $this->serverSocket = stream_socket_server(
-            "tcp://$host:0",
-            $errNo,
-            $errMsg
-        );
+        $this->serverSocket = stream_socket_server("tcp://$host:0");
 
         if (!$this->serverSocket) {
-            throw new \RuntimeException("Failed to create test-server-socket");
+            throw new RuntimeException("Failed to create test-server-socket");
         }
 
         // get random port
         $socketName = stream_socket_get_name(
             $this->serverSocket,
-            $peerName = false
+            remote: false
         );
-        list(, $port) = explode(":", $socketName);
+        [, $port] = explode(":", $socketName);
 
-        $this->socketClient = new StreamSocketClient('tcp', $host, $port);
-        $this->port = $port;
+        $this->socketClient = new StreamSocketClient('tcp', $host, (int)$port);
+        $this->port = (int)$port;
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->socketClient);
         if ($this->serverSocket !== null) {
@@ -63,37 +54,36 @@ public function tearDown()
         }
     }
 
-    public function testGetSocket()
+    public function testGetSocket(): void
     {
-        $this->assertInternalType('resource', $this->socketClient->getSocket());
+        self::assertIsResource($this->socketClient->getSocket());
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $testData = "Hello World!";
         $numBytes = $this->socketClient->write($testData);
 
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         // check that message is sent to server
         $connection = stream_socket_accept($this->serverSocket);
         $readData = fread($connection, $numBytes);
 
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
     }
 
-    /**
-     * @expectedException \RuntimeException
-     */
-    public function testBadWrite()
+    public function testBadWrite(): void
     {
+        self::expectException(RuntimeException::class);
+
         $this->socketClient->write("Hello ");
         fclose($this->serverSocket);
         $this->serverSocket = null;
         $this->socketClient->write("world!");
     }
 
-    public function testMultiWrite()
+    public function testMultiWrite(): void
     {
         // lower timeout for server-socket
         stream_set_timeout($this->serverSocket, 0, 100);
@@ -103,33 +93,33 @@ public function testMultiWrite()
         $testData = "First thing in the morning should be to check,";
 
         $numBytes = $this->socketClient->write($testData);
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         // open connection on server-socket
         $serverConnection = stream_socket_accept($this->serverSocket);
 
         $readData = fread($serverConnection, $numBytes);
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
 
         // -- second write
 
         $testData = "if we can write multiple times on the same socket";
 
         $numBytes = $this->socketClient->write($testData);
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         $readData = fread($serverConnection, $numBytes);
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
 
         fclose($serverConnection);
     }
 
-    public function testRead()
+    public function testRead(): void
     {
         $testData = "Hello Reader :)";
 
         $numBytes = $this->socketClient->write($testData);
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         // lower timeout for server-socket
         stream_set_timeout($this->serverSocket, 0, 100);
@@ -142,15 +132,15 @@ public function testRead()
         fclose($connection);
         $readData = $this->socketClient->read($numBytes);
 
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
     }
 
-    public function testReadContents()
+    public function testReadContents(): void
     {
         $testData = str_repeat("0123456789", mt_rand(1, 10));
 
         $numBytes = $this->socketClient->write($testData);
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         // lower timeout for server-socket
         stream_set_timeout($this->serverSocket, 0, 100);
@@ -164,64 +154,54 @@ public function testReadContents()
 
         $readData = $this->socketClient->read(1024);
 
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
     }
 
-    public function testCloseWithoutConnectionWrite()
+    public function testCloseWithoutConnectionWrite(): void
     {
         // close unopened stream
         $this->socketClient->close();
-        $this->assertTrue($this->socketClient->isClosed());
+        self::assertTrue($this->socketClient->isClosed());
 
         $this->socketClient->write("abcd");
-        $this->assertFalse($this->socketClient->isClosed());
+        self::assertFalse($this->socketClient->isClosed());
         $client = stream_socket_accept($this->serverSocket);
-        $this->assertEquals("abcd", fread($client, 4));
+        self::assertEquals("abcd", fread($client, 4));
     }
 
