diff --git a/composer.json b/composer.json
index 87f7eeee..edf7dbdc 100644
--- a/composer.json
+++ b/composer.json
@@ -16,6 +16,7 @@
     ],
     "require" : {
         "php" : ">=7.2",
+        "ext-pdo": "*",
         "ext-pdo_sqlite": "*",
         "php-di/php-di": "^6.0",
         "psr/container": "^1.0",
diff --git a/src/Application.php b/src/Application.php
index 4fd93ab8..7cdc923e 100644
--- a/src/Application.php
+++ b/src/Application.php
@@ -4,13 +4,18 @@
 
 namespace PhpSchool\PhpWorkshop;
 
+use DI\Container;
 use DI\ContainerBuilder;
 use PhpSchool\PhpWorkshop\Check\CheckRepository;
 use PhpSchool\PhpWorkshop\Exception\InvalidArgumentException;
 use PhpSchool\PhpWorkshop\Exception\MissingArgumentException;
-use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
 use PhpSchool\PhpWorkshop\Factory\ResultRendererFactory;
 use PhpSchool\PhpWorkshop\Output\OutputInterface;
+use RuntimeException;
+
+use function class_exists;
+use function is_file;
+use function sprintf;
 
 /**
  * This is the main application class, this takes care of bootstrapping, routing and
@@ -46,7 +51,7 @@ final class Application
     /**
      * @var string|null
      */
-    private $logo = null;
+    private $logo;
 
     /**
      * @var string
@@ -72,8 +77,8 @@ final class Application
      */
     public function __construct(string $workshopTitle, string $diConfigFile)
     {
-        if (!\is_file($diConfigFile)) {
-            throw new InvalidArgumentException(\sprintf('File "%s" was expected to exist.', $diConfigFile));
+        if (!is_file($diConfigFile)) {
+            throw new InvalidArgumentException(sprintf('File "%s" was expected to exist.', $diConfigFile));
         }
 
         $this->workshopTitle = $workshopTitle;
@@ -108,12 +113,12 @@ public function addExercise(string $exercise): void
      */
     public function addResult(string $resultClass, string $resultRendererClass): void
     {
-        if (!\class_exists($resultClass)) {
-            throw new InvalidArgumentException(\sprintf('Class "%s" does not exist', $resultClass));
+        if (!class_exists($resultClass)) {
+            throw new InvalidArgumentException(sprintf('Class "%s" does not exist', $resultClass));
         }
 
-        if (!\class_exists($resultRendererClass)) {
-            throw new InvalidArgumentException(\sprintf('Class "%s" does not exist', $resultRendererClass));
+        if (!class_exists($resultRendererClass)) {
+            throw new InvalidArgumentException(sprintf('Class "%s" does not exist', $resultRendererClass));
         }
 
         $this->results[] = [
@@ -167,7 +172,7 @@ public function run(): int
 
         foreach ($this->exercises as $exercise) {
             if (false === $container->has($exercise)) {
-                throw new \RuntimeException(
+                throw new RuntimeException(
                     sprintf('No DI config found for exercise: "%s". Register a factory.', $exercise)
                 );
             }
@@ -176,7 +181,7 @@ public function run(): int
         $checkRepository = $container->get(CheckRepository::class);
         foreach ($this->checks as $check) {
             if (false === $container->has($check)) {
-                throw new \RuntimeException(
+                throw new RuntimeException(
                     sprintf('No DI config found for check: "%s". Register a factory.', $check)
                 );
             }
@@ -206,7 +211,7 @@ public function run(): int
                     )
                 );
             return 1;
-        } catch (\RuntimeException $e) {
+        } catch (RuntimeException $e) {
             $container
                 ->get(OutputInterface::class)
                 ->printError(
@@ -221,9 +226,9 @@ public function run(): int
     }
 
     /**
-     * @return \DI\Container
+     * @return Container
      */
-    private function getContainer(): \DI\Container
+    private function getContainer(): Container
     {
         $containerBuilder = new ContainerBuilder();
         $containerBuilder->addDefinitions(
diff --git a/src/Check/CodeParseCheck.php b/src/Check/CodeParseCheck.php
index b697889f..670ec1b1 100644
--- a/src/Check/CodeParseCheck.php
+++ b/src/Check/CodeParseCheck.php
@@ -5,8 +5,6 @@
 namespace PhpSchool\PhpWorkshop\Check;
 
 use PhpParser\Error;
-use PhpParser\Node\Expr\FuncCall;
-use PhpParser\NodeTraverser;
 use PhpParser\Parser;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseType;
@@ -66,6 +64,8 @@ public function check(ExerciseInterface $exercise, Input $input): ResultInterfac
 
