diff --git a/README.md b/README.md
index 39fbbc7..fea1820 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,12 @@ Add the dependency to `phpmentors/workflower` into your `composer.json` file as
 composer require phpmentors/workflower "1.4.*"
 ```
 
+when your PHP version >= 8.0, you can install `1.5.*`
+
+```
+composer require phpmentors/workflower "1.5.*"
+```
+
 ## Documentation
 
 * [Quick Start Guide](https://github.com/phpmentors-jp/workflower/blob/master/docs/GUIDE.md)
diff --git a/composer.json b/composer.json
index 28cf1ce..7e54569 100644
--- a/composer.json
+++ b/composer.json
@@ -11,14 +11,15 @@
         }
     ],
     "require": {
-        "php": ">=5.3.9",
+        "php": "^8.0",
         "phpmentors/domain-kata": "~1.4",
         "piece/stagehand-fsm": "~2.6",
-        "symfony/expression-language": "~2.8|~3.0|~4.0"
+        "symfony/expression-language": "~3.4|~4.0|~5.0",
+        "ext-dom": "*"
     },
     "require-dev": {
-        "phake/phake": "~2.0",
-        "phpunit/phpunit": "~4.0"
+        "phake/phake": "^4.0",
+        "phpunit/phpunit": "~8.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/Definition/Bpmn2File.php b/src/Definition/Bpmn2File.php
index 8bb6c71..7afda60 100644
--- a/src/Definition/Bpmn2File.php
+++ b/src/Definition/Bpmn2File.php
@@ -23,7 +23,7 @@ class Bpmn2File implements EntityInterface, IdentifiableInterface
     private $file;
 
     /**
-     * @param string $file
+     * @param  string  $file
      */
     public function __construct($file)
     {
@@ -47,8 +47,7 @@ public function getFile()
     }
 
     /**
-     * @param string $file
-     *
+     * @param  string  $file
      * @return string
      */
     public static function getWorkflowId($file)
diff --git a/src/Definition/Bpmn2Reader.php b/src/Definition/Bpmn2Reader.php
index c36d8d4..a4d7769 100644
--- a/src/Definition/Bpmn2Reader.php
+++ b/src/Definition/Bpmn2Reader.php
@@ -19,8 +19,7 @@
 class Bpmn2Reader implements ServiceInterface
 {
     /**
-     * @param string $file
-     *
+     * @param  string  $file
      * @return Workflow
      *
      * @throws IdAttributeNotFoundException
@@ -37,8 +36,7 @@ public function read($file)
     }
 
     /**
-     * @param string $source
-     *
+     * @param  string  $source
      * @return Workflow
      *
      * @throws IdAttributeNotFoundException
@@ -57,9 +55,8 @@ public function readSource($source)
     }
 
     /**
-     * @param DOMDocument $document
-     * @param int|string  $workflowId
-     *
+     * @param  DOMDocument  $document
+     * @param  int|string  $workflowId
      * @return Workflow
      *
      * @throws IdAttributeNotFoundException
@@ -85,9 +82,9 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
             }
         }
 
-        $flowObjectRoles = array();
+        $flowObjectRoles = [];
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'lane') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -105,18 +102,18 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
             $workflowBuilder->addRole(Workflow::DEFAULT_ROLE_ID);
         }
 
-        $messages = array();
+        $messages = [];
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'message') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
             $messages[$element->getAttribute('id')] = $element->getAttribute('name');
         }
 
-        $operations = array();
+        $operations = [];
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'operation') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -124,7 +121,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'startEvent') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -137,7 +134,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'task') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -150,7 +147,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'serviceTask') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -164,7 +161,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'sendTask') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -179,7 +176,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'exclusiveGateway') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -192,7 +189,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'endEvent') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -200,7 +197,7 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
         }
 
         foreach ($document->getElementsByTagNameNs('http://www.omg.org/spec/BPMN/20100524/MODEL', 'sequenceFlow') as $element) {
-            if (!$element->hasAttribute('id')) {
+            if (! $element->hasAttribute('id')) {
                 throw $this->createIdAttributeNotFoundException($element, $workflowId);
             }
 
@@ -223,9 +220,8 @@ private function readDocument(\DOMDocument $document, $workflowId = null)
     }
 
     /**
-     * @param \DOMElement $element
-     * @param int|string  $workflowId
-     *
+     * @param  \DOMElement  $element
+     * @param  int|string  $workflowId
      * @return IdAttributeNotFoundException
      */
     private function createIdAttributeNotFoundException(\DOMElement $element, $workflowId)
@@ -234,9 +230,8 @@ private function createIdAttributeNotFoundException(\DOMElement $element, $workf
     }
 
     /**
-     * @param array  $flowObjectRoles
-     * @param string $flowObjectId
-     *
+     * @param  array  $flowObjectRoles
+     * @param  string  $flowObjectId
      * @return string
      *
      * @since Method available since Release 1.3.0
diff --git a/src/Definition/Bpmn2WorkflowRepository.php b/src/Definition/Bpmn2WorkflowRepository.php
index 971be77..5796ad1 100644
--- a/src/Definition/Bpmn2WorkflowRepository.php
+++ b/src/Definition/Bpmn2WorkflowRepository.php
@@ -20,7 +20,7 @@ class Bpmn2WorkflowRepository implements WorkflowRepositoryInterface
     /**
      * @var array
      */
-    private $bpmn2Files = array();
+    private $bpmn2Files = [];
 
     /**
      * {@inheritdoc}
@@ -51,7 +51,7 @@ public function remove(EntityInterface $entity)
      */
     public function findById($id)
     {
-        if (!array_key_exists($id, $this->bpmn2Files)) {
+        if (! array_key_exists($id, $this->bpmn2Files)) {
             return null;
         }
 
diff --git a/src/Definition/ErrorToExceptionContext.php b/src/Definition/ErrorToExceptionContext.php
index 3e40a4c..404d9fe 100644
--- a/src/Definition/ErrorToExceptionContext.php
+++ b/src/Definition/ErrorToExceptionContext.php
@@ -25,8 +25,8 @@ class ErrorToExceptionContext
     private $target;
 
     /**
-     * @param int      $errorReportingLevel
-     * @param \Closure $target
+     * @param  int  $errorReportingLevel
+     * @param  \Closure  $target
      */
     public function __construct($errorReportingLevel, \Closure $target)
     {
diff --git a/src/Persistence/WorkflowSerializableInterface.php b/src/Persistence/WorkflowSerializableInterface.php
index a832eeb..f827acd 100644
--- a/src/Persistence/WorkflowSerializableInterface.php
+++ b/src/Persistence/WorkflowSerializableInterface.php
@@ -17,7 +17,7 @@
 interface WorkflowSerializableInterface extends OperationInterface, WorkflowAwareInterface
 {
     /**
-     * @param string $serializedWorkflow
+     * @param  string  $serializedWorkflow
      */
     public function setSerializedWorkflow($serializedWorkflow);
 
diff --git a/src/Persistence/WorkflowSerializerInterface.php b/src/Persistence/WorkflowSerializerInterface.php
index 3e57b88..b697185 100644
--- a/src/Persistence/WorkflowSerializerInterface.php
+++ b/src/Persistence/WorkflowSerializerInterface.php
@@ -18,15 +18,13 @@
 interface WorkflowSerializerInterface extends ServiceInterface
 {
     /**
-     * @param Workflow $workflow
-     *
+     * @param  Workflow  $workflow
      * @return string
      */
     public function serialize(Workflow $workflow);
 
     /**
-     * @param string $workflow
-     *
+     * @param  string  $workflow
      * @return Workflow
      */
     public function deserialize($workflow);
diff --git a/src/Process/EventContext.php b/src/Process/EventContext.php
index 00a55a0..5e95934 100644
--- a/src/Process/EventContext.php
+++ b/src/Process/EventContext.php
@@ -25,8 +25,8 @@ class EventContext implements EventContextInterface
     private $processContext;
 
     /**
-     * @param int|string              $eventId
-     * @param ProcessContextInterface $processContext
+     * @param  int|string  $eventId
+     * @param  ProcessContextInterface  $processContext
      */
     public function __construct($eventId, ProcessContextInterface $processContext)
     {
diff --git a/src/Process/Process.php b/src/Process/Process.php