-    public function testCloseWrite()
+    public function testCloseWrite(): void
     {
         $this->socketClient->write("abcd");
-        $this->assertFalse($this->socketClient->isClosed());
+        self::assertFalse($this->socketClient->isClosed());
         $client = stream_socket_accept($this->serverSocket);
-        $this->assertEquals("abcd", fread($client, 4));
+        self::assertEquals("abcd", fread($client, 4));
 
         $this->socketClient->close();
-        $this->assertTrue($this->socketClient->isClosed());
+        self::assertTrue($this->socketClient->isClosed());
 
         $this->socketClient->write("efgh");
         $client2 = stream_socket_accept($this->serverSocket);
-        $this->assertEquals("efgh", fread($client2, 4));
+        self::assertEquals("efgh", fread($client2, 4));
     }
 
-    /**
-     * @group hhvm-failures
-     */
-    public function testStreamContext()
+    public function testStreamContext(): void
     {
-        $this->failsOnHHVM();
-
         $testName = '127.0.0.1:12345';
-        $context = array(
-            'socket' => array(
+        $context = [
+            'socket' => [
                 'bindto' => $testName
-            )
-        );
+            ]
+        ];
 
         $client = new StreamSocketClient("tcp", $this->host, $this->port, $context);
-        $this->assertEquals($context, $client->getContext());
+        self::assertEquals($context, $client->getContext());
 
-        $this->assertEquals($testName, stream_socket_get_name($client->getSocket(), false));
-        $this->assertNotEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
+        self::assertEquals($testName, stream_socket_get_name($client->getSocket(), false));
+        self::assertNotEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
     }
 
-    /**
-     * @group hhvm-failures
-     */
-    public function testUpdateStreamContext()
+    public function testUpdateStreamContext(): void
     {
-        $this->failsOnHHVM();
-
         $testName = '127.0.0.1:12345';
         $context = array(
             'socket' => array(
@@ -229,32 +209,28 @@ public function testUpdateStreamContext()
             )
         );
 
-        $this->assertEquals(array(), $this->socketClient->getContext());
-        $this->assertNotEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
+        self::assertEquals(array(), $this->socketClient->getContext());
+        self::assertNotEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
         $this->socketClient->close();
 
         $this->socketClient->setContext($context);
-        $this->assertEquals($context, $this->socketClient->getContext());
+        self::assertEquals($context, $this->socketClient->getContext());
 
-        $this->assertEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
+        self::assertEquals($testName, stream_socket_get_name($this->socketClient->getSocket(), false));
     }
 
-    /**
-     * @expectedException \LogicException
-     */
-    public function testSetContextFailsAfterConnect()
+    public function testSetContextFailsAfterConnect(): void
     {
+        self::expectException(LogicException::class);
         // enforce connect
         $this->socketClient->getSocket();
 
         $this->socketClient->setContext(array("foo" => "bar"));
     }
 
-    /**
-     * @expectedException \LogicException
-     */
-    public function testSetConnectTimeoutFailsAfterConnect()
+    public function testSetConnectTimeoutFailsAfterConnect(): void
     {
+        self::expectException(LogicException::class);
         // enforce connect
         $this->socketClient->getSocket();
 
@@ -263,8 +239,7 @@ public function testSetConnectTimeoutFailsAfterConnect()
 
     public function testConnectTimeout()
     {
-        $this->assertEquals(StreamSocketClient::SOCKET_TIMEOUT, $this->socketClient->getConnectTimeout());
         $this->socketClient->setConnectTimeout(1);
-        $this->assertEquals(1, $this->socketClient->getConnectTimeout());
+        self::assertEquals(1, $this->socketClient->getConnectTimeout());
     }
 }
diff --git a/tests/Gelf/Test/Transport/StreamSocketClientUdpTest.php b/tests/Gelf/Test/Transport/StreamSocketClientUdpTest.php
index 0824085..ac56fda 100644
--- a/tests/Gelf/Test/Transport/StreamSocketClientUdpTest.php
+++ b/tests/Gelf/Test/Transport/StreamSocketClientUdpTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -12,29 +13,22 @@
 namespace Gelf\Test\Transport;
 
 use Gelf\Transport\StreamSocketClient;
-use Gelf\TestCase;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
 
 class StreamSocketClientUdpTest extends TestCase
 {
+    private StreamSocketClient $socketClient;
+    private mixed $serverSocket;
 
