diff --git a/README.md b/README.md
index 433d696..83a8059 100644
--- a/README.md
+++ b/README.md
@@ -1,14 +1,12 @@
 # Jobby, a PHP cron job manager #
-[![Total Downloads](https://img.shields.io/packagist/dt/hellogerard/jobby.svg)](https://packagist.org/packages/hellogerard/jobby)
-[![Latest Version](https://img.shields.io/packagist/v/hellogerard/jobby.svg)](https://packagist.org/packages/hellogerard/jobby)
-[![Build Status](https://img.shields.io/travis/jobbyphp/jobby.svg)](https://travis-ci.org/jobbyphp/jobby)
-[![MIT License](https://img.shields.io/packagist/l/hellogerard/jobby.svg)](https://github.com/jobbyphp/jobby/blob/master/LICENSE)
+[![Total Downloads](https://img.shields.io/packagist/dt/hatimox/jobby.svg)](https://packagist.org/packages/hatimox/jobby)
+[![Latest Version](https://img.shields.io/packagist/v/hatimox/jobby.svg)](https://packagist.org/packages/hatimox/jobby)
+[![Build Status](https://img.shields.io/travis/hatimox/jobby.svg)](https://travis-ci.org/hatimox/jobby)
+[![MIT License](https://img.shields.io/packagist/l/hatimox/jobby.svg)](https://github.com/hatimox/jobby/blob/master/LICENSE)
 
 Install the master jobby cron job, and it will manage all your offline tasks. Add jobs without modifying crontab.
 Jobby can handle logging, locking, error emails and more.
 
-**NEW REPO:** We have moved `jobby` to a Github org. Please update your remotes to `https://github.com/jobbyphp/jobby.git`.
-
 ## Features ##
 
 - Maintain one master crontab job.
@@ -19,6 +17,13 @@ Jobby can handle logging, locking, error emails and more.
 - Run job as another user, if crontab user has `sudo` privileges.
 - Run only on certain hostnames (handy in webfarms).
 - Theoretical Windows support (but not ever tested)
+- Send alerts to Slack or Mattermost whenever a job exits with an error status.
+
+## Requirements ##
+
+- PHP 8.0 or higher
+- [Composer](http://getcomposer.org)
+- `posix` extension (for Unix/Linux systems)
 
 ## Getting Started ##
 
@@ -26,7 +31,7 @@ Jobby can handle logging, locking, error emails and more.
 
 The recommended way to install Jobby is through [Composer](http://getcomposer.org):
 ```
-$ composer require hellogerard/jobby
+$ composer require hatimox/jobby
 ```
 
 Then add the following line to your (or whomever's) crontab:
@@ -36,7 +41,7 @@ Then add the following line to your (or whomever's) crontab:
 
 After Jobby installs, you can copy an example file to the project root.
 ```
-$ cp vendor/hellogerard/jobby/resources/jobby.php .
+$ cp vendor/hatimox/jobby/resources/jobby.php .
 ```
 
 ### Running a job ###
@@ -208,6 +213,7 @@ dateFormat     | string    | Y-m-d H:i:s                         | Format for da
 _**Mailing**_  |           |                                     | _**Options for emailing errors**_
 recipients     | string    | null                                | Comma-separated string of email addresses
 mailer         | string    | sendmail                            | Email method: _sendmail_ or _smtp_ or _mail_
+mailSubject    | string    | null                                | Email subject
 smtpHost       | string    | null                                | SMTP host, if `mailer` is smtp
 smtpPort       | integer   | 25                                  | SMTP port, if `mailer` is smtp
 smtpUsername   | string    | null                                | SMTP user, if `mailer` is smtp
@@ -215,11 +221,49 @@ smtpPassword   | string    | null                                | SMTP password
 smtpSecurity   | string    | null                                | SMTP security option: _ssl_ or _tls_, if `mailer` is smtp
 smtpSender     | string    | jobby@<hostname>              | The sender and from addresses used in SMTP notices
 smtpSenderName | string    | Jobby                               | The name used in the from field for SMTP messages
+_**Notifications**_  |           |                                     | _**Options for sending Alerts when errors**_
+mattermostUrl  | string    | null                                | The webhook url from Mattermost
+slackChannel   | string    | null                                | The name of Slack Channel (#channel)
+slackUrl       | string    | null                                | The webhook url from Slack
+slackSender    | string    | null                                | The name used in the from field for Slack
 
 ## Symfony integration ##
 
 Symfony bundle for Jobby - [imper86/jobby-cron-bundle](https://github.com/imper86/jobby-cron-bundle)
 
+## Changelog ##
+
+### v3.0.0 (PHP 8+ Upgrade) ###
+
+**Breaking Changes:**
+- Minimum PHP version is now 8.0
+- Replaced SwiftMailer with Symfony Mailer
+- PHPUnit upgraded to ^9.0|^10.0|^11.0
+
+**New Features & Improvements:**
+- Full PHP 8.0+ compatibility with typed properties and return types
+- Uses Symfony Mailer DSN format for mail configuration
+- Modern PHP syntax: union types, match expressions, named arguments support
+- Strict type comparisons throughout the codebase
+
+**Migration Guide:**
+
+If you were injecting a custom mailer, update your code:
+
+```php
+// Before (SwiftMailer)
+$mailer = new \Swift_Mailer($transport);
+$helper = new \Jobby\Helper($mailer);
+
+// After (Symfony Mailer)
+use Symfony\Component\Mailer\Mailer;
+use Symfony\Component\Mailer\Transport;
+
+$transport = Transport::fromDsn('smtp://localhost:25');
+$mailer = new Mailer($transport);
+$helper = new \Jobby\Helper($mailer);
+```
+
 ## Credits ##
 
 Developed before, but since inspired by [whenever](<https://github.com/javan/whenever>).
diff --git a/composer.json b/composer.json
index 326e27b..64960ad 100644
--- a/composer.json
+++ b/composer.json
@@ -1,30 +1,28 @@
 {
-  "name": "hellogerard/jobby",
-  "homepage": "https://github.com/jobbyphp/jobby",
+  "name": "hatimox/jobby",
+  "homepage": "https://github.com/hatimox/jobby",
   "license": "MIT",
   "description": "Manage all your cron jobs without modifying crontab. Handles locking, logging, error emails, and more.",
   "authors": [
     {
-      "name": "Gerard Sychay",
-      "email": "hellogerard@gmail.com",
-      "homepage": "https://github.com/hellogerard"
-    },
-    {
-      "name": "Michael Contento",
-      "homepage": "https://github.com/michaelcontento"
+      "name": "Hatim HAFFANE",
+      "email": "hatim.haffane@gmail.com",
+      "homepage": "https://github.com/hatimox"
     }
   ],
   "require": {
-    "php": ">=5.6",
+    "php": ">=8.0",
+    "alek13/slack": "^2.2",
     "dragonmantank/cron-expression": "^3.0",
+    "guzzlehttp/guzzle": "^7.0",
     "opis/closure": "^3.5",
-    "swiftmailer/swiftmailer": "^5.4|^6.0",
-    "symfony/process": "^2.7|^3.0|^4.0|^5.0"
+    "symfony/mailer": "^5.4|^6.0|^7.0",
+    "symfony/process": "^5.0|^6.0|^7.0"
   },
   "require-dev": {
     "mp091689/dump-die": "^1.0",
-    "phpunit/phpunit": "^4.6",
-    "symfony/filesystem": "^2.7|^3.0|^4.0|^5.0"
+    "phpunit/phpunit": "^9.0|^10.0|^11.0",
+    "symfony/filesystem": "^5.0|^6.0|^7.0"
   },
   "autoload": {
     "psr-4": {
diff --git a/src/BackgroundJob.php b/src/BackgroundJob.php
index c339747..41b6605 100644
--- a/src/BackgroundJob.php
+++ b/src/BackgroundJob.php
@@ -2,36 +2,29 @@
 
 namespace Jobby;
 