index 21f909e..2aefd01 100644
--- a/src/Process/Process.php
+++ b/src/Process/Process.php
@@ -47,9 +47,9 @@ class Process implements ServiceInterface
     private $operationRunner;
 
     /**
-     * @param int|string|WorkflowContextInterface $workflowContext
-     * @param WorkflowRepositoryInterface         $workflowRepository
-     * @param OperationRunnerInterface            $operationRunner
+     * @param  int|string|WorkflowContextInterface  $workflowContext
+     * @param  WorkflowRepositoryInterface  $workflowRepository
+     * @param  OperationRunnerInterface  $operationRunner
      */
     public function __construct($workflowContext, WorkflowRepositoryInterface $workflowRepository, OperationRunnerInterface $operationRunner)
     {
@@ -59,7 +59,7 @@ public function __construct($workflowContext, WorkflowRepositoryInterface $workf
     }
 
     /**
-     * @param ExpressionLanguage $expressionLanguage
+     * @param  ExpressionLanguage  $expressionLanguage
      *
      * @since Method available since Release 1.2.0
      */
@@ -69,7 +69,7 @@ public function setExpressionLanguage(ExpressionLanguage $expressionLanguage)
     }
 
     /**
-     * @param EventContextInterface $eventContext
+     * @param  EventContextInterface  $eventContext
      */
     public function start(EventContextInterface $eventContext)
     {
@@ -84,7 +84,7 @@ public function start(EventContextInterface $eventContext)
     }
 
     /**
-     * @param WorkItemContextInterface $workItemContext
+     * @param  WorkItemContextInterface  $workItemContext
      */
     public function allocateWorkItem(WorkItemContextInterface $workItemContext)
     {
@@ -97,7 +97,7 @@ public function allocateWorkItem(WorkItemContextInterface $workItemContext)
     }
 
     /**
-     * @param WorkItemContextInterface $workItemContext
+     * @param  WorkItemContextInterface  $workItemContext
      */
     public function startWorkItem(WorkItemContextInterface $workItemContext)
     {
@@ -110,7 +110,7 @@ public function startWorkItem(WorkItemContextInterface $workItemContext)
     }
 
     /**
-     * @param WorkItemContextInterface $workItemContext
+     * @param  WorkItemContextInterface  $workItemContext
      */
     public function completeWorkItem(WorkItemContextInterface $workItemContext)
     {
@@ -124,7 +124,7 @@ public function completeWorkItem(WorkItemContextInterface $workItemContext)
     }
 
     /**
-     * @param WorkItemContextInterface $workItemContext
+     * @param  WorkItemContextInterface  $workItemContext
      *
      * @throws UnexpectedActivityStateException
      */
@@ -184,8 +184,7 @@ private function createWorkflow()
     }
 
     /**
-     * @param Workflow $workflow
-     *
+     * @param  Workflow  $workflow
      * @return Workflow
      *
      * @since Method available since Release 1.2.0
diff --git a/src/Process/ProcessAwareInterface.php b/src/Process/ProcessAwareInterface.php
index f09ca32..edd028e 100644
--- a/src/Process/ProcessAwareInterface.php
+++ b/src/Process/ProcessAwareInterface.php
@@ -15,7 +15,7 @@
 interface ProcessAwareInterface extends OperationInterface
 {
     /**
-     * @param Process $process
+     * @param  Process  $process
      */
     public function setProcess(Process $process);
 }
diff --git a/src/Process/WorkItemContext.php b/src/Process/WorkItemContext.php
index 92d9cd5..318cb9a 100644
--- a/src/Process/WorkItemContext.php
+++ b/src/Process/WorkItemContext.php
@@ -32,7 +32,7 @@ class WorkItemContext implements WorkItemContextInterface
     private $processContext;
 
     /**
-     * @param ParticipantInterface $participant
+     * @param  ParticipantInterface  $participant
      */
     public function __construct(ParticipantInterface $participant)
     {
@@ -40,7 +40,7 @@ public function __construct(ParticipantInterface $participant)
     }
 
     /**
-     * @param int|string $activityId
+     * @param  int|string  $activityId
      */
     public function setActivityId($activityId)
     {
@@ -48,7 +48,7 @@ public function setActivityId($activityId)
     }
 
     /**
-     * @param ProcessContextInterface $processContext
+     * @param  ProcessContextInterface  $processContext
      */
     public function setProcessContext(ProcessContextInterface $processContext)
     {
@@ -64,7 +64,7 @@ public function getActivityId()
     }
 
     /**
-     * @param ParticipantInterface $participant
+     * @param  ParticipantInterface  $participant
      *
      * @since Method available since Release 1.1.0
      */
diff --git a/src/Process/WorkflowAwareInterface.php b/src/Process/WorkflowAwareInterface.php
index 8b40086..27b8d1d 100644
--- a/src/Process/WorkflowAwareInterface.php
+++ b/src/Process/WorkflowAwareInterface.php
@@ -17,7 +17,7 @@
 interface WorkflowAwareInterface extends OperationInterface
 {
     /**
-     * @param Workflow $workflow
+     * @param  Workflow  $workflow
      */
     public function setWorkflow(Workflow $workflow);
 }
diff --git a/src/Workflow/AccessDeniedException.php b/src/Workflow/AccessDeniedException.php
index fd32b2c..244f396 100644
--- a/src/Workflow/AccessDeniedException.php
+++ b/src/Workflow/AccessDeniedException.php
@@ -15,8 +15,8 @@
 class AccessDeniedException extends \RuntimeException
 {
     /**
-     * @param string     $message
-     * @param \Exception $previous
+     * @param  string  $message
+     * @param  \Exception  $previous
      */
     public function __construct($message = 'Access Denied', \Exception $previous = null)
     {
diff --git a/src/Workflow/Activity/ActivityInterface.php b/src/Workflow/Activity/ActivityInterface.php
index b883aae..c1de80d 100644
--- a/src/Workflow/Activity/ActivityInterface.php
+++ b/src/Workflow/Activity/ActivityInterface.php
@@ -41,8 +41,7 @@ public function isCompletable();
     public function isEnded();
 
     /**
-     * @param int $index
-     *
+     * @param  int  $index
      * @return WorkItemInterface
      *
      * @throws \OutOfBoundsException
diff --git a/src/Workflow/Activity/SendTask.php b/src/Workflow/Activity/SendTask.php
index cf1d858..5bc81b0 100644
--- a/src/Workflow/Activity/SendTask.php
+++ b/src/Workflow/Activity/SendTask.php
@@ -32,10 +32,10 @@ class SendTask extends Task implements MessageInterface, OperationalInterface
     private $operation;
 
     /**
-     * @param int|string $id
-     * @param Role       $role
-     * @param int|string $operation
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  Role  $role
+     * @param  int|string  $operation
+     * @param  string  $name
      */
     public function __construct($id, Role $role, $message, $operation, $name = null)
     {
@@ -48,23 +48,24 @@ public function __construct($id, Role $role, $message, $operation, $name = null)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             get_parent_class($this) => parent::serialize(),
             'message' => $this->message,
             'operation' => $this->operation,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if ($name == get_parent_class($this)) {
                 parent::unserialize($value);
+
                 continue;
             }
 
diff --git a/src/Workflow/Activity/ServiceTask.php b/src/Workflow/Activity/ServiceTask.php
index b317d95..8828518 100644
--- a/src/Workflow/Activity/ServiceTask.php
+++ b/src/Workflow/Activity/ServiceTask.php
@@ -26,10 +26,10 @@ class ServiceTask extends Task implements OperationalInterface
     private $operation;
 
     /**
-     * @param int|string $id
-     * @param Role       $role
-     * @param int|string $operation
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  Role  $role
+     * @param  int|string  $operation
+     * @param  string  $name
      */
     public function __construct($id, Role $role, $operation, $name = null)
     {
@@ -41,22 +41,23 @@ public function __construct($id, Role $role, $operation, $name = null)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             get_parent_class($this) => parent::serialize(),
             'operation' => $this->operation,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if ($name == get_parent_class($this)) {
                 parent::unserialize($value);
+
                 continue;
             }
 
diff --git a/src/Workflow/Activity/Task.php b/src/Workflow/Activity/Task.php
index 137d3d8..34ce81b 100644
--- a/src/Workflow/Activity/Task.php
+++ b/src/Workflow/Activity/Task.php
@@ -16,7 +16,7 @@
 use PHPMentors\Workflower\Workflow\Participant\ParticipantInterface;
 use PHPMentors\Workflower\Workflow\Participant\Role;
 
-class Task implements ActivityInterface, \Serializable
+class Task implements ActivityInterface
 {
     /**