     /**
      * This check can run on any exercise type.
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool
     {
diff --git a/src/Check/ComposerCheck.php b/src/Check/ComposerCheck.php
index 3b663853..81318156 100644
--- a/src/Check/ComposerCheck.php
+++ b/src/Check/ComposerCheck.php
@@ -4,6 +4,7 @@
 
 namespace PhpSchool\PhpWorkshop\Check;
 
+use InvalidArgumentException;
 use PhpSchool\PhpWorkshop\ComposerUtil\LockFileParser;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseType;
@@ -35,11 +36,12 @@ public function getName(): string
      * @param ExerciseInterface $exercise The exercise to check against.
      * @param Input $input The command line arguments passed to the command.
      * @return ResultInterface The result of the check.
+     * @noinspection SpellCheckingInspection
      */
     public function check(ExerciseInterface $exercise, Input $input): ResultInterface
     {
         if (!$exercise instanceof ComposerExerciseCheck) {
-            throw new \InvalidArgumentException();
+            throw new InvalidArgumentException();
         }
 
         if (!file_exists(sprintf('%s/composer.json', dirname($input->getRequiredArgument('program'))))) {
@@ -74,6 +76,9 @@ public function check(ExerciseInterface $exercise, Input $input): ResultInterfac
 
     /**
      * This check can run on any exercise type.
+     *
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool
     {
diff --git a/src/Check/DatabaseCheck.php b/src/Check/DatabaseCheck.php
index 29de3f68..2eba2878 100644
--- a/src/Check/DatabaseCheck.php
+++ b/src/Check/DatabaseCheck.php
@@ -5,6 +5,7 @@
 namespace PhpSchool\PhpWorkshop\Check;
 
 use PDO;
+use PDOException;
 use PhpSchool\PhpWorkshop\Event\CliExecuteEvent;
 use PhpSchool\PhpWorkshop\Event\Event;
 use PhpSchool\PhpWorkshop\Event\EventDispatcher;
@@ -12,6 +13,7 @@
 use PhpSchool\PhpWorkshop\ExerciseCheck\DatabaseExerciseCheck;
 use PhpSchool\PhpWorkshop\Result\Failure;
 use PhpSchool\PhpWorkshop\Result\Success;
+use RuntimeException;
 
 /**
  * This check sets up a database and a `PDO` object. It prepends the database DSN as a CLI argument to the student's
@@ -75,12 +77,14 @@ public function getExerciseInterface(): string
 
     /**
      * Here we attach to various events to seed, verify and inject the DSN's
-     * to the student & reference solution programs's CLI arguments.
+     * to the student & reference solution programs' CLI arguments.
+     *
+     * @param EventDispatcher $eventDispatcher
      */
     public function attach(EventDispatcher $eventDispatcher): void
     {
         if (file_exists($this->databaseDirectory)) {
-            throw new \RuntimeException(
+            throw new RuntimeException(
                 sprintf('Database directory: "%s" already exists', $this->databaseDirectory)
             );
         }
@@ -90,7 +94,7 @@ public function attach(EventDispatcher $eventDispatcher): void
         try {
             $db = new PDO($this->userDsn);
             $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
-        } catch (\PDOException $e) {
+        } catch (PDOException $e) {
             rmdir($this->databaseDirectory);
             throw $e;
         }
@@ -132,7 +136,7 @@ function (CliExecuteEvent $e) {
                 'verify.finish',
                 'run.finish'
             ],
-            function (Event $e) use ($db) {
+            function () use ($db) {
                 unset($db);
                 @unlink($this->userDatabasePath);
                 @unlink($this->solutionDatabasePath);
diff --git a/src/Check/FileExistsCheck.php b/src/Check/FileExistsCheck.php
index ff0952b9..5dba56e8 100644
--- a/src/Check/FileExistsCheck.php
+++ b/src/Check/FileExistsCheck.php
@@ -45,6 +45,9 @@ public function check(ExerciseInterface $exercise, Input $input): ResultInterfac
 
     /**
      * This check can run on any exercise type.
+     *
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool
     {
@@ -57,7 +60,7 @@ public function getExerciseInterface(): string
     }
 
     /**
-     * This check must run before executing the solution becuase it may not exist.
+     * This check must run before executing the solution because it may not exist.
      */
     public function getPosition(): string
     {
diff --git a/src/Check/FunctionRequirementsCheck.php b/src/Check/FunctionRequirementsCheck.php
index 2684b5d9..4c14f851 100644
--- a/src/Check/FunctionRequirementsCheck.php
+++ b/src/Check/FunctionRequirementsCheck.php
@@ -4,9 +4,9 @@
 
 namespace PhpSchool\PhpWorkshop\Check;
 
