diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0e3c218..2015c21 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -8,8 +8,8 @@ jobs:
 
     strategy:
       matrix:
-        php: [5.6, 7.0, 7.1, 7.2, 7.3, 7.4, 8.0]
-    
+        php: [7.4, 8.0]
+
     steps:
     - name: Checkout code
       uses: actions/checkout@v2
diff --git a/composer.json b/composer.json
index d685201..797298a 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
     "name":"codeception/module-rest",
     "description":"REST module for Codeception",
     "keywords":["codeception", "rest"],
-    "homepage":"http://codeception.com/",
+    "homepage":"https://codeception.com/",
     "type":"library",
     "license":"MIT",
     "authors":[
@@ -12,12 +12,15 @@
     ],
     "minimum-stability": "RC",
     "require": {
-        "php": ">=5.6.6 <9.0",
-        "softcreatr/jsonpath": "^0.5 || ^0.7",
+        "php": "^7.4 | ^8.0",
+        "ext-dom": "*",
+        "ext-json": "*",
         "codeception/codeception": "^4.0",
-        "justinrainbow/json-schema": "~5.2.9"
+        "justinrainbow/json-schema": "~5.2.9",
+        "softcreatr/jsonpath": "^0.5 | ^0.7"
     },
     "require-dev": {
+        "codeception/stub": "^3.7",
         "codeception/util-universalframework": "^1.0",
         "codeception/lib-innerbrowser": "^1.0"
     },
diff --git a/readme.md b/readme.md
index 9d1118a..84e9168 100644
--- a/readme.md
+++ b/readme.md
@@ -7,6 +7,10 @@ A REST module for Codeception
 [![Total Downloads](https://poser.pugx.org/codeception/module-rest/downloads)](https://packagist.org/packages/codeception/module-rest)
 [![License](https://poser.pugx.org/codeception/module-rest/license)](/LICENSE)
 
+## Requirements
+
+* `PHP 7.4` or higher.
+
 ## Installation
 
 ```
diff --git a/src/Codeception/Module/REST.php b/src/Codeception/Module/REST.php
index 3d5898d..1c715f2 100644
--- a/src/Codeception/Module/REST.php
+++ b/src/Codeception/Module/REST.php
@@ -1,26 +1,36 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Codeception\Module;
 
+use ArrayAccess;
 use Codeception\Exception\ConfigurationException;
+use Codeception\Exception\ExternalUrlException;
 use Codeception\Exception\ModuleConfigException;
 use Codeception\Exception\ModuleException;
-use Codeception\Lib\Interfaces\ConflictsWithModule;
-use Codeception\Module as CodeceptionModule;
-use Codeception\PHPUnit\Constraint\JsonContains;
-use Codeception\PHPUnit\Constraint\JsonType as JsonTypeConstraint;
-use Codeception\TestInterface;
-use Codeception\Lib\Interfaces\API;
 use Codeception\Lib\Framework;
 use Codeception\Lib\InnerBrowser;
+use Codeception\Lib\Interfaces\API;
+use Codeception\Lib\Interfaces\ConflictsWithModule;
 use Codeception\Lib\Interfaces\DependsOnModule;
 use Codeception\Lib\Interfaces\PartedModule;
+use Codeception\Module;
+use Codeception\PHPUnit\Constraint\JsonContains;
+use Codeception\PHPUnit\Constraint\JsonType as JsonTypeConstraint;
+use Codeception\TestInterface;
 use Codeception\Util\JsonArray;
 use Codeception\Util\JsonType;
-use Codeception\Util\XmlStructure;
 use Codeception\Util\Soap as XmlUtils;
+use Codeception\Util\XmlStructure;
+use Exception;
+use JsonException;
+use JsonSchema\Constraints\Constraint as JsonConstraint;
 use JsonSchema\Validator as JsonSchemaValidator;
-use JsonSchema\Constraints\Constraint as JsonContraint;
+use JsonSerializable;
+use PHPUnit\Framework\Assert;
+use Symfony\Component\BrowserKit\AbstractBrowser;
+use Symfony\Component\HttpKernel\HttpKernelBrowser;
 
 /**
  * Module for testing REST WebService.