-    /**
-     * @var StreamSocketClient
-     */
-    protected $socketClient;
-
-    /**
-     * @var resource
-     */
-    protected $serverSocket;
-
-    public function setUp()
+    public function setUp(): void
     {
         $host = "127.0.0.1";
         $this->serverSocket = stream_socket_server(
             "udp://$host:0",
             $errNo,
             $errMsg,
-            $flags = STREAM_SERVER_BIND
+            flags: STREAM_SERVER_BIND
         );
 
         if (!$this->serverSocket) {
@@ -44,43 +38,42 @@ public function setUp()
         // get random port
         $socketName = stream_socket_get_name(
             $this->serverSocket,
-            $peerName = false
+            remote: false
         );
-        list(, $port) = explode(":", $socketName);
+        [, $port] = explode(":", $socketName);
 
-        $this->socketClient = new StreamSocketClient('udp', $host, $port);
+        $this->socketClient = new StreamSocketClient('udp', $host, (int)$port);
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         unset($this->socketClient);
         fclose($this->serverSocket);
     }
 
-    /**
-     * @expectedException RuntimeException
-     */
-    public function testInvalidConstructorArguments()
+    public function testInvalidConstructorArguments(): void
     {
+        self::expectException(RuntimeException::class);
+
         $client = new StreamSocketClient("not-a-scheme", "not-a-host", -1);
         $client->getSocket();
     }
 
-    public function testGetSocket()
+    public function testGetSocket(): void
     {
-        $this->assertInternalType('resource', $this->socketClient->getSocket());
+        self::assertIsResource($this->socketClient->getSocket());
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $testData = "Hello World!";
         $numBytes = $this->socketClient->write($testData);
 
-        $this->assertEquals(strlen($testData), $numBytes);
+        self::assertEquals(strlen($testData), $numBytes);
 
         // check that message is sent to server
         $readData = fread($this->serverSocket, $numBytes);
 
-        $this->assertEquals($testData, $readData);
+        self::assertEquals($testData, $readData);
     }
 }
diff --git a/tests/Gelf/Test/Transport/TcpTransportTest.php b/tests/Gelf/Test/Transport/TcpTransportTest.php
index 4648610..57a85e8 100644
--- a/tests/Gelf/Test/Transport/TcpTransportTest.php
+++ b/tests/Gelf/Test/Transport/TcpTransportTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -12,47 +13,37 @@
 namespace Gelf\Test\Transport;
 
 use Gelf\Encoder\CompressedJsonEncoder;
+use Gelf\Encoder\EncoderInterface;
 use Gelf\Encoder\JsonEncoder;
+use Gelf\Encoder\NoNullByteEncoderInterface;
+use Gelf\MessageInterface;
+use Gelf\Transport\StreamSocketClient;
 use Gelf\Transport\TcpTransport;
 use Gelf\Transport\SslOptions;
+use InvalidArgumentException;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use ReflectionObject;
 
 class TcpTransportTest extends TestCase
 {
+    private MockObject|StreamSocketClient $socketClient;
+    private MockObject|MessageInterface $message;
+    private MockObject|EncoderInterface $encoder;
+    private TcpTransport $transport;
+    private string $testMessage;
 
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $socketClient;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $message;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $encoder;
-
-    /**
-     * @var TcpTransport
-     */
-    protected $transport;
-
-    protected $testMessage;
-
-    public function setUp()
+    public function setUp(): void
     {
         $this->testMessage = str_repeat("0123456789", 30); // 300 char string
 