      * @var int|string
@@ -36,7 +36,7 @@ class Task implements ActivityInterface, \Serializable
     /**
      * @var WorkItemInterface[]
      */
-    private $workItems = array();
+    private $workItems = [];
 
     /**
      * @var int|string
@@ -44,9 +44,9 @@ class Task implements ActivityInterface, \Serializable
     private $defaultSequenceFlowId;
 
     /**
-     * @param int|string $id
-     * @param Role       $role
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  Role  $role
+     * @param  string  $name
      */
     public function __construct($id, Role $role, $name = null)
     {
@@ -58,21 +58,21 @@ public function __construct($id, Role $role, $name = null)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'role' => $this->role,
             'name' => $this->name,
             'workItems' => $this->workItems,
             'defaultSequenceFlowId' => $this->defaultSequenceFlowId,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -112,7 +112,7 @@ public function getName()
      */
     public function equals(EntityInterface $target)
     {
-        if (!($target instanceof self)) {
+        if (! ($target instanceof self)) {
             return false;
         }
 
@@ -236,7 +236,7 @@ public function getEndResult()
      */
     public function createWorkItem()
     {
-        if (!(count($this->workItems) == 0 || $this->isEnded())) {
+        if (! (count($this->workItems) == 0 || $this->isEnded())) {
             throw new UnexpectedActivityStateException(sprintf('The current work item of the activity "%s" is not ended.', $this->getId()));
         }
 
@@ -248,7 +248,7 @@ public function createWorkItem()
      */
     public function allocate(ParticipantInterface $participant)
     {
-        if (!$this->isAllocatable()) {
+        if (! $this->isAllocatable()) {
             throw new UnexpectedActivityStateException(sprintf('The current work item of the activity "%s" is not allocatable.', $this->getId()));
         }
 
@@ -260,7 +260,7 @@ public function allocate(ParticipantInterface $participant)
      */
     public function start()
     {
-        if (!$this->isStartable()) {
+        if (! $this->isStartable()) {
             throw new UnexpectedActivityStateException(sprintf('The current work item of the activity "%s" is not startable.', $this->getId()));
         }
 
@@ -272,7 +272,7 @@ public function start()
      */
     public function complete(ParticipantInterface $participant)
     {
-        if (!$this->isCompletable()) {
+        if (! $this->isCompletable()) {
             throw new UnexpectedActivityStateException(sprintf('The current work item of the activity "%s" is not completable.', $this->getId()));
         }
 
@@ -316,7 +316,7 @@ public function isEnded()
      */
     public function getWorkItem($index)
     {
-        if (!array_key_exists($index, $this->workItems)) {
+        if (! array_key_exists($index, $this->workItems)) {
             throw new \OutOfBoundsException(sprintf('The index "%d" is not in the range [0, %d].', $index, count($this->workItems) - 1));
         }
 
diff --git a/src/Workflow/Activity/WorkItem.php b/src/Workflow/Activity/WorkItem.php
index cabc586..90a5b16 100644
--- a/src/Workflow/Activity/WorkItem.php
+++ b/src/Workflow/Activity/WorkItem.php
@@ -5,7 +5,7 @@
 use PHPMentors\Workflower\Workflow\Participant\LoggedParticipant;
 use PHPMentors\Workflower\Workflow\Participant\ParticipantInterface;
 
-class WorkItem implements WorkItemInterface, \Serializable
+class WorkItem implements WorkItemInterface
 {
     /**
      * @var string
@@ -55,9 +55,9 @@ public function __construct()
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'currentState' => $this->currentState,
             'participant' => $this->participant === null ? null : ($this->participant instanceof LoggedParticipant ? $this->participant : new LoggedParticipant($this->participant)),
             'creationDate' => $this->creationDate,
@@ -66,13 +66,13 @@ public function serialize()
             'endDate' => $this->endDate,
             'endParticipant' => $this->endParticipant === null ? null : ($this->endParticipant instanceof LoggedParticipant ? $this->endParticipant : new LoggedParticipant($this->endParticipant)),
             'endResult' => $this->endResult,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
diff --git a/src/Workflow/Activity/WorkItemInterface.php b/src/Workflow/Activity/WorkItemInterface.php
index 34a75b7..5b6237a 100644
--- a/src/Workflow/Activity/WorkItemInterface.php
+++ b/src/Workflow/Activity/WorkItemInterface.php
@@ -18,9 +18,13 @@
 interface WorkItemInterface extends EntityInterface
 {
     const STATE_CREATED = 'created';
+
     const STATE_ALLOCATED = 'allocated';
+
     const STATE_STARTED = 'started';
+
     const STATE_ENDED = 'ended';
+
     const END_RESULT_COMPLETION = 'completion';
 
     /**
@@ -64,14 +68,14 @@ public function getEndParticipant();
     public function getEndResult();
 
     /**
-     * @param ParticipantInterface $participant
+     * @param  ParticipantInterface  $participant
      */
     public function allocate(ParticipantInterface $participant);
 
     public function start();
 
     /**
-     * @param ParticipantInterface $participant
+     * @param  ParticipantInterface  $participant
      */
     public function complete(ParticipantInterface $participant);
 }
diff --git a/src/Workflow/ActivityLog.php b/src/Workflow/ActivityLog.php
index 16f5696..6022395 100644
--- a/src/Workflow/ActivityLog.php
+++ b/src/Workflow/ActivityLog.php
@@ -29,7 +29,7 @@ class ActivityLog implements EntityInterface
     private $workItem;
 
     /**
-     * @param ActivityInterface $activity
+     * @param  ActivityInterface  $activity
      */
     public function __construct(ActivityInterface $activity)
     {
@@ -45,7 +45,7 @@ public function getActivity()
     }
 
     /**
-     * @param WorkItemInterface $workItem
+     * @param  WorkItemInterface  $workItem
      */
     public function setWorkItem(WorkItemInterface $workItem)
     {
diff --git a/src/Workflow/ActivityLogCollection.php b/src/Workflow/ActivityLogCollection.php
index 4520bba..6f7495a 100644
--- a/src/Workflow/ActivityLogCollection.php
+++ b/src/Workflow/ActivityLogCollection.php
@@ -15,18 +15,19 @@
 use PHPMentors\DomainKata\Entity\EntityCollectionInterface;
 use PHPMentors\DomainKata\Entity\EntityInterface;
 use PHPMentors\Workflower\Workflow\Activity\ActivityInterface;
+use Traversable;
 
 class ActivityLogCollection implements EntityCollectionInterface
 {
     /**
      * @var ActivityLog[]
      */
-    private $activityLogs = array();
+    private $activityLogs = [];
 
     /**
      * @var array
      */
-    private $lastWorkItemIndexByActivity = array();
+    private $lastWorkItemIndexByActivity = [];
 
     /**
      * {@inheritdoc}
@@ -38,7 +39,7 @@ public function add(EntityInterface $entity)
         $this->activityLogs[] = $entity;
 
         if (array_key_exists($entity->getActivity()->getId(), $this->lastWorkItemIndexByActivity)) {
-            ++$this->lastWorkItemIndexByActivity[$entity->getActivity()->getId()];
+            $this->lastWorkItemIndexByActivity[$entity->getActivity()->getId()]++;
         } else {
             $this->lastWorkItemIndexByActivity[$entity->getActivity()->getId()] = 0;
         }
@@ -53,7 +54,7 @@ public function add(EntityInterface $entity)
      */
     public function get($key)
     {
-        if (!array_key_exists($key, $this->activityLogs)) {
+        if (! array_key_exists($key, $this->activityLogs)) {
             return null;
         }
 
@@ -71,7 +72,7 @@ public function remove(EntityInterface $entity)
     /**
      * {@inheritdoc}
      */
-    public function count()
+    public function count(): int
     {
         return count($this->activityLogs);
     }
@@ -79,7 +80,7 @@ public function count()
     /**
      * {@inheritdoc}
      */
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new \ArrayIterator($this->activityLogs);
     }
diff --git a/src/Workflow/Connection/SequenceFlow.php b/src/Workflow/Connection/SequenceFlow.php
index 02dec21..074547a 100644
--- a/src/Workflow/Connection/SequenceFlow.php
+++ b/src/Workflow/Connection/SequenceFlow.php
@@ -18,7 +18,7 @@
 use PHPMentors\Workflower\Workflow\Element\TransitionalInterface;
 use Symfony\Component\ExpressionLanguage\Expression;
 
-class SequenceFlow implements ConnectingObjectInterface, \Serializable
+class SequenceFlow implements ConnectingObjectInterface
 {
     /**
      * @var int|string
@@ -47,10 +47,10 @@ class SequenceFlow implements ConnectingObjectInterface, \Serializable
 
     /**
      * @param int|string