+use InvalidArgumentException;
 use PhpParser\Error;
 use PhpParser\Node\Expr\FuncCall;
-use PhpParser\Node\Name;
 use PhpParser\NodeTraverser;
 use PhpParser\Parser;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
@@ -18,7 +18,6 @@
 use PhpSchool\PhpWorkshop\Result\FunctionRequirementsFailure;
 use PhpSchool\PhpWorkshop\Result\ResultInterface;
 use PhpSchool\PhpWorkshop\Result\Success;
-use PhpSchool\PhpWorkshop\Utils\Collection;
 
 /**
  * This check verifies that the student's solution contains usages of some required functions
@@ -59,7 +58,7 @@ public function getName(): string
     public function check(ExerciseInterface $exercise, Input $input): ResultInterface
     {
         if (!$exercise instanceof FunctionRequirementsExerciseCheck) {
-            throw new \InvalidArgumentException();
+            throw new InvalidArgumentException();
         }
 
         $requiredFunctions  = $exercise->getRequiredFunctions();
@@ -100,6 +99,9 @@ public function check(ExerciseInterface $exercise, Input $input): ResultInterfac
 
     /**
      * This check can run on any exercise type.
+     *
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool
     {
diff --git a/src/Check/ListenableCheckInterface.php b/src/Check/ListenableCheckInterface.php
index 8995b72d..ac517530 100644
--- a/src/Check/ListenableCheckInterface.php
+++ b/src/Check/ListenableCheckInterface.php
@@ -14,6 +14,8 @@ interface ListenableCheckInterface extends CheckInterface
     /**
      * Attach to events throughout the running/verifying process. Inject verifiers
      * and listeners.
+     *
+     * @param EventDispatcher $eventDispatcher
      */
     public function attach(EventDispatcher $eventDispatcher): void;
 }
diff --git a/src/Check/PhpLintCheck.php b/src/Check/PhpLintCheck.php
index 9d148251..17c8984f 100644
--- a/src/Check/PhpLintCheck.php
+++ b/src/Check/PhpLintCheck.php
@@ -47,6 +47,9 @@ public function check(ExerciseInterface $exercise, Input $input): ResultInterfac
 
     /**
      * This check can run on any exercise type.
+     *
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool
     {
diff --git a/src/Check/SimpleCheckInterface.php b/src/Check/SimpleCheckInterface.php
index af72aa9a..5b4bf78a 100644
--- a/src/Check/SimpleCheckInterface.php
+++ b/src/Check/SimpleCheckInterface.php
@@ -31,6 +31,9 @@ interface SimpleCheckInterface extends CheckInterface
 
     /**
      * Can this check run this exercise?
+     *
+     * @param ExerciseType $exerciseType
+     * @return bool
      */
     public function canRun(ExerciseType $exerciseType): bool;
 
diff --git a/src/Command/PrintCommand.php b/src/Command/PrintCommand.php
index 7e63bb58..89a7a429 100644
--- a/src/Command/PrintCommand.php
+++ b/src/Command/PrintCommand.php
@@ -4,7 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\Command;
 
-use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
 use PhpSchool\PhpWorkshop\ExerciseRepository;
 use PhpSchool\PhpWorkshop\MarkdownRenderer;
 use PhpSchool\PhpWorkshop\Output\OutputInterface;
diff --git a/src/Command/VerifyCommand.php b/src/Command/VerifyCommand.php
index 416c0799..f99c15fa 100644
--- a/src/Command/VerifyCommand.php
+++ b/src/Command/VerifyCommand.php
@@ -6,7 +6,6 @@
 
 use PhpSchool\PhpWorkshop\ExerciseDispatcher;
 use PhpSchool\PhpWorkshop\ExerciseRepository;
-use PhpSchool\PhpWorkshop\ExerciseRunner;
 use PhpSchool\PhpWorkshop\Input\Input;
 use PhpSchool\PhpWorkshop\Output\OutputInterface;
 use PhpSchool\PhpWorkshop\ResultRenderer\ResultsRenderer;
diff --git a/src/CommandRouter.php b/src/CommandRouter.php
index c86a3b20..168f2dec 100644
--- a/src/CommandRouter.php
+++ b/src/CommandRouter.php
@@ -4,11 +4,13 @@
 
 namespace PhpSchool\PhpWorkshop;
 