-        $this->socketClient = $this->getMockBuilder("\\Gelf\\Transport\\StreamSocketClient")
+        $this->socketClient = $this->getMockBuilder(StreamSocketClient::class)
                 ->disableOriginalConstructor()
                 ->getMock();
-        $this->message = $this->createMock("\\Gelf\\Message");
+        $this->message = $this->createMock(MessageInterface::class);
 
         // create an encoder always return $testMessage
-        $this->encoder = $this->createMock("\\Gelf\\Encoder\\NoNullByteEncoderInterface");
+        $this->encoder = $this->createMock(NoNullByteEncoderInterface::class);
         $this->encoder->expects($this->any())->method('encode')->will(
             $this->returnValue($this->testMessage)
         );
@@ -60,15 +51,15 @@ public function setUp()
         $this->transport = $this->getTransport();
     }
 
-    protected function getTransport()
+    private function getTransport(): TcpTransport
     {
         // initialize transport with an unlimited packet-size
         // and the mocked message encoder
-        $transport = new TcpTransport(null, null);
+        $transport = new TcpTransport("", 0);
         $transport->setMessageEncoder($this->encoder);
 
         // replace internal stream socket client with our mock
-        $reflectedTransport = new \ReflectionObject($transport);
+        $reflectedTransport = new ReflectionObject($transport);
         $reflectedClient = $reflectedTransport->getProperty('socketClient');
         $reflectedClient->setAccessible(true);
         $reflectedClient->setValue($transport, $this->socketClient);
@@ -76,7 +67,7 @@ protected function getTransport()
         return $transport;
     }
 
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $transport = new TcpTransport();
         $this->validateTransport($transport, '127.0.0.1', 12201);
@@ -95,51 +86,42 @@ public function validateTransport(
         $host,
         $port,
         $sslOptions = null
-    ) {
-        $r = new \ReflectionObject($transport);
+    ): void {
+        $r = new ReflectionObject($transport);
 
-        foreach (array('host', 'port', 'sslOptions') as $test) {
+        foreach (['host' => $host, 'port' => $port, 'sslOptions' => $sslOptions] as $test => $value) {
             $p = $r->getProperty($test);
             $p->setAccessible(true);
-            $this->assertEquals(${$test}, $p->getValue($transport));
+            self::assertEquals($value, $p->getValue($transport));
         }
     }
 
-    public function testSslOptionsAreUsed()
+    public function testSslOptionsAreUsed(): void
     {
-        $sslOptions = $this->createMock('\\Gelf\\Transport\\SslOptions');
+        $sslOptions = $this->createMock(SslOptions::class);
         $sslOptions->expects($this->exactly(2))
             ->method('toStreamContext')
-            ->will($this->returnValue(array('ssl' => null)));
+            ->will($this->returnValue(['ssl' => null]));
 
-        $transport = new TcpTransport("localhost", "12202", $sslOptions);
+        $transport = new TcpTransport("localhost", 12202, $sslOptions);
 
-        $reflectedTransport = new \ReflectionObject($transport);
+        $reflectedTransport = new ReflectionObject($transport);
         $reflectedGetContext = $reflectedTransport->getMethod('getContext');
         $reflectedGetContext->setAccessible(true);
         $context = $reflectedGetContext->invoke($transport);
 
-        $this->assertEquals(array('ssl' => null), $context);
+        self::assertEquals(['ssl' => null], $context);
     }
 
-    public function testSetEncoder()
+    public function testSetEncoder(): void
     {
-        $encoder = $this->createMock('\\Gelf\\Encoder\\NoNullByteEncoderInterface');
+        $encoder = $this->createMock(NoNullByteEncoderInterface::class);
         $this->transport->setMessageEncoder($encoder);
 
-        $this->assertEquals($encoder, $this->transport->getMessageEncoder());
-    }
-
-    public function testGetEncoder()
-    {
-        $transport = new TcpTransport();
-        $this->assertInstanceOf(
-            "\\Gelf\\Encoder\\EncoderInterface",
-            $transport->getMessageEncoder()
-        );
+        self::assertEquals($encoder, $this->transport->getMessageEncoder());
     }
 