-     * @param TransitionalInterface $source
-     * @param FlowObjectInterface   $destination
-     * @param string                $name
-     * @param Expression            $condition
+     * @param  TransitionalInterface  $source
+     * @param  FlowObjectInterface  $destination
+     * @param  string  $name
+     * @param  Expression  $condition
      */
     public function __construct($id, TransitionalInterface $source, FlowObjectInterface $destination, $name = null, Expression $condition = null)
     {
@@ -64,21 +64,21 @@ public function __construct($id, TransitionalInterface $source, FlowObjectInterf
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'name' => $this->name,
             'source' => $this->source,
             'destination' => $this->destination,
             'condition' => $this->condition,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -134,7 +134,7 @@ public function getCondition()
      */
     public function equals(EntityInterface $target)
     {
-        if (!($target instanceof self)) {
+        if (! ($target instanceof self)) {
             return false;
         }
 
diff --git a/src/Workflow/Element/ConditionalInterface.php b/src/Workflow/Element/ConditionalInterface.php
index 31e725e..581f595 100644
--- a/src/Workflow/Element/ConditionalInterface.php
+++ b/src/Workflow/Element/ConditionalInterface.php
@@ -15,7 +15,7 @@
 interface ConditionalInterface extends OperationInterface
 {
     /**
-     * @param int|string $sequenceFlowId
+     * @param  int|string  $sequenceFlowId
      */
     public function setDefaultSequenceFlowId($sequenceFlowId);
 
diff --git a/src/Workflow/Element/ConnectingObjectCollection.php b/src/Workflow/Element/ConnectingObjectCollection.php
index 7d8bf11..7de757d 100644
--- a/src/Workflow/Element/ConnectingObjectCollection.php
+++ b/src/Workflow/Element/ConnectingObjectCollection.php
@@ -14,28 +14,29 @@
 
 use PHPMentors\DomainKata\Entity\EntityCollectionInterface;
 use PHPMentors\DomainKata\Entity\EntityInterface;
+use Traversable;
 
-class ConnectingObjectCollection implements EntityCollectionInterface, \Serializable
+class ConnectingObjectCollection implements EntityCollectionInterface
 {
     /**
      * @var array
      */
-    private $connectingObjects = array();
+    private $connectingObjects = [];
 
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'connectingObjects' => $this->connectingObjects,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -61,7 +62,7 @@ public function add(EntityInterface $entity)
      */
     public function get($key)
     {
-        if (!array_key_exists($key, $this->connectingObjects)) {
+        if (! array_key_exists($key, $this->connectingObjects)) {
             return null;
         }
 
@@ -79,7 +80,7 @@ public function remove(EntityInterface $entity)
     /**
      * {@inheritdoc}
      */
-    public function count()
+    public function count(): int
     {
         return count($this->connectingObjects);
     }
@@ -87,14 +88,13 @@ public function count()
     /**
      * {@inheritdoc}
      */
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new \ArrayIterator($this->connectingObjects);
     }
 
     /**
-     * @param TransitionalInterface $flowObject
-     *
+     * @param  TransitionalInterface  $flowObject
      * @return ConnectingObjectCollection
      */
     public function filterBySource(TransitionalInterface $flowObject)
diff --git a/src/Workflow/Element/FlowObjectCollection.php b/src/Workflow/Element/FlowObjectCollection.php
index b022867..755a6ee 100644
--- a/src/Workflow/Element/FlowObjectCollection.php
+++ b/src/Workflow/Element/FlowObjectCollection.php
@@ -14,28 +14,29 @@
 
 use PHPMentors\DomainKata\Entity\EntityCollectionInterface;
 use PHPMentors\DomainKata\Entity\EntityInterface;
+use Traversable;
 
-class FlowObjectCollection implements EntityCollectionInterface, \Serializable
+class FlowObjectCollection implements EntityCollectionInterface
 {
     /**
      * @var array
      */
-    private $flowObjects = array();
+    private $flowObjects = [];
 
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'flowObjects' => $this->flowObjects,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -61,7 +62,7 @@ public function add(EntityInterface $entity)
      */
     public function get($key)
     {
-        if (!array_key_exists($key, $this->flowObjects)) {
+        if (! array_key_exists($key, $this->flowObjects)) {
             return null;
         }
 
@@ -79,7 +80,7 @@ public function remove(EntityInterface $entity)
     /**
      * {@inheritdoc}
      */
-    public function count()
+    public function count(): int
     {
         return count($this->flowObjects);
     }
@@ -87,7 +88,7 @@ public function count()
     /**
      * {@inheritdoc}
      */
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new \ArrayIterator($this->flowObjects);
     }
diff --git a/src/Workflow/Event/Event.php b/src/Workflow/Event/Event.php
index 63b7fef..5729be4 100644
--- a/src/Workflow/Event/Event.php
+++ b/src/Workflow/Event/Event.php
@@ -15,7 +15,7 @@
 use PHPMentors\DomainKata\Entity\EntityInterface;
 use PHPMentors\Workflower\Workflow\Participant\Role;
 
-abstract class Event implements \Serializable
+abstract class Event
 {
     /**
      * @var int|string
@@ -33,9 +33,9 @@ abstract class Event implements \Serializable
     private $role;
 
     /**
-     * @param int|string $id
-     * @param Role       $role
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  Role  $role
+     * @param  string  $name
      */
     public function __construct($id, Role $role, $name = null)
     {
@@ -44,22 +44,16 @@ public function __construct($id, Role $role, $name = null)
         $this->name = $name;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'name' => $this->name,
             'role' => $this->role,
-        ));
+        ]);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -69,8 +63,6 @@ public function unserialize($serialized)
     }
 
     /**
-     * {@inheritdoc}
-     *
      * @return string
      */
     public function getId()
@@ -86,20 +78,14 @@ public function getName()
         return $this->name;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function getRole()
     {
         return $this->role;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function equals(EntityInterface $target)
     {
-        if (!($target instanceof self)) {
+        if (! ($target instanceof self)) {
             return false;
         }
 
diff --git a/src/Workflow/Gateway/ExclusiveGateway.php b/src/Workflow/Gateway/ExclusiveGateway.php
index a7be350..d983169 100644
--- a/src/Workflow/Gateway/ExclusiveGateway.php
+++ b/src/Workflow/Gateway/ExclusiveGateway.php
@@ -15,7 +15,7 @@
 use PHPMentors\DomainKata\Entity\EntityInterface;
 use PHPMentors\Workflower\Workflow\Participant\Role;
 
-class ExclusiveGateway implements GatewayInterface, \Serializable
+class ExclusiveGateway implements GatewayInterface
 {
     /**
      * @var int|string
@@ -38,9 +38,9 @@ class ExclusiveGateway implements GatewayInterface, \Serializable
     private $defaultSequenceFlowId;
 
     /**
-     * @param int|string $id
-     * @param Role       $role
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  Role  $role
+     * @param  string  $name
      */
     public function __construct($id, Role $role, $name = null)
     {
@@ -52,20 +52,20 @@ public function __construct($id, Role $role, $name = null)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'name' => $this->name,
             'role' => $this->role,
             'defaultSequenceFlowId' => $this->defaultSequenceFlowId,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -105,7 +105,7 @@ public function getName()
      */
     public function equals(EntityInterface $target)
     {
-        if (!($target instanceof self)) {
+        if (! ($target instanceof self)) {
             return false;
         }
 
diff --git a/src/Workflow/Operation/OperationRunnerInterface.php b/src/Workflow/Operation/OperationRunnerInterface.php
index 261b2cd..7c46f20 100644
--- a/src/Workflow/Operation/OperationRunnerInterface.php
+++ b/src/Workflow/Operation/OperationRunnerInterface.php
@@ -23,16 +23,15 @@
 interface OperationRunnerInterface extends ServiceInterface
 {
     /**
-     * @param ActivityInterface $activity
-     * @param Workflow          $workflow
-     *
+     * @param  ActivityInterface  $activity
+     * @param  Workflow  $workflow
      * @return ParticipantInterface
      */
     public function provideParticipant(OperationalInterface $operational, Workflow $workflow);
 
     /**
-     * @param OperationalInterface $operational