-use Opis\Closure\SerializableClosure;
-
 class BackgroundJob
 {
     /**
      * @var Helper
      */
-    protected $helper;
+    protected Helper $helper;
 
     /**
      * @var string
      */
-    protected $job;
+    protected string $job;
 
     /**
      * @var string
      */
-    protected $tmpDir;
+    protected string $tmpDir;
 
     /**
      * @var array
      */
-    protected $config;
+    protected array $config;
 
-    /**
-     * @param string $job
-     * @param array  $config
-     * @param Helper $helper
-     */
-    public function __construct($job, array $config, Helper $helper = null)
+    public function __construct(string $job, array $config, ?Helper $helper = null)
     {
         $this->job = $job;
         $this->config = $config + [
@@ -54,7 +47,11 @@ public function __construct($job, array $config, Helper $helper = null)
             'dateFormat'     => null,
             'enabled'        => null,
             'haltDir'        => null,
-            'debug'          => null,
+            'mattermostUrl'  => null,
+            'slackChannel'   => null,
+            'slackUrl'       => null,
+            'slackSender'    => null,
+            'mailSubject'    => null,
         ];
 
         $this->config['output_stdout'] = $this->config['output_stdout'] === null ? $this->config['output'] : $this->config['output_stdout'];
@@ -65,7 +62,7 @@ public function __construct($job, array $config, Helper $helper = null)
         $this->tmpDir = $this->helper->getTempDir();
     }
 
-    public function run()
+    public function run(): void
     {
         $lockFile = $this->getLockFile();
 
@@ -73,7 +70,7 @@ public function run()
             $this->checkMaxRuntime($lockFile);
         } catch (Exception $e) {
             $this->log('ERROR: ' . $e->getMessage(), 'stderr');
-            $this->mail($e->getMessage());
+            $this->notify($e->getMessage());
 
             return;
         }
@@ -96,7 +93,7 @@ public function run()
             $this->log('INFO: ' . $e->getMessage(), 'stderr');
         } catch (Exception $e) {
             $this->log('ERROR: ' . $e->getMessage(), 'stderr');
-            $this->mail($e->getMessage());
+            $this->notify($e->getMessage());
         }
 
         if ($lockAcquired) {
@@ -104,26 +101,21 @@ public function run()
 
             // remove log file if empty
             $logfile = $this->getLogfile();
-            if (is_file($logfile) && filesize($logfile) <= 0) {
+            if ($logfile !== false && is_file($logfile) && (filesize($logfile) <= 2 || file_get_contents($logfile) === "[]")) {
                 unlink($logfile);
             }
         }
     }
 
-    /**
-     * @return array
-     */
-    public function getConfig()
+    public function getConfig(): array
     {
         return $this->config;
     }
 
     /**
-     * @param string $lockFile
-     *
      * @throws Exception
      */
-    protected function checkMaxRuntime($lockFile)
+    protected function checkMaxRuntime(string $lockFile): void
     {
         $maxRuntime = $this->config['maxRuntime'];
         if ($maxRuntime === null) {
@@ -143,9 +135,9 @@ protected function checkMaxRuntime($lockFile)
     }
 
     /**
-     * @param string $message
+     * @deprecated
      */
-    protected function mail($message)
+    protected function mail(string $message): void
     {
         if (empty($this->config['recipients'])) {
             return;
@@ -158,11 +150,36 @@ protected function mail($message)
         );
     }
 
-    /**
-     * @param string $output
-     * @return string
-     */
-    protected function getLogfile($output = 'stdout')
+    protected function notify(string $message): void
+    {
+        if (!empty($this->config['recipients'])) {
+            $this->helper->sendMail(
+                $this->job,
+                $this->config,
+                $message
+            );
+        }
+
+        if (!empty($this->config['mattermostUrl'])) {
+            $this->helper->sendMattermostAlert(
+                $this->job,
+                $this->config,
+                $message
+            );
+        }
+
+        if (!empty($this->config['slackChannel']) && !empty($this->config['slackUrl'])) {
+            $this->helper->sendSlackAlert(
+                $this->job,
+                $this->config,
+                $message
+            );
+        }
+
+
+    }
+
+    protected function getLogfile(string $output = 'stdout'): string|false
     {
         $logfile = $this->config['output_'.$output];
         if ($logfile === null) {
@@ -178,10 +195,7 @@ protected function getLogfile($output = 'stdout')
         return $logfile;
     }
 
-    /**
-     * @return string
-     */
-    protected function getLockFile()
+    protected function getLockFile(): string
     {
         $tmp = $this->tmpDir;
         $job = $this->helper->escape($this->job);
@@ -195,10 +209,7 @@ protected function getLockFile()
         }
     }
 
-    /**
-     * @return bool
-     */
-    protected function shouldRun()
+    protected function shouldRun(): bool
     {
         if (!$this->config['enabled']) {
             return false;
@@ -211,18 +222,14 @@ protected function shouldRun()
         }
 
         $host = $this->helper->getHost();
-        if (strcasecmp($this->config['runOnHost'], $host) != 0) {
+        if (strcasecmp($this->config['runOnHost'], $host) !== 0) {
             return false;
         }
 
         return true;
     }
 
-    /**
-     * @param string $message
-     * @param string $output
-     */
-    protected function log($message, $output = 'stdout')
+    protected function log(string $message, string $output = 'stdout'): void
     {
         $now = date($this->config['dateFormat'], $_SERVER['REQUEST_TIME']);
 
@@ -231,7 +238,7 @@ protected function log($message, $output = 'stdout')
         }
     }
 
-    protected function runFunction()
+    protected function runFunction(): void
     {
         $command = unserialize($this->config['closure']);
 
@@ -246,7 +253,9 @@ protected function runFunction()
         }
         $content = ob_get_contents();
         if ($logfile = $this->getLogfile()) {
-            file_put_contents($this->getLogfile(), $content, FILE_APPEND);
+            if(strlen($content) > 2){
+                file_put_contents($this->getLogfile(), $content, FILE_APPEND);
+            }
         }
         ob_end_clean();
 
@@ -255,7 +264,7 @@ protected function runFunction()
         }
     }
 
-    protected function runFile()
+    protected function runFile(): void
     {
         // If job should run as another user, we must be on *nix and
         // must have sudo privileges.
diff --git a/src/Helper.php b/src/Helper.php
index 272b4e3..8a3915a 100644
--- a/src/Helper.php
+++ b/src/Helper.php
@@ -1,104 +1,113 @@
 <?php
+
 namespace Jobby;
 
+use GuzzleHttp\Client as Guzzle;
+use Symfony\Component\Mailer\Mailer;
+use Symfony\Component\Mailer\MailerInterface;
+use Symfony\Component\Mailer\Transport;
+use Symfony\Component\Mime\Address;
+use Symfony\Component\Mime\Email;
+
 class Helper
 {
     /**
      * @var int
      */
-    const UNIX = 0;
+    public const UNIX = 0;
 
     /**
      * @var int
      */
-    const WINDOWS = 1;
+    public const WINDOWS = 1;
 
     /**
      * @var resource[]
      */
-    private $lockHandles = [];
+    private array $lockHandles = [];
 
     /**
-     * @var \Swift_Mailer
+     * @var MailerInterface|null
      */
-    private $mailer;
+    private ?MailerInterface $mailer;
 
     /**
-     * @param \Swift_Mailer $mailer
+     * The Guzzle HTTP client instance
      */
-    public function __construct(\Swift_Mailer $mailer = null)
+    protected Guzzle $guzzle;
+
+    public function __construct(?MailerInterface $mailer = null)
     {
         $this->mailer = $mailer;
+        $this->guzzle = new Guzzle();
     }
 
-    /**
-     * @param string $job
-     * @param array  $config
-     * @param string $message
-     *
-     * @return \Swift_Message
-     */
-    public function sendMail($job, array $config, $message)
+    public function sendMail(string $job, array $config, string $message): Email
     {
         $host = $this->getHost();
         $body = <<<EOF
-$message
+        $message
+
+        You can find its output in {$config['output']} on $host.
 