+use InvalidArgumentException;
 use PhpSchool\PhpWorkshop\Event\EventDispatcher;
 use PhpSchool\PhpWorkshop\Exception\CliRouteNotExistsException;
 use PhpSchool\PhpWorkshop\Exception\MissingArgumentException;
 use Psr\Container\ContainerInterface;
 use PhpSchool\PhpWorkshop\Input\Input;
+use RuntimeException;
 
 /**
  * Parses $argv (or passed array) and attempts to find a command
@@ -60,7 +62,7 @@ public function __construct(
         }
 
         if (!isset($this->commands[$default])) {
-            throw new \InvalidArgumentException(sprintf('Default command: "%s" is not available', $default));
+            throw new InvalidArgumentException(sprintf('Default command: "%s" is not available', $default));
         }
         $this->defaultCommand = $default;
         $this->eventDispatcher = $eventDispatcher;
@@ -73,7 +75,7 @@ public function __construct(
     private function addCommand(CommandDefinition $c): void
     {
         if (isset($this->commands[$c->getName()])) {
-            throw new \InvalidArgumentException(sprintf('Command with name: "%s" already exists', $c->getName()));
+            throw new InvalidArgumentException(sprintf('Command with name: "%s" already exists', $c->getName()));
         }
 
         $this->commands[$c->getName()] = $c;
@@ -100,7 +102,7 @@ public function route(array $args = null): int
     {
 
         if (null === $args) {
-            $args = isset($_SERVER['argv']) ? $_SERVER['argv'] : [];
+            $args = $_SERVER['argv'] ?? [];
         }
 
         $appName = array_shift($args);
@@ -196,17 +198,17 @@ private function resolveCallable(CommandDefinition $command, Input $input): int
         }
 
         if (!is_string($commandCallable)) {
-            throw new \RuntimeException('Callable must be a callable or a container entry for a callable service');
+            throw new RuntimeException('Callable must be a callable or a container entry for a callable service');
         }
 
         if (!$this->container->has($commandCallable)) {
-            throw new \RuntimeException(sprintf('Container has no entry named: "%s"', $commandCallable));
+            throw new RuntimeException(sprintf('Container has no entry named: "%s"', $commandCallable));
         }
 
         $callable = $this->container->get($commandCallable);
 
         if (!is_callable($callable)) {
-            throw new \RuntimeException(sprintf('Container entry: "%s" not callable', $commandCallable));
+            throw new RuntimeException(sprintf('Container entry: "%s" not callable', $commandCallable));
         }
 
         $return = $this->callCommand($command, $callable, $input);
diff --git a/src/ComposerUtil/LockFileParser.php b/src/ComposerUtil/LockFileParser.php
index d6b14d26..afb63593 100644
--- a/src/ComposerUtil/LockFileParser.php
+++ b/src/ComposerUtil/LockFileParser.php
@@ -61,7 +61,7 @@ public function getInstalledPackages(): array
      * @param string $packageName
      * @return bool
      */
-    public function hasInstalledPackage($packageName): bool
+    public function hasInstalledPackage(string $packageName): bool
     {
         foreach ($this->contents['packages'] as $packageDetails) {
             if ($packageName === $packageDetails['name']) {
diff --git a/src/Event/EventDispatcher.php b/src/Event/EventDispatcher.php
index dfacca14..8999e526 100644
--- a/src/Event/EventDispatcher.php
+++ b/src/Event/EventDispatcher.php
@@ -94,8 +94,6 @@ public function insertVerifier(string $eventName, callable $verifier): void
             //return type hints pls
             if ($result instanceof ResultInterface) {
                 $this->resultAggregator->add($result);
-            } else {
-                //??!!
             }
         });
     }
diff --git a/src/Exception/ExerciseNotAssignedException.php b/src/Exception/ExerciseNotAssignedException.php
index 490276f9..80cd5e41 100644
--- a/src/Exception/ExerciseNotAssignedException.php
+++ b/src/Exception/ExerciseNotAssignedException.php
@@ -4,10 +4,12 @@
 
 namespace PhpSchool\PhpWorkshop\Exception;
 