-     * @param Workflow             $workflow
+     * @param  OperationalInterface  $operational
+     * @param  Workflow  $workflow
      */
     public function run(OperationalInterface $operational, Workflow $workflow);
 }
diff --git a/src/Workflow/Participant/LoggedParticipant.php b/src/Workflow/Participant/LoggedParticipant.php
index 00bd6da..edfb425 100644
--- a/src/Workflow/Participant/LoggedParticipant.php
+++ b/src/Workflow/Participant/LoggedParticipant.php
@@ -14,7 +14,7 @@
 
 use PHPMentors\Workflower\Workflow\Resource\ResourceInterface;
 
-class LoggedParticipant implements ParticipantInterface, \Serializable
+class LoggedParticipant implements ParticipantInterface
 {
     /**
      * @var int|string
@@ -27,7 +27,7 @@ class LoggedParticipant implements ParticipantInterface, \Serializable
     private $name;
 
     /**
-     * @param ParticipantInterface $participant
+     * @param  ParticipantInterface  $participant
      */
     public function __construct(ParticipantInterface $participant)
     {
@@ -38,18 +38,18 @@ public function __construct(ParticipantInterface $participant)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'name' => $this->name,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -99,7 +99,7 @@ public function getName()
     }
 
     /**
-     * @param string $method
+     * @param  string  $method
      *
      * @throws OperationNotSupportedException
      */
diff --git a/src/Workflow/Participant/ParticipantInterface.php b/src/Workflow/Participant/ParticipantInterface.php
index 90f96ae..6f9813c 100644
--- a/src/Workflow/Participant/ParticipantInterface.php
+++ b/src/Workflow/Participant/ParticipantInterface.php
@@ -18,14 +18,13 @@
 interface ParticipantInterface extends OperationInterface, IdentifiableInterface
 {
     /**
-     * @param string $role
-     *
+     * @param  string  $role
      * @return bool
      */
     public function hasRole($role);
 
     /**
-     * @param ResourceInterface $resource
+     * @param  ResourceInterface  $resource
      */
     public function setResource(ResourceInterface $resource);
 
diff --git a/src/Workflow/Participant/Role.php b/src/Workflow/Participant/Role.php
index 62714d8..f37cd5c 100644
--- a/src/Workflow/Participant/Role.php
+++ b/src/Workflow/Participant/Role.php
@@ -15,7 +15,7 @@
 use PHPMentors\DomainKata\Entity\EntityInterface;
 use PHPMentors\DomainKata\Entity\Operation\IdentifiableInterface;
 
-class Role implements EntityInterface, IdentifiableInterface, \Serializable
+class Role implements EntityInterface, IdentifiableInterface
 {
     /**
      * @var int|string
@@ -28,8 +28,8 @@ class Role implements EntityInterface, IdentifiableInterface, \Serializable
     private $name;
 
     /**
-     * @param int|string $id
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  string  $name
      */
     public function __construct($id, $name = null)
     {
@@ -40,18 +40,18 @@ public function __construct($id, $name = null)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'id' => $this->id,
             'name' => $this->name,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
diff --git a/src/Workflow/Participant/RoleCollection.php b/src/Workflow/Participant/RoleCollection.php
index 0b31c80..039ec29 100644
--- a/src/Workflow/Participant/RoleCollection.php
+++ b/src/Workflow/Participant/RoleCollection.php
@@ -14,28 +14,29 @@
 
 use PHPMentors\DomainKata\Entity\EntityCollectionInterface;
 use PHPMentors\DomainKata\Entity\EntityInterface;
+use Traversable;
 
-class RoleCollection implements EntityCollectionInterface, \Serializable
+class RoleCollection implements EntityCollectionInterface
 {
     /**
      * @var array
      */
-    private $roles = array();
+    private $roles = [];
 
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'roles' => $this->roles,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -79,7 +80,7 @@ public function remove(EntityInterface $entity)
     /**
      * {@inheritdoc}
      */
-    public function count()
+    public function count(): int
     {
         return count($this->roles);
     }
@@ -87,7 +88,7 @@ public function count()
     /**
      * {@inheritdoc}
      */
-    public function getIterator()
+    public function getIterator(): Traversable
     {
         return new \ArrayIterator($this->roles);
     }
diff --git a/src/Workflow/Workflow.php b/src/Workflow/Workflow.php
index 6b43e75..b8c2a56 100644
--- a/src/Workflow/Workflow.php
+++ b/src/Workflow/Workflow.php
@@ -40,7 +40,7 @@
 use Stagehand\FSM\StateMachine\StateMachineInterface;
 use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
 
-class Workflow implements EntityInterface, IdentifiableInterface, \Serializable
+class Workflow implements EntityInterface, IdentifiableInterface
 {
     const DEFAULT_ROLE_ID = '__ROLE__';
 
@@ -104,8 +104,8 @@ class Workflow implements EntityInterface, IdentifiableInterface, \Serializable
     private $operationRunner;
 
     /**
-     * @param int|string $id
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  string  $name
      */
     public function __construct($id, $name)
     {
@@ -119,9 +119,9 @@ public function __construct($id, $name)
     /**
      * {@inheritdoc}
      */
-    public function serialize()
+    public function __serialize()
     {
-        return serialize(array(
+        return serialize([
             'name' => $this->name,
             'connectingObjectCollection' => $this->connectingObjectCollection,
             'flowObjectCollection' => $this->flowObjectCollection,
@@ -129,13 +129,13 @@ public function serialize()
             'startDate' => $this->startDate,
             'endDate' => $this->endDate,
             'stateMachine' => $this->stateMachine,
-        ));
+        ]);
     }
 
     /**
      * {@inheritdoc}
      */
-    public function unserialize($serialized)
+    public function __unserialize($serialized)
     {
         foreach (unserialize($serialized) as $name => $value) {
             if (property_exists($this, $name)) {
@@ -163,7 +163,7 @@ public function getName()
     }
 
     /**
-     * @param ConnectingObjectInterface $connectingObject
+     * @param  ConnectingObjectInterface  $connectingObject
      */
     public function addConnectingObject(ConnectingObjectInterface $connectingObject)
     {
@@ -179,7 +179,7 @@ public function addConnectingObject(ConnectingObjectInterface $connectingObject)
     }
 
     /**
-     * @param FlowObjectInterface $flowObject
+     * @param  FlowObjectInterface  $flowObject
      */
     public function addFlowObject(FlowObjectInterface $flowObject)
     {
@@ -206,8 +206,7 @@ public function addFlowObject(FlowObjectInterface $flowObject)
     }
 
     /**
-     * @param int|string $id
-     *
+     * @param  int|string  $id
      * @return ConnectingObjectInterface|null
      */
     public function getConnectingObject($id)
@@ -216,8 +215,7 @@ public function getConnectingObject($id)
     }
 
     /**
-     * @param TransitionalInterface $flowObject
-     *
+     * @param  TransitionalInterface  $flowObject
      * @return ConnectingObjectCollection
      */
     public function getConnectingObjectCollectionBySource(TransitionalInterface $flowObject)
@@ -226,8 +224,7 @@ public function getConnectingObjectCollectionBySource(TransitionalInterface $flo
     }
 
     /**
-     * @param int|string $id
-     *
+     * @param  int|string  $id
      * @return FlowObjectInterface|null
      */
     public function getFlowObject($id)
@@ -236,7 +233,7 @@ public function getFlowObject($id)
     }
 
     /**
-     * @param Role $role
+     * @param  Role  $role
      */
     public function addRole(Role $role)
     {
@@ -244,8 +241,7 @@ public function addRole(Role $role)
     }
 
     /**
-     * @param int|string $id
-     *
+     * @param  int|string  $id
      * @return bool
      */
     public function hasRole($id)
@@ -254,8 +250,7 @@ public function hasRole($id)
     }
 
     /**
-     * @param int|string $id
-     *
+     * @param  int|string  $id
      * @return Role
      */
     public function getRole($id)
@@ -329,8 +324,8 @@ public function start(StartEvent $event)
     }
 
     /**
-     * @param ActivityInterface    $activity
-     * @param ParticipantInterface $participant
+     * @param  ActivityInterface  $activity
+     * @param  ParticipantInterface  $participant
      */
     public function allocateWorkItem(ActivityInterface $activity, ParticipantInterface $participant)
     {
@@ -341,8 +336,8 @@ public function allocateWorkItem(ActivityInterface $activity, ParticipantInterfa
     }
 
     /**
-     * @param ActivityInterface    $activity
-     * @param ParticipantInterface $participant