-    public function testSend()
+    public function testSend(): void
     {
         $this->socketClient
             ->expects($this->once())
@@ -151,14 +133,14 @@ public function testSend()
         $this->transport->send($this->message);
     }
 
-    public function testConnectTimeout()
+    public function testConnectTimeout(): void
     {
         $this->socketClient
             ->expects($this->once())
             ->method('getConnectTimeout')
             ->will($this->returnValue(123));
 
-        $this->assertEquals(123, $this->transport->getConnectTimeout());
+        self::assertEquals(123, $this->transport->getConnectTimeout());
 
         $this->socketClient
             ->expects($this->once())
@@ -168,26 +150,21 @@ public function testConnectTimeout()
         $this->transport->setConnectTimeout(123);
     }
 
-    public function testNonNullSafeEncoderFails()
+    public function testNonNullSafeEncoderFails(): void
     {
-        $this->expectException('InvalidArgumentException');
+        self::expectException(InvalidArgumentException::class);
         $this->transport->setMessageEncoder(new CompressedJsonEncoder());
     }
 
-    public function testSafeEncoderSucceeds()
+    public function testSafeEncoderSucceeds(): void
     {
-        $this->assertInstanceOf(
-            "Gelf\Encoder\NoNullByteEncoderInterface",
-            $this->transport->getMessageEncoder()
-        );
-
         $encoder = new JsonEncoder();
-        $this->assertInstanceOf(
-            "Gelf\Encoder\NoNullByteEncoderInterface",
+        self::assertInstanceOf(
+            NoNullByteEncoderInterface::class,
             $encoder
         );
 
         $this->transport->setMessageEncoder($encoder);
-        $this->assertEquals($encoder, $this->transport->getMessageEncoder());
+        self::assertEquals($encoder, $this->transport->getMessageEncoder());
     }
 }
diff --git a/tests/Gelf/Test/Transport/UdpTransportTest.php b/tests/Gelf/Test/Transport/UdpTransportTest.php
index 97caefb..0bba39b 100644
--- a/tests/Gelf/Test/Transport/UdpTransportTest.php
+++ b/tests/Gelf/Test/Transport/UdpTransportTest.php
@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 
 /*
  * This file is part of the php-gelf package.
@@ -11,49 +12,34 @@
 
 namespace Gelf\Test\Transport;
 
+use Gelf\Encoder\EncoderInterface;
+use Gelf\MessageInterface;
+use Gelf\Transport\StreamSocketClient;
 use Gelf\Transport\UdpTransport;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use ReflectionObject;
+use RuntimeException;
 
 class UdpTransportTest extends TestCase
 {
+    private const CHUNK_HEADER_LENGTH = 12;
 
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $socketClient;
+    private MockObject|StreamSocketClient $socketClient;
+    private MockObject|MessageInterface $message;
+    private MockObject|EncoderInterface $encoder;
+    private UdpTransport $transport;
+    private string $testMessage;
 
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $message;
-
-    /**
-     * @var \PHPUnit_Framework_MockObject_MockObject
-     */
-    protected $encoder;
-
-    /**
-     * @var UdpTransport
-     */
-    protected $transport;
-
-    protected $testMessage;
-
-    public function setUp()
+    public function setUp(): void
     {
         $this->testMessage = str_repeat("0123456789", 30); // 300 char string
 
-        $this->socketClient = $this->createMock(
-            "\\Gelf\\Transport\\StreamSocketClient",
-            $methods = array(),
-            $args = array(),
-            $mockClassName = '',
-            $callConstructor = false
-        );
-        $this->message = $this->createMock("\\Gelf\\Message");
+        $this->socketClient = $this->createMock(StreamSocketClient::class);
+        $this->message = $this->createMock(MessageInterface::class);
 
         // create an encoder always return $testMessage
-        $this->encoder = $this->createMock("\\Gelf\\Encoder\\EncoderInterface");
+        $this->encoder = $this->createMock(EncoderInterface::class);
         $this->encoder->expects($this->any())->method('encode')->will(
             $this->returnValue($this->testMessage)
         );
@@ -61,15 +47,15 @@ public function setUp()
         $this->transport = $this->getTransport(0);
     }
 