+use RuntimeException;
+
 /**
  * When a student has no exercise assigned
  */
-class ExerciseNotAssignedException extends \RuntimeException
+class ExerciseNotAssignedException extends RuntimeException
 {
     /**
      * @return self
diff --git a/src/Exception/InvalidArgumentException.php b/src/Exception/InvalidArgumentException.php
index 038f389a..4804e51d 100644
--- a/src/Exception/InvalidArgumentException.php
+++ b/src/Exception/InvalidArgumentException.php
@@ -52,7 +52,7 @@ public static function notValidParameter(string $parameterName, array $allowedVa
      * @param class-string $requiredInterface
      * @return self
      */
-    public static function missingImplements($object, string $requiredInterface): self
+    public static function missingImplements(object $object, string $requiredInterface): self
     {
         return new self(
             sprintf(
diff --git a/src/Exception/MissingArgumentException.php b/src/Exception/MissingArgumentException.php
index 552d5e72..d4dbcc65 100644
--- a/src/Exception/MissingArgumentException.php
+++ b/src/Exception/MissingArgumentException.php
@@ -14,7 +14,7 @@ class MissingArgumentException extends RuntimeException
     /**
      * @var array<string>
      */
-    private $missingArguments = [];
+    private $missingArguments;
 
     /**
      * Create the exception, requires the command name and missing arguments.
diff --git a/src/Exercise/ExerciseInterface.php b/src/Exercise/ExerciseInterface.php
index fb3e8fc8..e636fbeb 100644
--- a/src/Exercise/ExerciseInterface.php
+++ b/src/Exercise/ExerciseInterface.php
@@ -5,7 +5,6 @@
 namespace PhpSchool\PhpWorkshop\Exercise;
 
 use PhpSchool\PhpWorkshop\ExerciseDispatcher;
-use PhpSchool\PhpWorkshop\Solution\SolutionInterface;
 
 /**
  * This interface describes all of the methods an exercise
diff --git a/src/ExerciseDispatcher.php b/src/ExerciseDispatcher.php
index 77230edc..4dbc6d3c 100644
--- a/src/ExerciseDispatcher.php
+++ b/src/ExerciseDispatcher.php
@@ -4,11 +4,9 @@
 
 namespace PhpSchool\PhpWorkshop;
 
-use PhpSchool\PhpWorkshop\Check\CheckInterface;
 use PhpSchool\PhpWorkshop\Check\CheckRepository;
 use PhpSchool\PhpWorkshop\Check\ListenableCheckInterface;
 use PhpSchool\PhpWorkshop\Check\SimpleCheckInterface;
-use PhpSchool\PhpWorkshop\Event\Event;
 use PhpSchool\PhpWorkshop\Event\EventDispatcher;
 use PhpSchool\PhpWorkshop\Event\ExerciseRunnerEvent;
 use PhpSchool\PhpWorkshop\Exception\CheckNotApplicableException;
diff --git a/src/ExerciseRenderer.php b/src/ExerciseRenderer.php
index f578945b..6b1ffe3d 100644
--- a/src/ExerciseRenderer.php
+++ b/src/ExerciseRenderer.php
@@ -59,7 +59,7 @@ class ExerciseRenderer
      * @param OutputInterface $output
      */
     public function __construct(
-        $appName,
+        string $appName,
         ExerciseRepository $exerciseRepository,
         UserState $userState,
         UserStateSerializer $userStateSerializer,
@@ -91,7 +91,7 @@ public function __invoke(CliMenu $menu): void
         $this->userStateSerializer->serialize($this->userState);
 
         $numExercises = count($exercises);
-        $exerciseIndex = ((int) array_search($exercise, $exercises)) + 1;
+        $exerciseIndex = ((int) array_search($exercise, $exercises, true)) + 1;
 
         $output  = "\n";
         $output .= $this->color->__invoke(' LEARN YOU THE PHP FOR MUCH WIN! ')->magenta()->bold() . "\n";
diff --git a/src/ExerciseRunner/CgiRunner.php b/src/ExerciseRunner/CgiRunner.php
index 9a8eb9f4..c5fd6305 100644
--- a/src/ExerciseRunner/CgiRunner.php
+++ b/src/ExerciseRunner/CgiRunner.php
@@ -28,7 +28,6 @@
 use Psr\Http\Message\ResponseInterface;
 use RuntimeException;
 use Symfony\Component\Process\Process;
-use Zend\Diactoros\Response\Serializer as ResponseSerializer;
 