+     * @param  ActivityInterface  $activity
+     * @param  ParticipantInterface  $participant
      */
     public function startWorkItem(ActivityInterface $activity, ParticipantInterface $participant)
     {
@@ -353,8 +348,8 @@ public function startWorkItem(ActivityInterface $activity, ParticipantInterface
     }
 
     /**
-     * @param ActivityInterface    $activity
-     * @param ParticipantInterface $participant
+     * @param  ActivityInterface  $activity
+     * @param  ParticipantInterface  $participant
      */
     public function completeWorkItem(ActivityInterface $activity, ParticipantInterface $participant)
     {
@@ -367,7 +362,7 @@ public function completeWorkItem(ActivityInterface $activity, ParticipantInterfa
     }
 
     /**
-     * @param array $processData
+     * @param  array  $processData
      */
     public function setProcessData(array $processData)
     {
@@ -385,7 +380,7 @@ public function getProcessData()
     }
 
     /**
-     * @param ExpressionLanguage $expressionLanguage
+     * @param  ExpressionLanguage  $expressionLanguage
      *
      * @since Method available since Release 1.1.0
      */
@@ -395,7 +390,7 @@ public function setExpressionLanguage(ExpressionLanguage $expressionLanguage)
     }
 
     /**
-     * @param OperationRunnerInterface $operationRunner
+     * @param  OperationRunnerInterface  $operationRunner
      *
      * @since Method available since Release 1.2.0
      */
@@ -405,7 +400,7 @@ public function setOperationRunner(OperationRunnerInterface $operationRunner)
     }
 
     /**
-     * @param EndEvent $event
+     * @param  EndEvent  $event
      */
     private function end(EndEvent $event)
     {
@@ -446,8 +441,7 @@ public function getActivityLog()
     }
 
     /**
-     * @param string $stateMachineName
-     *
+     * @param  string  $stateMachineName
      * @return StateMachineInterface
      */
     private function createStateMachine($stateMachineName)
@@ -468,7 +462,7 @@ private function createStateMachine($stateMachineName)
     }
 
     /**
-     * @param TransitionalInterface $currentFlowObject
+     * @param  TransitionalInterface  $currentFlowObject
      *
      * @throws SequenceFlowNotSelectedException
      */
@@ -476,7 +470,7 @@ private function selectSequenceFlow(TransitionalInterface $currentFlowObject)
     {
         foreach ($this->connectingObjectCollection->filterBySource($currentFlowObject) as $connectingObject) { /* @var $connectingObject ConnectingObjectInterface */
             if ($connectingObject instanceof SequenceFlow) {
-                if (!($currentFlowObject instanceof ConditionalInterface) || $connectingObject->getId() !== $currentFlowObject->getDefaultSequenceFlowId()) {
+                if (! ($currentFlowObject instanceof ConditionalInterface) || $connectingObject->getId() !== $currentFlowObject->getDefaultSequenceFlowId()) {
                     $condition = $connectingObject->getCondition();
                     if ($condition === null) {
                         $selectedSequenceFlow = $connectingObject;
@@ -492,8 +486,8 @@ private function selectSequenceFlow(TransitionalInterface $currentFlowObject)
             }
         }
 
-        if (!isset($selectedSequenceFlow)) {
-            if (!($currentFlowObject instanceof ConditionalInterface) || $currentFlowObject->getDefaultSequenceFlowId() === null) {
+        if (! isset($selectedSequenceFlow)) {
+            if (! ($currentFlowObject instanceof ConditionalInterface) || $currentFlowObject->getDefaultSequenceFlowId() === null) {
                 throw new SequenceFlowNotSelectedException(sprintf('No sequence flow can be selected on "%s".', $currentFlowObject->getId()));
             }
 
@@ -508,26 +502,26 @@ private function selectSequenceFlow(TransitionalInterface $currentFlowObject)
     }
 
     /**
-     * @param ActivityInterface    $activity
-     * @param ParticipantInterface $participant
+     * @param  ActivityInterface  $activity
+     * @param  ParticipantInterface  $participant
      *
      * @throws AccessDeniedException
      */
     private function assertParticipantHasRole(ActivityInterface $activity, ParticipantInterface $participant)
     {
-        if (!$participant->hasRole($activity->getRole()->getId())) {
+        if (! $participant->hasRole($activity->getRole()->getId())) {
             throw new AccessDeniedException(sprintf('The participant "%s" does not have the role "%s" that is required to operate the activity "%s".', $participant->getId(), $activity->getRole()->getId(), $activity->getId()));
         }
     }
 
     /**
-     * @param ActivityInterface $activity
+     * @param  ActivityInterface  $activity
      *
      * @throws UnexpectedActivityException
      */
     private function assertCurrentFlowObjectIsExpectedActivity(ActivityInterface $activity)
     {
-        if (!$activity->equals($this->getCurrentFlowObject())) {
+        if (! $activity->equals($this->getCurrentFlowObject())) {
             throw new UnexpectedActivityException(sprintf('The current flow object is not equal to the expected activity "%s".', $activity->getId()));
         }
     }
diff --git a/src/Workflow/WorkflowBuilder.php b/src/Workflow/WorkflowBuilder.php
index 99f371a..4fa18bc 100644
--- a/src/Workflow/WorkflowBuilder.php
+++ b/src/Workflow/WorkflowBuilder.php
@@ -27,46 +27,46 @@ class WorkflowBuilder
     /**
      * @var array
      */
-    private $endEvents = array();
+    private $endEvents = [];
 
     /**
      * @var array
      */
-    private $exclusiveGateways = array();
+    private $exclusiveGateways = [];
 
     /**
      * @var array
      */
-    private $roles = array();
+    private $roles = [];
 
     /**
      * @var array
      */
-    private $sequenceFlows = array();
+    private $sequenceFlows = [];
 
     /**
      * @var array
      */
-    private $startEvents = array();
+    private $startEvents = [];
 
     /**
      * @var array
      */
-    private $tasks = array();
+    private $tasks = [];
 
     /**
      * @var array
      *
      * @since Property available since Release 1.2.0
      */
-    private $serviceTasks = array();
+    private $serviceTasks = [];
 
     /**
      * @var array
      *
      * @since Property available since Release 1.3.0
      */
-    private $sendTasks = array();
+    private $sendTasks = [];
 
     /**
      * @var string
@@ -81,11 +81,11 @@ class WorkflowBuilder
     /**
      * @var array
      */
-    private $defaultableFlowObjects = array();
+    private $defaultableFlowObjects = [];
 
     /**
-     * @param int|string $workflowId
-     * @param int|string $workflowName
+     * @param  int|string  $workflowId
+     * @param  int|string  $workflowName
      */
     public function __construct($workflowId = null, $workflowName = null)
     {
@@ -94,7 +94,7 @@ public function __construct($workflowId = null, $workflowName = null)
     }
 
     /**
-     * @param int|string $id
+     * @param  int|string  $id
      */
     public function setWorkflowId($id)
     {
@@ -102,7 +102,7 @@ public function setWorkflowId($id)
     }
 
     /**
-     * @param string $name
+     * @param  string  $name
      */
     public function setWorkflowName($name)
     {
@@ -110,24 +110,24 @@ public function setWorkflowName($name)
     }
 
     /**
-     * @param string $id
-     * @param string $participant
-     * @param string $name
+     * @param  string  $id
+     * @param  string  $participant
+     * @param  string  $name
      */
     public function addEndEvent($id, $participant, $name = null)
     {
-        $this->endEvents[$id] = array($participant, $name);
+        $this->endEvents[$id] = [$participant, $name];
     }
 
     /**
-     * @param int|string $id
-     * @param string     $participant
-     * @param string     $name
-     * @param int|string $defaultSequenceFlow
+     * @param  int|string  $id
+     * @param  string  $participant
+     * @param  string  $name
+     * @param  int|string  $defaultSequenceFlow
      */
     public function addExclusiveGateway($id, $participant, $name = null, $defaultSequenceFlow = null)
     {
-        $this->exclusiveGateways[$id] = array($participant, $name);
+        $this->exclusiveGateways[$id] = [$participant, $name];
 
         if ($defaultSequenceFlow !== null) {
             $this->defaultableFlowObjects[$defaultSequenceFlow] = $id;
@@ -135,20 +135,20 @@ public function addExclusiveGateway($id, $participant, $name = null, $defaultSeq
     }
 
     /**
-     * @param int|string $id
-     * @param string     $name
+     * @param  int|string  $id
+     * @param  string  $name
      */