-You can find its output in {$config['output']} on $host.
+        Best,
+        jobby@$host
+        EOF;
 
-Best,
-jobby@$host
-EOF;
-        $mail = new \Swift_Message();
-        $mail->setTo(explode(',', $config['recipients']));
-        $mail->setSubject("[$host] '{$job}' needs some attention!");
-        $mail->setBody($body);
-        $mail->setFrom([$config['smtpSender'] => $config['smtpSenderName']]);
-        $mail->setSender($config['smtpSender']);
+        $email = (new Email())
+            ->from(new Address($config['smtpSender'], $config['smtpSenderName']))
+            ->to(...array_map('trim', explode(',', $config['recipients'])))
+            ->subject(empty($config['mailSubject'])
+                ? "[$host] '{$job}' needs some attention!"
+                : $config['mailSubject'])
+            ->text($body);
 
         $mailer = $this->getCurrentMailer($config);
-        $mailer->send($mail);
+        $mailer->send($email);
 
-        return $mail;
+        return $email;
     }
 
-    /**
-     * @param array $config
-     *
-     * @return \Swift_Mailer
-     */
-    private function getCurrentMailer(array $config)
+    private function getCurrentMailer(array $config): MailerInterface
     {
         if ($this->mailer !== null) {
             return $this->mailer;
         }
 
-        $swiftVersion = (int) explode('.', \Swift::VERSION)[0];
+        $dsn = $this->buildMailerDsn($config);
+        $transport = Transport::fromDsn($dsn);
 
+        return new Mailer($transport);
+    }
+
+    private function buildMailerDsn(array $config): string
+    {
         if ($config['mailer'] === 'smtp') {
-            $transport = new \Swift_SmtpTransport(
-                $config['smtpHost'],
-                $config['smtpPort'],
-                $config['smtpSecurity']
-            );
-            $transport->setUsername($config['smtpUsername']);
-            $transport->setPassword($config['smtpPassword']);
-        } elseif ($swiftVersion < 6 && $config['mailer'] === 'mail') {
-            $transport = \Swift_MailTransport::newInstance();
-        } else {
-            $transport = new \Swift_SendmailTransport();
+            $scheme = match ($config['smtpSecurity']) {
+                'ssl' => 'smtps',
+                'tls' => 'smtp',
+                default => 'smtp',
+            };
+
+            $user = $config['smtpUsername'] ? urlencode($config['smtpUsername']) : '';
+            $pass = $config['smtpPassword'] ? urlencode($config['smtpPassword']) : '';
+            $auth = ($user && $pass) ? "{$user}:{$pass}@" : ($user ? "{$user}@" : '');
+
+            $host = $config['smtpHost'] ?? 'localhost';
+            $port = $config['smtpPort'] ?? 25;
+
+            return "{$scheme}://{$auth}{$host}:{$port}";
         }
 
-        return new \Swift_Mailer($transport);
+        // Default to sendmail
+        return 'sendmail://default';
     }
 
     /**
-     * @param string $lockFile
-     *
      * @throws Exception
      * @throws InfoException
      */
-    public function acquireLock($lockFile)
+    public function acquireLock(string $lockFile): void
     {
         if (array_key_exists($lockFile, $this->lockHandles)) {
             throw new Exception("Lock already acquired (Lockfile: $lockFile).");
@@ -130,11 +139,9 @@ public function acquireLock($lockFile)
     }
 
     /**
-     * @param string $lockFile
-     *
      * @throws Exception
      */
-    public function releaseLock($lockFile)
+    public function releaseLock(string $lockFile): void
     {
         if (!array_key_exists($lockFile, $this->lockHandles)) {
             throw new Exception("Lock NOT held - bug? Lockfile: $lockFile");
@@ -148,12 +155,7 @@ public function releaseLock($lockFile)
         unset($this->lockHandles[$lockFile]);
     }
 
-    /**
-     * @param string $lockFile
-     *
-     * @return int
-     */
-    public function getLockLifetime($lockFile)
+    public function getLockLifetime(string $lockFile): int
     {
         if (!file_exists($lockFile)) {
             return 0;
@@ -170,13 +172,10 @@ public function getLockLifetime($lockFile)
 
         $stat = stat($lockFile);
 
-        return (time() - $stat['mtime']);
+        return time() - $stat['mtime'];
     }
 
-    /**
-     * @return string
-     */
-    public function getTempDir()
+    public function getTempDir(): string
     {
         // @codeCoverageIgnoreStart
         if (function_exists('sys_get_temp_dir')) {
@@ -195,26 +194,17 @@ public function getTempDir()
         return $tmp;
     }
 
-    /**
-     * @return string
-     */
-    public function getHost()
+    public function getHost(): string
     {
         return php_uname('n');
     }
 
-    /**
-     * @return string|null
-     */
-    public function getApplicationEnv()
+    public function getApplicationEnv(): ?string
     {
-        return isset($_SERVER['APPLICATION_ENV']) ? $_SERVER['APPLICATION_ENV'] : null;
+        return $_SERVER['APPLICATION_ENV'] ?? null;
     }
 
-    /**
-     * @return int
-     */
-    public function getPlatform()
+    public function getPlatform(): int
     {
         if (strncasecmp(PHP_OS, 'Win', 3) === 0) {
             // @codeCoverageIgnoreStart
@@ -225,12 +215,7 @@ public function getPlatform()
         return self::UNIX;
     }
 
-    /**
-     * @param string $input
-     *
-     * @return string
-     */
-    public function escape($input)
+    public function escape(string $input): string
     {
         $input = strtolower($input);
         $input = preg_replace('/[^a-z0-9_. -]+/', '', $input);
@@ -241,7 +226,7 @@ public function escape($input)
         return $input;
     }
 
-    public function getSystemNullDevice()
+    public function getSystemNullDevice(): string
     {
         $platform = $this->getPlatform();
         if ($platform === self::UNIX) {
@@ -249,4 +234,39 @@ public function getSystemNullDevice()
         }
         return 'NUL';
     }
+
+    public function sendSlackAlert(string $job, array $config, string $message): void
+    {
+        $host = $this->getHost();
+        $body = <<<EOF
+        $message
+
+        You can find its output in {$config['output']} on $host.
+
+        Best,
+        jobby@$host
+        EOF;
+        $client = new \Maknz\Slack\Client($config['slackUrl']);
+        $client->to($config['slackChannel']);
+        if ($config['slackSender']) {
+            $client->from($config['slackSender']);
+        }
+        $client->send($body);
+    }
+
+    public function sendMattermostAlert(string $job, array $config, string $message): void
+    {
+        $host = $this->getHost();
+        $body = <<<EOF
+        $message
+
+        You can find its output in {$config['output']} on $host.
+
+        Best,
+        jobby@$host
+        EOF;
+        $payload = ['text' => $body];
+        $encoded = json_encode($payload, JSON_UNESCAPED_UNICODE);
+        $this->guzzle->post($config['mattermostUrl'], ['body' => $encoded]);
+    }
 }
diff --git a/src/Jobby.php b/src/Jobby.php
index 821f8c6..b1bb80b 100644
--- a/src/Jobby.php
+++ b/src/Jobby.php
@@ -12,26 +12,23 @@ class Jobby
     /**
      * @var array
      */
-    protected $config = [];
+    protected array $config = [];
 
     /**
      * @var string
      */
-    protected $script;
+    protected string $script;
 
     /**
      * @var array
      */
-    protected $jobs = [];
+    protected array $jobs = [];
 
     /**
-     * @var Helper
+     * @var Helper|null
      */
-    protected $helper;
+    protected ?Helper $helper = null;
 