 /**
  * The `CGI` runner. This runner executes solutions as if they were behind a web-server. They populate the `$_SERVER`,
@@ -74,9 +73,9 @@ public function __construct(
         EventDispatcher $eventDispatcher,
         RequestRenderer $requestRenderer
     ) {
-        if (strpos(PHP_OS, 'WIN') !== false) {
+        if (PHP_OS_FAMILY === 'Windows') {
             // Check if in path. 2> nul > nul equivalent to 2>&1 /dev/null
-            $silence  = (PHP_OS == 'CYGWIN' ? '> /dev/null 2>&1' : '2> nul > nul');
+            $silence  = (PHP_OS === 'CYGWIN' ? '> /dev/null 2>&1' : '2> nul > nul');
             system(sprintf('php-cgi --version %s', $silence), $failedToRun);
             if ($failedToRun) {
                 $newPath = realpath(sprintf('%s/%s', dirname(PHP_BINARY), 'php-cgi.exe'));
diff --git a/src/ExerciseRunner/ExerciseRunnerInterface.php b/src/ExerciseRunner/ExerciseRunnerInterface.php
index 42dbb023..66acec07 100644
--- a/src/ExerciseRunner/ExerciseRunnerInterface.php
+++ b/src/ExerciseRunner/ExerciseRunnerInterface.php
@@ -4,8 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\ExerciseRunner;
 
-use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
-use PhpSchool\PhpWorkshop\ExerciseDispatcher;
 use PhpSchool\PhpWorkshop\Input\Input;
 use PhpSchool\PhpWorkshop\Output\OutputInterface;
 use PhpSchool\PhpWorkshop\Result\ResultInterface;
diff --git a/src/Factory/ResultRendererFactory.php b/src/Factory/ResultRendererFactory.php
index 10109a90..f1776d52 100644
--- a/src/Factory/ResultRendererFactory.php
+++ b/src/Factory/ResultRendererFactory.php
@@ -7,6 +7,7 @@
 use PhpSchool\PhpWorkshop\Exception\InvalidArgumentException;
 use PhpSchool\PhpWorkshop\Result\ResultInterface;
 use PhpSchool\PhpWorkshop\ResultRenderer\ResultRendererInterface;
+use RuntimeException;
 
 /**
  * Manages and creates renderers for results
@@ -53,7 +54,7 @@ public function create(ResultInterface $result): ResultRendererInterface
     {
         $class = get_class($result);
         if (!isset($this->mappings[$class])) {
-            throw new \RuntimeException(sprintf('No renderer found for "%s"', $class));
+            throw new RuntimeException(sprintf('No renderer found for "%s"', $class));
         }
 
         $class = $this->mappings[$class];
@@ -62,7 +63,7 @@ public function create(ResultInterface $result): ResultRendererInterface
         $renderer = $factory($result);
 
         if (!$renderer instanceof $class) {
-            throw new \RuntimeException(
+            throw new RuntimeException(
                 sprintf(
                     'Renderer Factory for "%s" produced "%s" instead of expected "%s"',
                     $class,
diff --git a/src/Input/Input.php b/src/Input/Input.php
index 4d0a0d81..a811f6fe 100644
--- a/src/Input/Input.php
+++ b/src/Input/Input.php
@@ -4,7 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\Input;
 
-use PhpSchool\PhpWorkshop\CommandDefinition;
 use PhpSchool\PhpWorkshop\Exception\InvalidArgumentException;
 
 /**
@@ -20,7 +19,7 @@ class Input
     /**
      * @var array<string, string|null>
      */
-    private $arguments = [];
+    private $arguments;
 
     /**
      * @param string $appName
diff --git a/src/Listener/CheckExerciseAssignedListener.php b/src/Listener/CheckExerciseAssignedListener.php
index 4389dcd4..670bb60f 100644
--- a/src/Listener/CheckExerciseAssignedListener.php
+++ b/src/Listener/CheckExerciseAssignedListener.php
@@ -7,6 +7,7 @@
 use PhpSchool\PhpWorkshop\CommandDefinition;
 use PhpSchool\PhpWorkshop\Event\Event;
 use PhpSchool\PhpWorkshop\UserState;
+use RuntimeException;
 
 class CheckExerciseAssignedListener
 {
@@ -36,7 +37,7 @@ public function __invoke(Event $event): void
         }
 
         if (!$this->userState->isAssignedExercise()) {
-            throw new \RuntimeException('No active exercise. Select one from the menu');
+            throw new RuntimeException('No active exercise. Select one from the menu');
         }
     }
 }
diff --git a/src/Listener/CodePatchListener.php b/src/Listener/CodePatchListener.php
index 26d44ed4..a1266167 100644
--- a/src/Listener/CodePatchListener.php
+++ b/src/Listener/CodePatchListener.php
@@ -5,9 +5,7 @@
 namespace PhpSchool\PhpWorkshop\Listener;
 
 use PhpSchool\PhpWorkshop\CodePatcher;
-use PhpSchool\PhpWorkshop\Event\Event;
 use PhpSchool\PhpWorkshop\Event\ExerciseRunnerEvent;
-use PhpSchool\PhpWorkshop\Input\Input;
 use RuntimeException;
 