     public function addRole($id, $name = null)
     {
-        $this->roles[$id] = array($name);
+        $this->roles[$id] = [$name];
     }
 
     /**
-     * @param string     $source
-     * @param string     $destination
-     * @param int|string $id
-     * @param string     $name
-     * @param string     $condition
+     * @param  string  $source
+     * @param  string  $destination
+     * @param  int|string  $id
+     * @param  string  $name
+     * @param  string  $condition
      */
     public function addSequenceFlow($source, $destination, $id = null, $name = null, $condition = null)
     {
@@ -156,21 +156,21 @@ public function addSequenceFlow($source, $destination, $id = null, $name = null,
 
         if ($id === null) {
             $id = $source.'.'.$destination.$i;
-            ++$i;
+            $i++;
         }
 
-        $this->sequenceFlows[$id] = array($source, $destination, $name, $condition);
+        $this->sequenceFlows[$id] = [$source, $destination, $name, $condition];
     }
 
     /**
-     * @param int|string $id
-     * @param string     $participant
-     * @param string     $name
-     * @param int|string $defaultSequenceFlow
+     * @param  int|string  $id
+     * @param  string  $participant
+     * @param  string  $name
+     * @param  int|string  $defaultSequenceFlow
      */
     public function addStartEvent($id, $participant, $name = null, $defaultSequenceFlow = null)
     {
-        $this->startEvents[$id] = array($participant, $name, $defaultSequenceFlow);
+        $this->startEvents[$id] = [$participant, $name, $defaultSequenceFlow];
 
         if ($defaultSequenceFlow !== null) {
             $this->defaultableFlowObjects[$defaultSequenceFlow] = $id;
@@ -178,14 +178,14 @@ public function addStartEvent($id, $participant, $name = null, $defaultSequenceF
     }
 
     /**
-     * @param string     $id
-     * @param string     $participant
-     * @param string     $name
-     * @param int|string $defaultSequenceFlow
+     * @param  string  $id
+     * @param  string  $participant
+     * @param  string  $name
+     * @param  int|string  $defaultSequenceFlow
      */
     public function addTask($id, $participant, $name = null, $defaultSequenceFlow = null)
     {
-        $this->tasks[$id] = array($participant, $name);
+        $this->tasks[$id] = [$participant, $name];
 
         if ($defaultSequenceFlow !== null) {
             $this->defaultableFlowObjects[$defaultSequenceFlow] = $id;
@@ -193,17 +193,17 @@ public function addTask($id, $participant, $name = null, $defaultSequenceFlow =
     }
 
     /**
-     * @param string     $id
-     * @param string     $participant
-     * @param string     $operation
-     * @param string     $name
-     * @param int|string $defaultSequenceFlow
+     * @param  string  $id
+     * @param  string  $participant
+     * @param  string  $operation
+     * @param  string  $name
+     * @param  int|string  $defaultSequenceFlow
      *
      * @since Method available since Release 1.2.0
      */
     public function addServiceTask($id, $participant, $operation, $name = null, $defaultSequenceFlow = null)
     {
-        $this->serviceTasks[$id] = array($participant, $operation, $name);
+        $this->serviceTasks[$id] = [$participant, $operation, $name];
 
         if ($defaultSequenceFlow !== null) {
             $this->defaultableFlowObjects[$defaultSequenceFlow] = $id;
@@ -211,18 +211,18 @@ public function addServiceTask($id, $participant, $operation, $name = null, $def
     }
 
     /**
-     * @param string     $id
-     * @param string     $participant
-     * @param string     $message
-     * @param string     $operation
-     * @param string     $name
-     * @param int|string $defaultSequenceFlow
+     * @param  string  $id
+     * @param  string  $participant
+     * @param  string  $message
+     * @param  string  $operation
+     * @param  string  $name
+     * @param  int|string  $defaultSequenceFlow
      *
      * @since Method available since Release 1.3.0
      */
     public function addSendTask($id, $participant, $message, $operation, $name = null, $defaultSequenceFlow = null)
     {
-        $this->sendTasks[$id] = array($participant, $message, $operation, $name);
+        $this->sendTasks[$id] = [$participant, $message, $operation, $name];
 
         if ($defaultSequenceFlow !== null) {
             $this->defaultableFlowObjects[$defaultSequenceFlow] = $id;
@@ -239,54 +239,54 @@ public function build()
         $workflow = new Workflow($this->workflowId, $this->workflowName);
 
         foreach ($this->roles as $id => $role) {
-            list($name) = $role;
+            [$name] = $role;
             $workflow->addRole(new Role($id, $name));
         }
 
         foreach ($this->startEvents as $id => $event) {
-            list($roleId, $name) = $event;
+            [$roleId, $name] = $event;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new StartEvent($id, $workflow->getRole($roleId), $name));
         }
 
         foreach ($this->endEvents as $id => $event) {
-            list($roleId, $name) = $event;
+            [$roleId, $name] = $event;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new EndEvent($id, $workflow->getRole($roleId), $name));
         }
 
         foreach ($this->tasks as $id => $task) {
-            list($roleId, $name) = $task;
+            [$roleId, $name] = $task;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new Task($id, $workflow->getRole($roleId), $name));
         }
 
         foreach ($this->serviceTasks as $id => $task) {
-            list($roleId, $operation, $name) = $task;
+            [$roleId, $operation, $name] = $task;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new ServiceTask($id, $workflow->getRole($roleId), $operation, $name));
         }
 
         foreach ($this->sendTasks as $id => $task) {
-            list($roleId, $message, $operation, $name) = $task;
+            [$roleId, $message, $operation, $name] = $task;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new SendTask($id, $workflow->getRole($roleId), $message, $operation, $name));
         }
 
         foreach ($this->exclusiveGateways as $id => $gateway) {
-            list($roleId, $name) = $gateway;
+            [$roleId, $name] = $gateway;
             $this->assertWorkflowHasRole($workflow, $roleId);
 
             $workflow->addFlowObject(new ExclusiveGateway($id, $workflow->getRole($roleId), $name));
         }
 
         foreach ($this->sequenceFlows as $id => $flow) {
-            list($source, $destination, $name, $condition) = $flow;
+            [$source, $destination, $name, $condition] = $flow;
 
             if (array_key_exists($id, $this->defaultableFlowObjects) && $condition !== null) {
                 throw new \LogicException(sprintf('The sequence flow "%s" has the condition "%s". A condition cannot be set to the default sequence flow.', $id, $condition));
@@ -303,14 +303,14 @@ public function build()
     }
 
     /**
-     * @param Workflow   $workflow
-     * @param int|string $roleId
+     * @param  Workflow  $workflow
+     * @param  int|string  $roleId
      *
      * @throws \LogicException
      */
     private function assertWorkflowHasRole(Workflow $workflow, $roleId)
     {
-        if (!$workflow->hasRole($roleId)) {
+        if (! $workflow->hasRole($roleId)) {
             throw new \LogicException(sprintf('The workflow "%s" does not have the role "%s".', $workflow->getId(), $roleId));
         }
     }
diff --git a/src/Workflow/WorkflowRepositoryInterface.php b/src/Workflow/WorkflowRepositoryInterface.php
index 53f8fed..6c84e58 100644
--- a/src/Workflow/WorkflowRepositoryInterface.php
+++ b/src/Workflow/WorkflowRepositoryInterface.php
@@ -17,8 +17,7 @@
 interface WorkflowRepositoryInterface extends RepositoryInterface
 {
     /**
-     * @param int|string $id
-     *
+     * @param  int|string  $id
      * @return Workflow
      */
     public function findById($id);
diff --git a/tests/Definition/Bpmn2ReaderTest.php b/tests/Definition/Bpmn2ReaderTest.php
index bb52231..1448f64 100644
--- a/tests/Definition/Bpmn2ReaderTest.php
+++ b/tests/Definition/Bpmn2ReaderTest.php
@@ -13,8 +13,9 @@
 namespace PHPMentors\Workflower\Definition;
 
 use PHPMentors\Workflower\Workflow\WorkflowRepository;
+use PHPUnit\Framework\TestCase;
 
-class Bpmn2ReaderTest extends \PHPUnit_Framework_TestCase
+class Bpmn2ReaderTest extends TestCase
 {
     /**
      * @test
diff --git a/tests/Workflow/WorkflowRepository.php b/tests/Workflow/WorkflowRepository.php
index 5c7fdcd..9a65b75 100644
--- a/tests/Workflow/WorkflowRepository.php