-    protected function getTransport($chunkSize)
+    private function getTransport(int $chunkSize): UdpTransport
     {
         // initialize transport with an unlimited packet-size
         // and the mocked message encoder
-        $transport = new UdpTransport(null, null, $chunkSize);
+        $transport = new UdpTransport("", 0, $chunkSize);
         $transport->setMessageEncoder($this->encoder);
 
         // replace internal stream socket client with our mock
-        $reflectedTransport = new \ReflectionObject($transport);
+        $reflectedTransport = new ReflectionObject($transport);
         $reflectedClient = $reflectedTransport->getProperty('socketClient');
         $reflectedClient->setAccessible(true);
         $reflectedClient->setValue($transport, $this->socketClient);
@@ -77,24 +63,15 @@ protected function getTransport($chunkSize)
         return $transport;
     }
 
-    public function testSetEncoder()
+    public function testSetEncoder(): void
     {
-        $encoder = $this->createMock('\\Gelf\\Encoder\\EncoderInterface');
+        $encoder = $this->createMock(EncoderInterface::class);
         $this->transport->setMessageEncoder($encoder);
 
-        $this->assertEquals($encoder, $this->transport->getMessageEncoder());
+        self::assertEquals($encoder, $this->transport->getMessageEncoder());
     }
 
-    public function testGetEncoder()
-    {
-        $transport = new UdpTransport();
-        $this->assertInstanceOf(
-            "\\Gelf\\Encoder\\EncoderInterface",
-            $transport->getMessageEncoder()
-        );
-    }
-
-    public function testSendUnchunked()
+    public function testSendUnchunked(): void
     {
         $this->socketClient
             ->expects($this->once())
@@ -104,11 +81,11 @@ public function testSendUnchunked()
         $this->transport->send($this->message);
     }
 
-    public function testSendChunked()
+    public function testSendChunked(): void
     {
-        $chunkSize = 20 + UdpTransport::CHUNK_HEADER_LENGTH;
+        $chunkSize = 20 + self::CHUNK_HEADER_LENGTH;
         $transport = $this->getTransport($chunkSize);
-        $expectedMessageCount =  strlen($this->testMessage) / ($chunkSize - UdpTransport::CHUNK_HEADER_LENGTH);
+        $expectedMessageCount =  strlen($this->testMessage) / ($chunkSize - self::CHUNK_HEADER_LENGTH);
 
         $test = $this;
         $this->socketClient
@@ -116,17 +93,17 @@ public function testSendChunked()
             ->method('write')
             ->willReturnCallback(function ($data) use ($chunkSize, $test) {
                 $test->assertLessThanOrEqual($chunkSize, strlen($data));
+                return 1;
             });
 
         $transport->send($this->message);
     }
 
-    /**
-     * @expectedException \RuntimeException
-     */
     public function testInvalidChunkNumber()
     {
-        $transport = $this->getTransport(UdpTransport::CHUNK_HEADER_LENGTH + 1);
+        self::expectException(RuntimeException::class);
+
+        $transport = $this->getTransport(self::CHUNK_HEADER_LENGTH + 1);
         $transport->send($this->message);
     }
 }
diff --git a/tests/Gelf/TestCase.php b/tests/Gelf/TestCase.php
deleted file mode 100644
index 308331f..0000000
--- a/tests/Gelf/TestCase.php
+++ /dev/null
@@ -1,14 +0,0 @@
-<?php
-
-namespace Gelf;
-
-abstract class TestCase extends \PHPUnit\Framework\TestCase
-{
-
-    public function failsOnHHVM()
-    {
-        if (defined('HHVM_VERSION') && !getenv('FORCE_HHVM_TESTS')) {
-            $this->markTestSkipped("Relies on missing HHVM functionaility");
-        }
-    }
-}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 95ef3ad..c66f272 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -8,5 +8,3 @@
 }
 
 require_once $autoloadFile;
-
-require_once __DIR__ . '/Gelf/TestCase.php';