 /**
diff --git a/src/Listener/RealPathListener.php b/src/Listener/RealPathListener.php
index 6a8be51a..4bee01c1 100644
--- a/src/Listener/RealPathListener.php
+++ b/src/Listener/RealPathListener.php
@@ -4,11 +4,7 @@
 
 namespace PhpSchool\PhpWorkshop\Listener;
 
-use PhpSchool\PhpWorkshop\CommandDefinition;
-use PhpSchool\PhpWorkshop\Event\Event;
 use PhpSchool\PhpWorkshop\Event\ExerciseRunnerEvent;
-use PhpSchool\PhpWorkshop\Input\Input;
-use PhpSchool\PhpWorkshop\UserState;
 
 /**
  * Replace program arg with absolute path
diff --git a/src/NodeVisitor/FunctionVisitor.php b/src/NodeVisitor/FunctionVisitor.php
index e2c5d03b..975bf378 100644
--- a/src/NodeVisitor/FunctionVisitor.php
+++ b/src/NodeVisitor/FunctionVisitor.php
@@ -44,6 +44,7 @@ public function __construct(array $requiredFunctions, array $bannedFunctions)
 
     /**
      * @param Node $node
+     * @return null
      */
     public function leaveNode(Node $node)
     {
diff --git a/src/Output/OutputInterface.php b/src/Output/OutputInterface.php
index 5bcf1433..745055b3 100644
--- a/src/Output/OutputInterface.php
+++ b/src/Output/OutputInterface.php
@@ -4,8 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\Output;
 
-use Psr\Http\Message\RequestInterface;
-
 /**
  * Output interface
  */
diff --git a/src/Output/StdOutput.php b/src/Output/StdOutput.php
index f2d61f12..2bc15178 100644
--- a/src/Output/StdOutput.php
+++ b/src/Output/StdOutput.php
@@ -13,7 +13,7 @@
 class StdOutput implements OutputInterface
 {
     /**
-     * @var \Colors\Color
+     * @var Color
      */
     private $color;
 
diff --git a/src/Result/Cgi/CgiResult.php b/src/Result/Cgi/CgiResult.php
index 151ff7f7..7661aad9 100644
--- a/src/Result/Cgi/CgiResult.php
+++ b/src/Result/Cgi/CgiResult.php
@@ -6,7 +6,6 @@
 
 use ArrayIterator;
 use IteratorAggregate;
-use PhpSchool\PhpWorkshop\Result\Cgi\ResultInterface;
 use PhpSchool\PhpWorkshop\Result\ResultGroupInterface;
 
 /**
diff --git a/src/Result/Cgi/Success.php b/src/Result/Cgi/Success.php
index df92a327..e2428604 100644
--- a/src/Result/Cgi/Success.php
+++ b/src/Result/Cgi/Success.php
@@ -4,7 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\Result\Cgi;
 
-use PhpSchool\PhpWorkshop\Check\CheckInterface;
 use Psr\Http\Message\RequestInterface;
 
 /**
diff --git a/src/ResultAggregator.php b/src/ResultAggregator.php
index c73407da..c750b82d 100644
--- a/src/ResultAggregator.php
+++ b/src/ResultAggregator.php
@@ -5,7 +5,6 @@
 namespace PhpSchool\PhpWorkshop;
 
 use ArrayIterator;
-use Countable;
 use IteratorAggregate;
 use PhpSchool\PhpWorkshop\Result\FailureInterface;
 use PhpSchool\PhpWorkshop\Result\ResultGroupInterface;
diff --git a/src/ResultRenderer/ComparisonFailureRenderer.php b/src/ResultRenderer/ComparisonFailureRenderer.php
index e0c39d23..b6559e31 100644
--- a/src/ResultRenderer/ComparisonFailureRenderer.php
+++ b/src/ResultRenderer/ComparisonFailureRenderer.php
@@ -4,7 +4,6 @@
 
 namespace PhpSchool\PhpWorkshop\ResultRenderer;
 
-use PhpSchool\PhpWorkshop\Result\Cli\RequestFailure;
 use PhpSchool\PhpWorkshop\Result\ComparisonFailure;
 