-    /**
-     * @param array $config
-     */
     public function __construct(array $config = [])
     {
         $this->setConfig($this->getDefaultConfig());
@@ -40,10 +37,7 @@ public function __construct(array $config = [])
         $this->script = realpath(__DIR__ . '/../bin/run-job');
     }
 
-    /**
-     * @return Helper
-     */
-    protected function getHelper()
+    protected function getHelper(): Helper
     {
         if ($this->helper === null) {
             $this->helper = new Helper();
@@ -52,10 +46,7 @@ protected function getHelper()
         return $this->helper;
     }
 
-    /**
-     * @return array
-     */
-    public function getDefaultConfig()
+    public function getDefaultConfig(): array
     {
         return [
             'jobClass'       => 'Jobby\BackgroundJob',
@@ -79,29 +70,25 @@ public function getDefaultConfig()
             'enabled'        => true,
             'haltDir'        => null,
             'debug'          => false,
+            'mattermostUrl'  => null,
+            'slackChannel'   => null,
+            'slackUrl'       => null,
+            'slackSender'    => null,
+            'mailSubject'    => null,
         ];
     }
 
-    /**
-     * @param array
-     */
-    public function setConfig(array $config)
+    public function setConfig(array $config): void
     {
         $this->config = array_merge($this->config, $config);
     }
 
-    /**
-     * @return array
-     */
-    public function getConfig()
+    public function getConfig(): array
     {
         return $this->config;
     }
 
-    /**
-     * @return array
-     */
-    public function getJobs()
+    public function getJobs(): array
     {
         return $this->jobs;
     }
@@ -109,12 +96,9 @@ public function getJobs()
     /**
      * Add a job.
      *
-     * @param string $job
-     * @param array  $config
-     *
      * @throws Exception
      */
-    public function add($job, array $config)
+    public function add(string $job, array $config): void
     {
         if (empty($config['schedule'])) {
             throw new Exception("'schedule' is required for '$job' job");
@@ -145,9 +129,9 @@ public function add($job, array $config)
     /**
      * Run all jobs.
      */
-    public function run()
+    public function run(): void
     {
-        $isUnix = ($this->helper->getPlatform() === Helper::UNIX);
+        $isUnix = ($this->getHelper()->getPlatform() === Helper::UNIX);
 
         if ($isUnix && !extension_loaded('posix')) {
             throw new Exception('posix extension is required');
@@ -155,7 +139,7 @@ public function run()
 
         $scheduleChecker = new ScheduleChecker(new DateTimeImmutable("now"));
         foreach ($this->jobs as $jobConfig) {
-            list($job, $config) = $jobConfig;
+            [$job, $config] = $jobConfig;
             if (!$scheduleChecker->isDue($config['schedule'])) {
                 continue;
             }
@@ -167,11 +151,7 @@ public function run()
         }
     }
 
-    /**
-     * @param string $job
-     * @param array  $config
-     */
-    protected function runUnix($job, array $config)
+    protected function runUnix(string $job, array $config): void
     {
         $command = $this->getExecutableCommand($job, $config);
         $binary = $this->getPhpBinary();
@@ -181,11 +161,7 @@ protected function runUnix($job, array $config)
     }
 
     // @codeCoverageIgnoreStart
-    /**
-     * @param string $job
-     * @param array  $config
-     */
-    protected function runWindows($job, array $config)
+    protected function runWindows(string $job, array $config): void
     {
         // Run in background (non-blocking). From
         // http://us3.php.net/manual/en/function.exec.php#43834
@@ -196,13 +172,7 @@ protected function runWindows($job, array $config)
     }
     // @codeCoverageIgnoreEnd
 
-    /**
-     * @param string $job
-     * @param array  $config
-     *
-     * @return string
-     */
-    protected function getExecutableCommand($job, array $config)
+    protected function getExecutableCommand(string $job, array $config): string
     {
         if (isset($config['closure'])) {
             $wrapper = new SerializableClosure($config['closure']);
@@ -217,10 +187,7 @@ protected function getExecutableCommand($job, array $config)
         return sprintf('"%s" "%s" "%s"', $this->script, $job, http_build_query($config));
     }
 
-    /**
-     * @return false|string
-     */
-    protected function getPhpBinary()
+    protected function getPhpBinary(): string|false
     {
         $executableFinder = new PhpExecutableFinder();
 
diff --git a/src/ScheduleChecker.php b/src/ScheduleChecker.php
index ac4a914..89e5aa3 100644
--- a/src/ScheduleChecker.php
+++ b/src/ScheduleChecker.php
@@ -8,28 +8,24 @@
 class ScheduleChecker
 {
     /**
-     * @var DateTimeImmutable|null
+     * @var DateTimeImmutable
      */
-    private $now;
+    private DateTimeImmutable $now;
 
-    public function __construct(DateTimeImmutable $now = null)
+    public function __construct(?DateTimeImmutable $now = null)
     {
         $this->now = $now instanceof DateTimeImmutable ? $now : new DateTimeImmutable("now");
     }
 
-    /**
-     * @param string|callable $schedule
-     * @return bool
-     */
-    public function isDue($schedule)
+    public function isDue(string|callable $schedule): bool
     {
         if (is_callable($schedule)) {
-            return call_user_func($schedule, $this->now);
+            return $schedule($this->now);
         }
 
         $dateTime = \DateTime::createFromFormat('Y-m-d H:i:s', $schedule);
         if ($dateTime !== false) {
-            return $dateTime->format('Y-m-d H:i') == $this->now->format('Y-m-d H:i');
+            return $dateTime->format('Y-m-d H:i') === $this->now->format('Y-m-d H:i');
         }
 
         return CronExpression::factory((string)$schedule)->isDue($this->now);
diff --git a/tests/BackgroundJobTest.php b/tests/BackgroundJobTest.php
index 4f23482..0dc1fc4 100644
--- a/tests/BackgroundJobTest.php
+++ b/tests/BackgroundJobTest.php
@@ -5,12 +5,13 @@
 use Jobby\BackgroundJob;
 use Jobby\Helper;
 use Opis\Closure\SerializableClosure;
+use PHPUnit\Framework\TestCase;
 use Symfony\Component\Filesystem\Filesystem;
 
 /**
  * @coversDefaultClass Jobby\BackgroundJob
  */
-class BackgroundJobTest extends \PHPUnit_Framework_TestCase
+class BackgroundJobTest extends TestCase
 {
     const JOB_NAME = 'name';
 
@@ -27,7 +28,7 @@ class BackgroundJobTest extends \PHPUnit_Framework_TestCase
     /**
      * {@inheritdoc}
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->logFile = __DIR__ . '/_files/BackgroundJobTest.log';
         if (file_exists($this->logFile)) {
@@ -40,14 +41,14 @@ protected function setUp()
     /**
      * {@inheritdoc}
      */
-    protected function tearDown()
+    protected function tearDown(): void
     {
         if (file_exists($this->logFile)) {
             unlink($this->logFile);
         }
     }
 
-    public function runProvider()
+    public function runProvider(): array
     {
         $echo = function () {
             echo 'test';
@@ -72,10 +73,10 @@ public function runProvider()
     /**
      * @covers ::getConfig
      */
-    public function testGetConfig()
+    public function testGetConfig(): void
     {
         $job = new BackgroundJob('test job',[]);
-        $this->assertInternalType('array',$job->getConfig());
+        $this->assertIsArray($job->getConfig());
     }
 
     /**
@@ -86,7 +87,7 @@ public function testGetConfig()
      * @param array  $config
      * @param string $expectedOutput
      */
-    public function testRun($config, $expectedOutput)
+    public function testRun($config, $expectedOutput): void
     {
         $this->runJob($config);
 
@@ -96,20 +97,20 @@ public function testRun($config, $expectedOutput)
     /**
      * @covers ::runFile
      */
-    public function testInvalidCommand()
+    public function testInvalidCommand(): void
     {
         $this->runJob(['command' => 'invalid-command']);
 