@@ -81,16 +91,22 @@
  * Conflicts with SOAP module
  *
  */
-class REST extends CodeceptionModule implements DependsOnModule, PartedModule, API, ConflictsWithModule
+class REST extends Module implements DependsOnModule, PartedModule, API, ConflictsWithModule
 {
-    const QUERY_PARAMS_AWARE_METHODS = ['GET', 'HEAD', 'OPTIONS'];
+    /**
+     * @var string[]
+     */
+    public const QUERY_PARAMS_AWARE_METHODS = ['GET', 'HEAD', 'OPTIONS'];
 
+    /**
+     * @var array<string, string>
+     */
     protected $config = [
         'url' => '',
         'aws' => ''
     ];
 
-    protected $dependencyMessage = <<<EOF
+    protected string $dependencyMessage = <<<EOF
 Example configuring PhpBrowser as backend for REST module.
 --
 modules:
@@ -103,45 +119,48 @@ class REST extends CodeceptionModule implements DependsOnModule, PartedModule, A
 Framework modules can be used for testing of API as well.
 EOF;
 
-    protected $DEFAULT_SHORTEN_VALUE = 150;
+    protected int $DEFAULT_SHORTEN_VALUE = 150;
 
     /**
-     * @var \Symfony\Component\HttpKernel\HttpKernelBrowser|\Symfony\Component\BrowserKit\AbstractBrowser
+     * @var HttpKernelBrowser|AbstractBrowser
      */
-    public $client = null;
-    public $isFunctional = false;
+    public $client;
 
-    /**
-     * @var InnerBrowser
-     */
-    protected $connectionModule;
+    public bool $isFunctional = false;
+
+    protected ?InnerBrowser $connectionModule = null;
 
+    /** @var array */
     public $params = [];
-    public $response = "";
 
-    public function _before(TestInterface $test)
+    public ?string $response = null;
+
+    public function _before(TestInterface $test): void
     {
         $this->client = &$this->connectionModule->client;
         $this->resetVariables();
     }
 
-    protected function resetVariables()
+    protected function resetVariables(): void
     {
         $this->params = [];
-        $this->response = "";
+        $this->response = '';
         $this->connectionModule->headers = [];
     }
 
     public function _conflicts()
     {
-        return 'Codeception\Lib\Interfaces\API';
+        return \Codeception\Lib\Interfaces\API::class;
     }
 
     public function _depends()
     {
-        return ['Codeception\Lib\InnerBrowser' => $this->dependencyMessage];
+        return [InnerBrowser::class => $this->dependencyMessage];
     }
 
+    /**
+     * @return string[]
+     */
     public function _parts()
     {
         return ['xml', 'json'];
@@ -153,31 +172,32 @@ public function _inject(InnerBrowser $connection)
         if ($this->connectionModule instanceof Framework) {
             $this->isFunctional = true;
         }
-        if ($this->connectionModule instanceof PhpBrowser) {
-            if (!$this->connectionModule->_getConfig('url')) {
-                $this->connectionModule->_setConfig(['url' => $this->config['url']]);
-            }
+
+        if ($this->connectionModule instanceof PhpBrowser && !$this->connectionModule->_getConfig('url')) {
+            $this->connectionModule->_setConfig(['url' => $this->config['url']]);
         }
     }
 
     public function _failed(TestInterface $test, $fail)
     {
-        if (!$this->response) {
+        if ($this->response === '' || $this->response === '0') {
             return;
         }
+
         $printedResponse = $this->response;
         if ($this->isBinaryData($printedResponse)) {
             $printedResponse = $this->binaryToDebugString($printedResponse);
         }
+
         $test->getMetadata()->addReport('body', $printedResponse);
     }
 
-
-    protected function getRunningClient()
+    protected function getRunningClient(): AbstractBrowser
     {
         if ($this->client->getInternalRequest() === null) {
             throw new ModuleException($this, "Response is empty. Use `\$I->sendXXX()` methods to send HTTP request");
         }
+
         return $this->client;
     }
 
@@ -188,15 +208,12 @@ protected function getRunningClient()
      * <?php
      * $I->haveHttpHeader('Content-Type', 'application/json');
      * // all next requests will contain this header
-     * ?>
      * ```
      *
-     * @param $name
-     * @param $value
      * @part json
      * @part xml
      */
-    public function haveHttpHeader($name, $value)
+    public function haveHttpHeader(string $name, string $value): void
     {
         $this->connectionModule->haveHttpHeader($name, $value);
     }
@@ -213,14 +230,13 @@ public function haveHttpHeader($name, $value)
      * // ...