+++ b/tests/Workflow/WorkflowRepository.php
@@ -20,7 +20,7 @@ class WorkflowRepository implements WorkflowRepositoryInterface
     /**
      * @var array
      */
-    private $workflows = array();
+    private $workflows = [];
 
     public function __construct()
     {
@@ -54,7 +54,7 @@ public function remove(EntityInterface $entity)
      */
     public function findById($id)
     {
-        if (!array_key_exists($id, $this->workflows)) {
+        if (! array_key_exists($id, $this->workflows)) {
             return null;
         }
 
diff --git a/tests/Workflow/WorkflowTest.php b/tests/Workflow/WorkflowTest.php
index 03b9a19..fac3d9f 100644
--- a/tests/Workflow/WorkflowTest.php
+++ b/tests/Workflow/WorkflowTest.php
@@ -16,8 +16,9 @@
 use PHPMentors\Workflower\Workflow\Activity\WorkItem;
 use PHPMentors\Workflower\Workflow\Activity\WorkItemInterface;
 use PHPMentors\Workflower\Workflow\Operation\OperationalInterface;
+use PHPUnit\Framework\TestCase;
 
-class WorkflowTest extends \PHPUnit_Framework_TestCase
+class WorkflowTest extends TestCase
 {
     /**
      * @var WorkflowRepositoryInterface
@@ -27,7 +28,7 @@ class WorkflowTest extends \PHPUnit_Framework_TestCase
     /**
      * {@inheritdoc}
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->workflowRepository = new WorkflowRepository();
     }
@@ -149,15 +150,15 @@ public function completeWorkItem()
      */
     public function completeActivityOnConditionalSequenceFlowsData()
     {
-        return array(
-            array(true, 'End'),
-            array(false, 'LoanStudy'),
-        );
+        return [
+            [true, 'End'],
+            [false, 'LoanStudy'],
+        ];
     }
 
     /**
-     * @param bool   $rejected
-     * @param string $nextFlowObjectId
+     * @param  bool  $rejected
+     * @param  string  $nextFlowObjectId
      *
      * @test
      * @dataProvider completeActivityOnConditionalSequenceFlowsData
@@ -168,7 +169,7 @@ public function completeActivityOnConditionalSequenceFlow($rejected, $nextFlowOb
         \Phake::when($participant)->hasRole($this->anything())->thenReturn(true);
 
         $workflow = $this->workflowRepository->findById('LoanRequestProcess');
-        $workflow->setProcessData(array('rejected' => false));
+        $workflow->setProcessData(['rejected' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
@@ -177,7 +178,7 @@ public function completeActivityOnConditionalSequenceFlow($rejected, $nextFlowOb
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
         $workflow->startWorkItem($workflow->getCurrentFlowObject(), $participant);
-        $workflow->setProcessData(array('rejected' => $rejected));
+        $workflow->setProcessData(['rejected' => $rejected]);
         $workflow->completeWorkItem($workflow->getCurrentFlowObject(), $participant);
 
         $currentFlowObject = $workflow->getCurrentFlowObject();
@@ -190,15 +191,15 @@ public function completeActivityOnConditionalSequenceFlow($rejected, $nextFlowOb
      */
     public function selectSequenceFlowOnExclusiveGatewayData()
     {
-        return array(
-            array(true, 'InformRejection'),
-            array(false, 'Disbursement'),
-        );
+        return [
+            [true, 'InformRejection'],
+            [false, 'Disbursement'],
+        ];
     }
 
     /**
-     * @param bool   $rejected
-     * @param string $nextFlowObjectId
+     * @param  bool  $rejected
+     * @param  string  $nextFlowObjectId
      *
      * @test
      * @dataProvider selectSequenceFlowOnExclusiveGatewayData
@@ -209,7 +210,7 @@ public function selectSequenceFlowOnExclusiveGateway($rejected, $nextFlowObjectI
         \Phake::when($participant)->hasRole($this->anything())->thenReturn(true);
 
         $workflow = $this->workflowRepository->findById('LoanRequestProcess');
-        $workflow->setProcessData(array('rejected' => false));
+        $workflow->setProcessData(['rejected' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
@@ -222,7 +223,7 @@ public function selectSequenceFlowOnExclusiveGateway($rejected, $nextFlowObjectI
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
         $workflow->startWorkItem($workflow->getCurrentFlowObject(), $participant);
-        $workflow->setProcessData(array('rejected' => $rejected));
+        $workflow->setProcessData(['rejected' => $rejected]);
         $workflow->completeWorkItem($workflow->getCurrentFlowObject(), $participant);
 
         $currentFlowObject = $workflow->getCurrentFlowObject();
@@ -239,7 +240,7 @@ public function end()
         \Phake::when($participant)->hasRole($this->anything())->thenReturn(true);
 
         $workflow = $this->workflowRepository->findById('LoanRequestProcess');
-        $workflow->setProcessData(array('rejected' => false));
+        $workflow->setProcessData(['rejected' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
@@ -283,7 +284,7 @@ public function getActivityLog()
         \Phake::when($participant)->hasRole($this->anything())->thenReturn(true);
 
         $workflow = $this->workflowRepository->findById('LoanRequestProcess');
-        $workflow->setProcessData(array('rejected' => false));
+        $workflow->setProcessData(['rejected' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
@@ -307,12 +308,12 @@ public function getActivityLog()
         $this->assertThat($activityLog, $this->isInstanceOf('PHPMentors\Workflower\Workflow\ActivityLogCollection'));
         $this->assertThat(count($activityLog), $this->equalTo(4));
 
-        $activityIds = array(
+        $activityIds = [
             'RecordLoanApplicationInformation',
             'CheckApplicantInformation',
             'LoanStudy',
             'Disbursement',
-        );
+        ];
 
         foreach ($activityLog as $i => $activityLogEntry) { /* @var $activityLogEntry ActivityLog */
             $this->assertThat($activityLogEntry->getActivity()->getId(), $this->equalTo($activityIds[$i]));
@@ -336,7 +337,7 @@ public function getActivityLogWithMultipleExecutionsOfSameActivity()
         \Phake::when($participant)->hasRole($this->anything())->thenReturn(true);
 
         $workflow = $this->workflowRepository->findById('MultipleWorkItemsProcess');
-        $workflow->setProcessData(array('satisfied' => false));
+        $workflow->setProcessData(['satisfied' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
@@ -353,7 +354,7 @@ public function getActivityLogWithMultipleExecutionsOfSameActivity()
 
         $workflow->allocateWorkItem($workflow->getCurrentFlowObject(), $participant);
         $workflow->startWorkItem($workflow->getCurrentFlowObject(), $participant);
-        $workflow->setProcessData(array('satisfied' => true));
+        $workflow->setProcessData(['satisfied' => true]);
         $workflow->completeWorkItem($workflow->getCurrentFlowObject(), $participant);
 
         $activityLog = $workflow->getActivityLog();
@@ -384,8 +385,11 @@ public function injectExpressionLanguage()
         $workflow = $this->workflowRepository->findById('LoanRequestProcess');
         $workflow->setExpressionLanguage($expressionLanguage);
 
-        $workflow->setProcessData(array('rejected' => false));
+        $workflow->setProcessData(['rejected' => false]);
         $workflow->start($workflow->getFlowObject('Start'));
+
+        // if not will get an error: this test did not perform any assertions
+        $this->assertTrue(true);
     }
 
     /**
@@ -403,7 +407,7 @@ public function executeServiceTasks()
         \Phake::when($operationRunner)->run($this->anything(), $this->anything())->thenReturnCallback(function (OperationalInterface $operational, Workflow $workflow) use ($self) {
             static $calls = 0;
 
-            ++$calls;
+            $calls++;
             $self->assertThat($operational, $self->isInstanceOf('PHPMentors\Workflower\Workflow\Activity\ServiceTask'));
             $self->assertThat($operational->getOperation(), $self->equalTo('phpmentors_workflower.service'.$calls));
         });
@@ -453,7 +457,7 @@ public function executeSendTasks()
         \Phake::when($operationRunner)->run($this->anything(), $this->anything())->thenReturnCallback(function (OperationalInterface $operational, Workflow $workflow) use ($self) {
             static $calls = 0;
 
-            ++$calls;
+            $calls++;
             $self->assertThat($operational, $self->isInstanceOf('PHPMentors\Workflower\Workflow\Activity\SendTask'));
             $self->assertThat($operational->getOperation(), $self->equalTo('phpmentors_workflower.service'.$calls));
             $self->assertThat($operational, $self->isInstanceOf('PHPMentors\Workflower\Workflow\Resource\MessageInterface'));