-        $this->assertContains('invalid-command', $this->getLogContent());
+        $this->assertStringContainsString('invalid-command', $this->getLogContent());
 
         if ($this->helper->getPlatform() === Helper::UNIX) {
-            $this->assertContains('not found', $this->getLogContent());
-            $this->assertContains(
+            $this->assertStringContainsString('not found', $this->getLogContent());
+            $this->assertStringContainsString(
                 "ERROR: Job exited with status '127'",
                 $this->getLogContent()
             );
         } else {
-            $this->assertContains(
+            $this->assertStringContainsString(
                 'not recognized as an internal or external command',
                 $this->getLogContent()
             );
@@ -119,7 +120,7 @@ public function testInvalidCommand()
     /**
      * @covers ::runFunction
      */
-    public function testClosureNotReturnTrue()
+    public function testClosureNotReturnTrue(): void
     {
         $this->runJob(
             [
@@ -129,7 +130,7 @@ public function testClosureNotReturnTrue()
             ]
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             'ERROR: Closure did not return true! Returned:',
             $this->getLogContent()
         );
@@ -138,7 +139,7 @@ public function testClosureNotReturnTrue()
     /**
      * @covers ::getLogFile
      */
-    public function testHideStdOutByDefault()
+    public function testHideStdOutByDefault(): void
     {
         ob_start();
         $this->runJob(
@@ -158,7 +159,7 @@ public function testHideStdOutByDefault()
     /**
      * @covers ::getLogFile
      */
-    public function testShouldCreateLogFolder()
+    public function testShouldCreateLogFolder(): void
     {
         $logfile = dirname($this->logFile) . '/foo/bar.log';
         $this->runJob(
@@ -183,7 +184,7 @@ public function testShouldCreateLogFolder()
     /**
      * @covers ::getLogFile
      */
-    public function testShouldSplitStderrAndStdout()
+    public function testShouldSplitStderrAndStdout(): void
     {
         $dirname = dirname($this->logFile);
         $stdout = $dirname . '/stdout.log';
@@ -196,23 +197,35 @@ public function testShouldSplitStderrAndStdout()
             ]
         );
 
-        $this->assertContains('stdout output', @file_get_contents($stdout));
-        $this->assertContains('stderr output', @file_get_contents($stderr));
+        $stdoutContent = file_exists($stdout) ? file_get_contents($stdout) : '';
+        $stderrContent = file_exists($stderr) ? file_get_contents($stderr) : '';
 
-        unlink($stderr);
-        unlink($stdout);
+        $this->assertStringContainsString('stdout output', $stdoutContent);
+        $this->assertStringContainsString('stderr output', $stderrContent);
 
+        if (file_exists($stderr)) {
+            unlink($stderr);
+        }
+        if (file_exists($stdout)) {
+            unlink($stdout);
+        }
     }
 
     /**
      * @covers ::mail
      */
-    public function testNotSendMailOnMissingRecipients()
+    public function testNotSendMailOnMissingRecipients(): void
     {
-        $helper = $this->getMock('Jobby\Helper', ['sendMail']);
+        $helper = $this->createMock(Helper::class);
         $helper->expects($this->never())
             ->method('sendMail')
         ;
+        $helper->method('getHost')->willReturn('localhost');
+        $helper->method('getTempDir')->willReturn(sys_get_temp_dir());
+        $helper->method('getPlatform')->willReturn(Helper::UNIX);
+        $helper->method('escape')->willReturnCallback(function ($input) {
+            return preg_replace('/[^a-z0-9_. -]+/', '', strtolower($input));
+        });
 
         $this->runJob(
             [
@@ -228,12 +241,18 @@ public function testNotSendMailOnMissingRecipients()
     /**
      * @covers ::mail
      */
-    public function testMailShouldTriggerHelper()
+    public function testMailShouldTriggerHelper(): void
     {
-        $helper = $this->getMock('Jobby\Helper', ['sendMail']);
+        $helper = $this->createMock(Helper::class);
         $helper->expects($this->once())
             ->method('sendMail')
         ;
+        $helper->method('getHost')->willReturn('localhost');
+        $helper->method('getTempDir')->willReturn(sys_get_temp_dir());
+        $helper->method('getPlatform')->willReturn(Helper::UNIX);
+        $helper->method('escape')->willReturnCallback(function ($input) {
+            return preg_replace('/[^a-z0-9_. -]+/', '', strtolower($input));
+        });
 
         $this->runJob(
             [
@@ -249,17 +268,26 @@ public function testMailShouldTriggerHelper()
     /**
      * @covers ::checkMaxRuntime
      */
-    public function testCheckMaxRuntime()
+    public function testCheckMaxRuntime(): void
     {
         if ($this->helper->getPlatform() !== Helper::UNIX) {
             $this->markTestSkipped("'maxRuntime' is not supported on Windows");
         }
 
-        $helper = $this->getMock('Jobby\Helper', ['getLockLifetime']);
+        $helper = $this->createMock(Helper::class);
         $helper->expects($this->once())
             ->method('getLockLifetime')
-            ->will($this->returnValue(0))
+            ->willReturn(0)
         ;
+        $helper->method('getHost')->willReturn('localhost');
+        $helper->method('getTempDir')->willReturn(sys_get_temp_dir());
+        $helper->method('getPlatform')->willReturn(Helper::UNIX);
+        $helper->method('escape')->willReturnCallback(function ($input) {
+            return preg_replace('/[^a-z0-9_. -]+/', '', strtolower($input));
+        });
+        $helper->method('acquireLock')->willReturn(null);
+        $helper->method('releaseLock')->willReturn(null);
+        $helper->method('getSystemNullDevice')->willReturn('/dev/null');
 
         $this->runJob(
             [
@@ -275,17 +303,23 @@ public function testCheckMaxRuntime()
     /**
      * @covers ::checkMaxRuntime
      */
-    public function testCheckMaxRuntimeShouldFailIsExceeded()
+    public function testCheckMaxRuntimeShouldFailIsExceeded(): void
     {
         if ($this->helper->getPlatform() !== Helper::UNIX) {
             $this->markTestSkipped("'maxRuntime' is not supported on Windows");
         }
 
-        $helper = $this->getMock('Jobby\Helper', ['getLockLifetime']);
+        $helper = $this->createMock(Helper::class);
         $helper->expects($this->once())
             ->method('getLockLifetime')
-            ->will($this->returnValue(2))
+            ->willReturn(2)
         ;
+        $helper->method('getHost')->willReturn('localhost');
+        $helper->method('getTempDir')->willReturn(sys_get_temp_dir());
+        $helper->method('getPlatform')->willReturn(Helper::UNIX);
+        $helper->method('escape')->willReturnCallback(function ($input) {
+            return preg_replace('/[^a-z0-9_. -]+/', '', strtolower($input));
+        });
 
         $this->runJob(
             [
@@ -295,7 +329,7 @@ public function testCheckMaxRuntimeShouldFailIsExceeded()
             $helper
         );
 
-        $this->assertContains(
+        $this->assertStringContainsString(
             'MaxRuntime of 1 secs exceeded! Current runtime: 2 secs',
             $this->getLogContent()
         );
@@ -308,7 +342,7 @@ public function testCheckMaxRuntimeShouldFailIsExceeded()
      * @param bool $createFile
      * @param bool $jobRuns
      */
-    public function testHaltDir($createFile, $jobRuns)
+    public function testHaltDir($createFile, $jobRuns): void
     {
         $dir = __DIR__ . '/_files';
         $file = $dir . '/' . static::JOB_NAME;
@@ -338,7 +372,7 @@ public function testHaltDir($createFile, $jobRuns)
         $this->assertEquals($jobRuns, is_string($content) && !empty($content));
     }
 
-    public function haltDirProvider()
+    public function haltDirProvider(): array
     {
         return [
             [true, false],
@@ -348,9 +382,9 @@ public function haltDirProvider()
 