      * $I->deleteHeader('X-Requested-With');
      * $I->sendPost('some-other-page.php');
-     * ?>
      * ```
      *
      * @param string $name the name of the header to delete.
      * @part json
      * @part xml
      */
-    public function deleteHeader($name)
+    public function deleteHeader(string $name): void
     {
         $this->connectionModule->deleteHeader($name);
     }
@@ -229,20 +245,21 @@ public function deleteHeader($name)
      * Checks over the given HTTP header and (optionally)
      * its value, asserting that are there
      *
-     * @param $name
+     * @param string $name
      * @param $value
      * @part json
      * @part xml
      */
-    public function seeHttpHeader($name, $value = null)
+    public function seeHttpHeader(string $name, $value = null): void
     {
         if ($value !== null) {
-            $this->assertEquals(
+            $this->assertSame(
                 $value,
                 $this->getRunningClient()->getInternalResponse()->getHeader($name)
             );
             return;
         }
+
         $this->assertNotNull($this->getRunningClient()->getInternalResponse()->getHeader($name));
     }
 
@@ -250,12 +267,12 @@ public function seeHttpHeader($name, $value = null)
      * Checks over the given HTTP header and (optionally)
      * its value, asserting that are not there
      *
-     * @param $name
+     * @param string $name
      * @param $value
      * @part json
      * @part xml
      */
-    public function dontSeeHttpHeader($name, $value = null)
+    public function dontSeeHttpHeader(string $name, $value = null): void
     {
         if ($value !== null) {
             $this->assertNotEquals(
@@ -264,6 +281,7 @@ public function dontSeeHttpHeader($name, $value = null)
             );
             return;
         }
+
         $this->assertNull($this->getRunningClient()->getInternalResponse()->getHeader($name));
     }
 
@@ -275,14 +293,13 @@ public function dontSeeHttpHeader($name, $value = null)
      * ``` php
      * <?php
      * $I->seeHttpHeaderOnce('Cache-Control');
-     * ?>>
      * ```
      *
-     * @param $name
+     * @param string $name
      * @part json
      * @part xml
      */
-    public function seeHttpHeaderOnce($name)
+    public function seeHttpHeaderOnce(string $name): void
     {
         $headers = $this->getRunningClient()->getInternalResponse()->getHeader($name, false);
         $this->assertCount(1, $headers);
@@ -291,14 +308,12 @@ public function seeHttpHeaderOnce($name)
     /**
      * Returns the value of the specified header name
      *
-     * @param $name
-     * @param Boolean $first Whether to return the first value or all header values
-     *
+     * @param bool $first Whether to return the first value or all header values
      * @return string|array The first header value if $first is true, an array of values otherwise
      * @part json
      * @part xml
      */
-    public function grabHttpHeader($name, $first = true)
+    public function grabHttpHeader(string $name, bool $first = true)
     {
         return $this->getRunningClient()->getInternalResponse()->getHeader($name, $first);
     }
@@ -306,12 +321,10 @@ public function grabHttpHeader($name, $first = true)
     /**
      * Adds HTTP authentication via username/password.
      *
-     * @param $username
-     * @param $password
      * @part json
      * @part xml
      */
-    public function amHttpAuthenticated($username, $password)
+    public function amHttpAuthenticated(string $username, string $password): void
     {
         if ($this->isFunctional) {
             $this->client->setServerParameter('PHP_AUTH_USER', $username);
@@ -324,27 +337,25 @@ public function amHttpAuthenticated($username, $password)
     /**
      * Adds Digest authentication via username/password.