 /**
diff --git a/src/ResultRenderer/ResultsRenderer.php b/src/ResultRenderer/ResultsRenderer.php
index 2aff91ba..02dd5250 100644
--- a/src/ResultRenderer/ResultsRenderer.php
+++ b/src/ResultRenderer/ResultsRenderer.php
@@ -7,7 +7,6 @@
 use Colors\Color;
 use Kadet\Highlighter\Formatter\CliFormatter;
 use Kadet\Highlighter\KeyLighter;
-use PhpSchool\PhpWorkshop\Result\FailureInterface;
 use PhpSchool\Terminal\Terminal;
 use PhpSchool\CliMenu\Util\StringUtil;
 use PhpSchool\PhpWorkshop\Exercise\ProvidesSolution;
@@ -20,9 +19,12 @@
 use PhpSchool\PhpWorkshop\Result\ResultInterface;
 use PhpSchool\PhpWorkshop\ResultAggregator;
 use PhpSchool\PhpWorkshop\UserState;
+use PhpSchool\PhpWorkshop\Result\FailureInterface;
+
+use function mb_str_pad;
 
 /**
- * Renderer which renders a `PhpSchool\PhpWorkshop\ResultAggregator` and writes it to x§the output.
+ * Renderer which renders a `PhpSchool\PhpWorkshop\ResultAggregator` and writes it to the output.
  */
 class ResultsRenderer
 {
@@ -145,7 +147,7 @@ private function renderErrorInformation(
     ): void {
         foreach ($failures as [$failure, $message]) {
             $output->writeLine($this->center($this->style(str_repeat(' ', $padLength), ['bg_red'])));
-            $output->writeLine($this->center($this->style(\mb_str_pad($message, $padLength), ['bg_red'])));
+            $output->writeLine($this->center($this->style(mb_str_pad($message, $padLength), ['bg_red'])));
             $output->writeLine($this->center($this->style(str_repeat(' ', $padLength), ['bg_red'])));
 
             $output->emptyLine();
diff --git a/src/Solution/DirectorySolution.php b/src/Solution/DirectorySolution.php
index ae4b4597..b67b55fe 100644
--- a/src/Solution/DirectorySolution.php
+++ b/src/Solution/DirectorySolution.php
@@ -8,6 +8,7 @@
 use RecursiveCallbackFilterIterator;
 use RecursiveDirectoryIterator;
 use RecursiveIteratorIterator;
+use SplFileInfo;
 
 /**
  * Solution which can contain multiple files, the file to execute is defined as the entry point.
@@ -22,7 +23,7 @@ class DirectorySolution implements SolutionInterface
     /**
      * @var array<SolutionFile>
      */
-    private $files = [];
+    private $files;
 
     /**
      * @var string
@@ -46,7 +47,7 @@ public function __construct(string $directory, string $entryPoint, array $exclus
 
         $dir  = new RecursiveDirectoryIterator($directory, RecursiveDirectoryIterator::SKIP_DOTS);
         $iter = new RecursiveIteratorIterator(
-            new RecursiveCallbackFilterIterator($dir, function (\SplFileInfo $current) use ($exclusions) {
+            new RecursiveCallbackFilterIterator($dir, function (SplFileInfo $current) use ($exclusions) {
                 return !in_array($current->getBasename(), $exclusions, true);
             }),
             RecursiveIteratorIterator::SELF_FIRST
diff --git a/src/UserStateSerializer.php b/src/UserStateSerializer.php
index ab9efce8..5133fd31 100644
--- a/src/UserStateSerializer.php
+++ b/src/UserStateSerializer.php
@@ -151,7 +151,7 @@ private function migrateData(string $legacySaveFile): ?UserState
         }
 
         //lets check if the data is in the old format
-        if (!isset($data['completed_exercises']) || !isset($data['current_exercise'])) {
+        if (!isset($data['completed_exercises'], $data['current_exercise'])) {
             unlink($legacySaveFile);
             return null;
         }
@@ -162,7 +162,7 @@ private function migrateData(string $legacySaveFile): ?UserState
         //check to see if this old data represents THIS workshop
         //if not we bail
         foreach ($completedExercises as $completedExercise) {
-            if (!in_array($completedExercise, $availableExercises)) {
+            if (!in_array($completedExercise, $availableExercises, true)) {
                 return null;
             }
         }
diff --git a/src/Utils/ArrayObject.php b/src/Utils/ArrayObject.php
index 52595e3f..26acd2c6 100644
--- a/src/Utils/ArrayObject.php
+++ b/src/Utils/ArrayObject.php
@@ -149,11 +149,7 @@ public function append($value): self
      */
     public function get(string $key, $default = null)
     {
-        if (isset($this->array[$key])) {
-            return $this->array[$key];
-        }
-
-        return $default;
+        return $this->array[$key] ?? $default;
     }
 
     /**