     /**
      * @param array  $config
-     * @param Helper $helper
+     * @param Helper|null $helper
      */
-    private function runJob(array $config, Helper $helper = null)
+    private function runJob(array $config, ?Helper $helper = null): void
     {
         $config = $this->getJobConfig($config);
 
@@ -363,7 +397,7 @@ private function runJob(array $config, Helper $helper = null)
      *
      * @return array
      */
-    private function getJobConfig(array $config)
+    private function getJobConfig(array $config): array
     {
         $helper = new Helper();
 
@@ -390,8 +424,8 @@ private function getJobConfig(array $config)
     /**
      * @return string
      */
-    private function getLogContent()
+    private function getLogContent(): string
     {
-        return @file_get_contents($this->logFile);
+        return file_exists($this->logFile) ? file_get_contents($this->logFile) : '';
     }
 }
diff --git a/tests/ExceptionTest.php b/tests/ExceptionTest.php
index c74232d..91a6ff8 100644
--- a/tests/ExceptionTest.php
+++ b/tests/ExceptionTest.php
@@ -3,13 +3,14 @@
 namespace Jobby\Tests;
 
 use Jobby\Exception;
+use PHPUnit\Framework\TestCase;
 
 /**
  * @covers Jobby\Exception
  */
-class ExceptionTest extends \PHPUnit_Framework_TestCase
+class ExceptionTest extends TestCase
 {
-    public function testInheritsBaseException()
+    public function testInheritsBaseException(): void
     {
         $e = new Exception();
         $this->assertTrue($e instanceof \Exception);
diff --git a/tests/HelperTest.php b/tests/HelperTest.php
index b77521b..d95381a 100644
--- a/tests/HelperTest.php
+++ b/tests/HelperTest.php
@@ -2,13 +2,18 @@
 
 namespace Jobby\Tests;
 
+use Jobby\Exception;
 use Jobby\Helper;
+use Jobby\InfoException;
 use Jobby\Jobby;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Mailer\MailerInterface;
+use Symfony\Component\Mime\Address;
 
 /**
  * @coversDefaultClass Jobby\Helper
  */
-class HelperTest extends \PHPUnit_Framework_TestCase
+class HelperTest extends TestCase
 {
     /**
      * @var Helper
@@ -33,7 +38,7 @@ class HelperTest extends \PHPUnit_Framework_TestCase
     /**
      * {@inheritdoc}
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->helper = new Helper();
         $this->tmpDir = $this->helper->getTempDir();
@@ -44,7 +49,7 @@ protected function setUp()
     /**
      * {@inheritdoc}
      */
-    protected function tearDown()
+    protected function tearDown(): void
     {
         unset($_SERVER['APPLICATION_ENV']);
     }
@@ -55,7 +60,7 @@ protected function tearDown()
      *
      * @dataProvider dataProviderTestEscape
      */
-    public function testEscape($input, $expected)
+    public function testEscape($input, $expected): void
     {
         $actual = $this->helper->escape($input);
         $this->assertEquals($expected, $actual);
@@ -64,7 +69,7 @@ public function testEscape($input, $expected)
     /**
      * @return array
      */
-    public function dataProviderTestEscape()
+    public function dataProviderTestEscape(): array
     {
         return [
             ['lower', 'lower'],
@@ -79,7 +84,7 @@ public function dataProviderTestEscape()
     /**
      * @covers ::getPlatform
      */
-    public function testGetPlatform()
+    public function testGetPlatform(): void
     {
         $actual = $this->helper->getPlatform();
         $this->assertContains($actual, [Helper::UNIX, Helper::WINDOWS]);
@@ -88,7 +93,7 @@ public function testGetPlatform()
     /**
      * @covers ::getPlatform
      */
-    public function testPlatformConstants()
+    public function testPlatformConstants(): void
     {
         $this->assertNotEquals(Helper::UNIX, Helper::WINDOWS);
     }
@@ -97,7 +102,7 @@ public function testPlatformConstants()
      * @covers ::acquireLock
      * @covers ::releaseLock
      */
-    public function testAquireAndReleaseLock()
+    public function testAquireAndReleaseLock(): void
     {
         $this->helper->acquireLock($this->lockFile);
         $this->helper->releaseLock($this->lockFile);
@@ -109,7 +114,7 @@ public function testAquireAndReleaseLock()
      * @covers ::acquireLock
      * @covers ::releaseLock
      */
-    public function testLockFileShouldContainCurrentPid()
+    public function testLockFileShouldContainCurrentPid(): void
     {
         $this->helper->acquireLock($this->lockFile);
 
@@ -131,9 +136,11 @@ public function testLockFileShouldContainCurrentPid()
     /**
      * @covers ::getLockLifetime
      */
-    public function testLockLifetimeShouldBeZeroIfFileDoesNotExists()
+    public function testLockLifetimeShouldBeZeroIfFileDoesNotExists(): void
     {
-        unlink($this->lockFile);
+        if (file_exists($this->lockFile)) {
+            unlink($this->lockFile);
+        }
         $this->assertFalse(file_exists($this->lockFile));
         $this->assertEquals(0, $this->helper->getLockLifetime($this->lockFile));
     }
@@ -141,7 +148,7 @@ public function testLockLifetimeShouldBeZeroIfFileDoesNotExists()
     /**
      * @covers ::getLockLifetime
      */
-    public function testLockLifetimeShouldBeZeroIfFileIsEmpty()
+    public function testLockLifetimeShouldBeZeroIfFileIsEmpty(): void
     {
         file_put_contents($this->lockFile, '');
         $this->assertEquals(0, $this->helper->getLockLifetime($this->lockFile));
@@ -150,7 +157,7 @@ public function testLockLifetimeShouldBeZeroIfFileIsEmpty()
     /**
      * @covers ::getLockLifetime
      */
-    public function testLockLifetimeShouldBeZeroIfItContainsAInvalidPid()
+    public function testLockLifetimeShouldBeZeroIfItContainsAInvalidPid(): void
     {
         if ($this->helper->getPlatform() === Helper::WINDOWS) {
             $this->markTestSkipped("Test relies on posix_ functions");
@@ -163,7 +170,7 @@ public function testLockLifetimeShouldBeZeroIfItContainsAInvalidPid()
     /**
      * @covers ::getLockLifetime
      */
-    public function testGetLocklifetime()
+    public function testGetLocklifetime(): void
     {
         if ($this->helper->getPlatform() === Helper::WINDOWS) {
             $this->markTestSkipped("Test relies on posix_ functions");
@@ -182,19 +189,20 @@ public function testGetLocklifetime()
 
     /**
      * @covers ::releaseLock
-     * @expectedException \Jobby\Exception
      */
-    public function testReleaseNonExistin()
+    public function testReleaseNonExistin(): void
     {
+        $this->expectException(Exception::class);
         $this->helper->releaseLock($this->lockFile);
     }
 
     /**
      * @covers ::acquireLock
-     * @expectedException \Jobby\InfoException
      */
-    public function testExceptionIfAquireFails()
+    public function testExceptionIfAquireFails(): void
     {
+        $this->expectException(InfoException::class);
+
         $fh = fopen($this->lockFile, 'r+');
         $this->assertTrue(is_resource($fh));
 
@@ -206,10 +214,10 @@ public function testExceptionIfAquireFails()
 
     /**
      * @covers ::acquireLock
-     * @expectedException \Jobby\Exception
      */
-    public function testAquireLockShouldFailOnSecondTry()
+    public function testAquireLockShouldFailOnSecondTry(): void
     {
+        $this->expectException(Exception::class);
         $this->helper->acquireLock($this->lockFile);
         $this->helper->acquireLock($this->lockFile);
     }
@@ -217,7 +225,7 @@ public function testAquireLockShouldFailOnSecondTry()
     /**
      * @covers ::getTempDir
      */
-    public function testGetTempDir()
+    public function testGetTempDir(): void
     {
         $valid = [sys_get_temp_dir(), getcwd()];
         foreach (['TMP', 'TEMP', 'TMPDIR'] as $key) {
@@ -233,7 +241,7 @@ public function testGetTempDir()
     /**
      * @covers ::getApplicationEnv
      */
-    public function testGetApplicationEnv()
+    public function testGetApplicationEnv(): void
     {
         $_SERVER['APPLICATION_ENV'] = 'foo';
 
@@ -244,7 +252,7 @@ public function testGetApplicationEnv()
     /**
      * @covers ::getApplicationEnv
      */
-    public function testGetApplicationEnvShouldBeNullIfUndefined()
+    public function testGetApplicationEnvShouldBeNullIfUndefined(): void
     {
         $actual = $this->helper->getApplicationEnv();
         $this->assertNull($actual);
@@ -253,7 +261,7 @@ public function testGetApplicationEnvShouldBeNullIfUndefined()
     /**
      * @covers ::getHost
      */
-    public function testGetHostname()
+    public function testGetHostname(): void
     {
         $actual = $this->helper->getHost();
         $this->assertContains($actual, [gethostname(), php_uname('n')]);
@@ -263,9 +271,9 @@ public function testGetHostname()
      * @covers ::sendMail
      * @covers ::getCurrentMailer
      */
-    public function testSendMail()
+    public function testSendMail(): void
     {
-        $mailer = $this->getSwiftMailerMock();
+        $mailer = $this->createMock(MailerInterface::class);
         $mailer->expects($this->once())
             ->method('send')
         ;
@@ -276,37 +284,30 @@ public function testSendMail()
         $config['recipients'] = 'a@a.com,b@b.com';
 
         $helper = new Helper($mailer);
-        $mail = $helper->sendMail('job', $config, 'message');
+        $email = $helper->sendMail('job', $config, 'message');
 
         $host = $helper->getHost();
-        $email = "jobby@$host";
-        $this->assertContains('job', $mail->getSubject());
-        $this->assertContains("[$host]", $mail->getSubject());
-        $this->assertEquals(1, count($mail->getFrom()));
-        $this->assertEquals('jobby', current($mail->getFrom()));
-        $this->assertEquals($email, current(array_keys($mail->getFrom())));
-        $this->assertEquals($email, current(array_keys($mail->getSender())));
-        $this->assertContains($config['output'], $mail->getBody());
-        $this->assertContains('message', $mail->getBody());
-    }
+        $expectedEmail = "jobby@$host";
 
-    /**
-     * @return \Swift_Mailer
-     */
-    private function getSwiftMailerMock()
-    {
-        $nullTransport = new \Swift_NullTransport();
+        $this->assertStringContainsString('job', $email->getSubject());
+        $this->assertStringContainsString("[$host]", $email->getSubject());
+
+        $fromAddresses = $email->getFrom();
+        $this->assertCount(1, $fromAddresses);
+        $this->assertInstanceOf(Address::class, $fromAddresses[0]);
+        $this->assertEquals($expectedEmail, $fromAddresses[0]->getAddress());
+        $this->assertEquals('jobby', $fromAddresses[0]->getName());
 
-        return $this->getMock('Swift_Mailer', [], [$nullTransport]);
+        $this->assertStringContainsString($config['output'], $email->getTextBody());
+        $this->assertStringContainsString('message', $email->getTextBody());
     }
 
     /**
      * @return void
      */
-    public function testItReturnsTheCorrectNullSystemDeviceForUnix()
+    public function testItReturnsTheCorrectNullSystemDeviceForUnix(): void
     {
-        /** @var Helper $helper */
-        $helper = $this->getMock("\\Jobby\\Helper", ["getPlatform"]);
+        $helper = $this->createPartialMock(Helper::class, ["getPlatform"]);
         $helper->expects($this->once())
             ->method("getPlatform")
             ->willReturn(Helper::UNIX);
@@ -317,10 +318,9 @@ public function testItReturnsTheCorrectNullSystemDeviceForUnix()
     /**
      * @return void
      */
-    public function testItReturnsTheCorrectNullSystemDeviceForWindows()
+    public function testItReturnsTheCorrectNullSystemDeviceForWindows(): void
     {
-        /** @var Helper $helper */
-        $helper = $this->getMock("\\Jobby\\Helper", ["getPlatform"]);
+        $helper = $this->createPartialMock(Helper::class, ["getPlatform"]);
         $helper->expects($this->once())
                ->method("getPlatform")
                ->willReturn(Helper::WINDOWS);
diff --git a/tests/JobbyTest.php b/tests/JobbyTest.php
index 9891942..95fc2e9 100644
--- a/tests/JobbyTest.php
+++ b/tests/JobbyTest.php
@@ -2,14 +2,16 @@
 
 namespace Jobby\Tests;
 
+use Jobby\Exception;
 use Jobby\Helper;
 use Jobby\Jobby;
 use Opis\Closure\SerializableClosure;
+use PHPUnit\Framework\TestCase;
 
 /**
  * @coversDefaultClass Jobby\Jobby
  */
-class JobbyTest extends \PHPUnit_Framework_TestCase
+class JobbyTest extends TestCase
 {
     /**
      * @var string
@@ -24,20 +26,20 @@ class JobbyTest extends \PHPUnit_Framework_TestCase
     /**
      * {@inheritdoc}
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->logFile = __DIR__ . '/_files/JobbyTest.log';
         if (file_exists($this->logFile)) {
             unlink($this->logFile);
         }
-        
+
         $this->helper = new Helper();
     }
 
     /**
      * {@inheritdoc}
      */
-    protected function tearDown()
+    protected function tearDown(): void
     {
         if (file_exists($this->logFile)) {
             unlink($this->logFile);
@@ -48,7 +50,7 @@ protected function tearDown()
      * @covers ::add
      * @covers ::run
      */
-    public function testShell()
+    public function testShell(): void
     {
         $jobby = new Jobby();
         $jobby->add(
@@ -70,7 +72,7 @@ public function testShell()
     /**
      * @return void
      */
-    public function testBackgroundProcessIsNotSpawnedIfJobIsNotDueToBeRun()
+    public function testBackgroundProcessIsNotSpawnedIfJobIsNotDueToBeRun(): void
     {
         $hour = date("H", strtotime("+1 hour"));
         $jobby = new Jobby();
@@ -97,7 +99,7 @@ public function testBackgroundProcessIsNotSpawnedIfJobIsNotDueToBeRun()
      * @covers ::add
      * @covers ::run
      */
-    public function testOpisClosure()
+    public function testOpisClosure(): void
     {
         $fn = static function () {
             echo 'Another function!';
@@ -131,7 +133,7 @@ public function testOpisClosure()
      * @covers ::add
      * @covers ::run
      */
-    public function testClosure()
+    public function testClosure(): void
     {
         $jobby = new Jobby();
         $jobby->add(
@@ -158,7 +160,7 @@ public function testClosure()
      * @covers ::add
      * @covers ::run
      */
-    public function testShouldRunAllJobsAdded()
+    public function testShouldRunAllJobsAdded(): void
     {
         $jobby = new Jobby(['output' => $this->logFile]);
         $jobby->add(
@@ -188,15 +190,15 @@ public function testShouldRunAllJobsAdded()
         // Job runs asynchronously, so wait a bit
         sleep($this->getSleepTime());
 
-        $this->assertContains('job-1', $this->getLogContent());
-        $this->assertContains('job-2', $this->getLogContent());
+        $this->assertStringContainsString('job-1', $this->getLogContent());
+        $this->assertStringContainsString('job-2', $this->getLogContent());
     }
 
     /**
      * This is the same test as testClosure but (!) we use the default
      * options to set the output file.
      */
-    public function testDefaultOptionsShouldBeMerged()
+    public function testDefaultOptionsShouldBeMerged(): void
     {
         $jobby = new Jobby(['output' => $this->logFile]);
         $jobby->add(
@@ -221,7 +223,7 @@ public function testDefaultOptionsShouldBeMerged()
     /**
      * @covers ::getDefaultConfig
      */
-    public function testDefaultConfig()
+    public function testDefaultConfig(): void
     {
         $jobby = new Jobby();
         $config = $jobby->getDefaultConfig();
@@ -239,7 +241,7 @@ public function testDefaultConfig()
      * @covers ::setConfig
      * @covers ::getConfig
      */
-    public function testSetConfig()
+    public function testSetConfig(): void
     {
         $jobby = new Jobby();
         $oldCfg = $jobby->getConfig();
@@ -254,11 +256,11 @@ public function testSetConfig()
     /**
      * @covers ::getJobs
      */
-    public function testGetJobs()
+    public function testGetJobs(): void
     {
         $jobby = new Jobby();
         $this->assertCount(0,$jobby->getJobs());
-        
+
         $jobby->add(
             'test job1',
             [
@@ -280,10 +282,11 @@ public function testGetJobs()
 
     /**
      * @covers ::add
-     * @expectedException \Jobby\Exception
      */
-    public function testExceptionOnMissingJobOptionCommand()
+    public function testExceptionOnMissingJobOptionCommand(): void
     {
+        $this->expectException(Exception::class);
+
         $jobby = new Jobby();
 
         $jobby->add(
@@ -296,10 +299,11 @@ public function testExceptionOnMissingJobOptionCommand()
 
     /**
      * @covers ::add
-     * @expectedException \Jobby\Exception
      */
-    public function testExceptionOnMissingJobOptionSchedule()
+    public function testExceptionOnMissingJobOptionSchedule(): void
     {
+        $this->expectException(Exception::class);
+
         $jobby = new Jobby();
 
         $jobby->add(
@@ -316,7 +320,7 @@ public function testExceptionOnMissingJobOptionSchedule()
      * @covers ::runWindows
      * @covers ::runUnix
      */
-    public function testShouldRunJobsAsync()
+    public function testShouldRunJobsAsync(): void
     {
         $jobby = new Jobby();
         $jobby->add(
@@ -336,7 +340,7 @@ public function testShouldRunJobsAsync()
         $this->assertLessThan(0.5, $duration);
     }
 
-    public function testShouldFailIfMaxRuntimeExceeded()
+    public function testShouldFailIfMaxRuntimeExceeded(): void
     {
         if ($this->helper->getPlatform() === Helper::WINDOWS) {
             $this->markTestSkipped("'maxRuntime' is not supported on Windows");
@@ -358,18 +362,18 @@ public function testShouldFailIfMaxRuntimeExceeded()
         $jobby->run();
         sleep(2);
 
-        $this->assertContains('ERROR: MaxRuntime of 1 secs exceeded!', $this->getLogContent());
+        $this->assertStringContainsString('ERROR: MaxRuntime of 1 secs exceeded!', $this->getLogContent());
     }
 
     /**
      * @return string
      */
-    private function getLogContent()
+    private function getLogContent(): string
     {
         return file_get_contents($this->logFile);
     }
 
-    private function getSleepTime()
+    private function getSleepTime(): int
     {
         return $this->helper->getPlatform() === Helper::UNIX ? 1 : 2;
     }
diff --git a/tests/ScheduleCheckerTest.php b/tests/ScheduleCheckerTest.php
index 032386f..bdd40d8 100644
--- a/tests/ScheduleCheckerTest.php
+++ b/tests/ScheduleCheckerTest.php
@@ -4,9 +4,9 @@
 
 use DateTimeImmutable;
 use Jobby\ScheduleChecker;
-use PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase;
 
-class ScheduleCheckerTest extends PHPUnit_Framework_TestCase
+class ScheduleCheckerTest extends TestCase
 {
     /**
      * @var ScheduleChecker
@@ -16,7 +16,7 @@ class ScheduleCheckerTest extends PHPUnit_Framework_TestCase
     /**
      * @return void
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -26,7 +26,7 @@ protected function setUp()
     /**
      * @return void
      */
-    public function test_it_can_detect_a_due_job_from_a_datetime_string()
+    public function test_it_can_detect_a_due_job_from_a_datetime_string(): void
     {
         $this->assertTrue($this->scheduleChecker->isDue(date('Y-m-d H:i:s')));
     }
@@ -34,7 +34,7 @@ public function test_it_can_detect_a_due_job_from_a_datetime_string()
     /**
      * @return void
      */
-    public function test_it_can_detect_if_a_job_is_due_with_a_passed_in_DateTimeImmutable()
+    public function test_it_can_detect_if_a_job_is_due_with_a_passed_in_DateTimeImmutable(): void
     {
         $scheduleChecker = new ScheduleChecker(new DateTimeImmutable("2017-01-02 13:14:59"));
 
@@ -45,7 +45,7 @@ public function test_it_can_detect_if_a_job_is_due_with_a_passed_in_DateTimeImmu
     /**
      * @return void
      */
-    public function test_it_can_detect_a_non_due_job_from_a_datetime_string()
+    public function test_it_can_detect_a_non_due_job_from_a_datetime_string(): void
     {
         $this->assertFalse($this->scheduleChecker->isDue(date('Y-m-d H:i:s', strtotime('tomorrow'))));
     }
@@ -53,7 +53,7 @@ public function test_it_can_detect_a_non_due_job_from_a_datetime_string()
     /**
      * @return void
      */
-    public function test_it_can_detect_a_due_job_from_a_cron_expression()
+    public function test_it_can_detect_a_due_job_from_a_cron_expression(): void
     {
         $this->assertTrue($this->scheduleChecker->isDue("* * * * *"));
     }
@@ -61,7 +61,7 @@ public function test_it_can_detect_a_due_job_from_a_cron_expression()
     /**
      * @return void
      */
-    public function test_it_can_detect_a_due_job_from_a_non_trivial_cron_expression()
+    public function test_it_can_detect_a_due_job_from_a_non_trivial_cron_expression(): void
     {
         $scheduleChecker = new ScheduleChecker(new DateTimeImmutable("2017-04-01 00:00:00"));
 
@@ -71,7 +71,7 @@ public function test_it_can_detect_a_due_job_from_a_non_trivial_cron_expression(
     /**
      * @return void
      */
-    public function test_it_can_detect_a_non_due_job_from_a_cron_expression()
+    public function test_it_can_detect_a_non_due_job_from_a_cron_expression(): void
     {
         $hour = date("H", strtotime('+1 hour'));
         $this->assertFalse($this->scheduleChecker->isDue("* {$hour} * * *"));
@@ -80,7 +80,7 @@ public function test_it_can_detect_a_non_due_job_from_a_cron_expression()
     /**
      * @return void
      */
-    public function test_it_can_use_a_closure_to_detect_a_due_job()
+    public function test_it_can_use_a_closure_to_detect_a_due_job(): void
     {
         $this->assertTrue(
             $this->scheduleChecker->isDue(function() {
@@ -92,7 +92,7 @@ public function test_it_can_use_a_closure_to_detect_a_due_job()
     /**
      * @return void
      */
-    public function test_it_can_use_a_closure_to_detect_a_non_due_job()
+    public function test_it_can_use_a_closure_to_detect_a_non_due_job(): void
     {
         $this->assertFalse(
             $this->scheduleChecker->isDue(function() {
@@ -104,7 +104,7 @@ public function test_it_can_use_a_closure_to_detect_a_non_due_job()
     /**
      * @return void
      */
-    public function test_it_can_detect_if_a_job_is_due_with_a_passed_in_DateTimeImmutable_from_a_cron_expression()
+    public function test_it_can_detect_if_a_job_is_due_with_a_passed_in_DateTimeImmutable_from_a_cron_expression(): void
     {
         $scheduleChecker = new ScheduleChecker(new DateTimeImmutable("2017-01-02 18:14:59"));