      *
-     * @param $username
-     * @param $password
      * @part json
      * @part xml
      */
-    public function amDigestAuthenticated($username, $password)
+    public function amDigestAuthenticated(string $username, string $password): void
     {
         if ($this->isFunctional) {
             throw new ModuleException(__METHOD__, 'Not supported by functional modules');
         }
+
         $this->client->setAuth($username, $password, 'digest');
     }
 
     /**
      * Adds Bearer authentication via access token.
      *
-     * @param $accessToken
      * @part json
      * @part xml
      */
-    public function amBearerAuthenticated($accessToken)
+    public function amBearerAuthenticated(string $accessToken): void
     {
         $this->haveHttpHeader('Authorization', 'Bearer ' . $accessToken);
     }
@@ -358,23 +369,22 @@ public function amBearerAuthenticated($accessToken)
      * ```php
      * <?php
      * $I->amNTLMAuthenticated('jon_snow', 'targaryen');
-     * ?>
      * ```
      *
-     * @param $username
-     * @param $password
      * @throws ModuleException
      * @part json
      * @part xml
      */
-    public function amNTLMAuthenticated($username, $password)
+    public function amNTLMAuthenticated(string $username, string $password): void
     {
         if ($this->isFunctional) {
             throw new ModuleException(__METHOD__, 'Not supported by functional modules');
         }
+
         if (!defined('\GuzzleHttp\Client::MAJOR_VERSION') && !defined('\GuzzleHttp\Client::VERSION')) {
             throw new ModuleException(__METHOD__, 'Not supported if not using a Guzzle client');
         }
+
         $this->client->setAuth($username, $password, 'ntlm');
     }
 
@@ -397,12 +407,11 @@ public function amNTLMAuthenticated($username, $password)
      * ```php
      * <?php
      * $I->amAWSAuthenticated();
-     * ?>
      * ```
      * @param array $additionalAWSConfig
      * @throws ConfigurationException
      */
-    public function amAWSAuthenticated($additionalAWSConfig = [])
+    public function amAWSAuthenticated(array $additionalAWSConfig = []): void
     {
         if (method_exists($this->client, 'setAwsAuth')) {
             $config = array_merge($this->config['aws'], $additionalAWSConfig);
@@ -410,12 +419,15 @@ public function amAWSAuthenticated($additionalAWSConfig = [])
             if (!isset($config['key'])) {
                 throw new ConfigurationException('AWS Key is not set');
             }
+
             if (!isset($config['secret'])) {
                 throw new ConfigurationException('AWS Secret is not set');
             }
+
             if (!isset($config['service'])) {
                 throw new ConfigurationException('AWS Service is not set');
             }
+
             if (!isset($config['region'])) {
                 throw new ConfigurationException('AWS Region is not set');
             }
@@ -452,8 +464,7 @@ public function amAWSAuthenticated($additionalAWSConfig = [])
      * ]]);
      * ```
      *
-     * @param $url
-     * @param array|string|\JsonSerializable $params
+     * @param array|string|JsonSerializable $params
      * @param array $files A list of filenames or "mocks" of $_FILES (each entry being an array with the following
      *                     keys: name, type, error, size, tmp_name (pointing to the real file path). Each key works
      *                     as the "name" attribute of a file input field.
@@ -463,7 +474,7 @@ public function amAWSAuthenticated($additionalAWSConfig = [])
      * @part json
      * @part xml
      */
-    public function sendPost($url, $params = [], $files = [])
+    public function sendPost(string $url, $params = [], array $files = [])
     {
         return $this->execute('POST', $url, $params, $files);
     }
@@ -471,12 +482,10 @@ public function sendPost($url, $params = [], $files = [])
     /**
      * Sends a HEAD request to given uri.
      *
-     * @param $url
-     * @param array $params
      * @part json
      * @part xml
      */
-    public function sendHead($url, $params = [])
+    public function sendHead(string $url, array $params = [])
     {
         return $this->execute('HEAD', $url, $params);
     }
@@ -484,12 +493,10 @@ public function sendHead($url, $params = [])
     /**
      * Sends an OPTIONS request to given uri.
      *
-     * @param $url
-     * @param array $params
      * @part json
      * @part xml
      */
-    public function sendOptions($url, $params = [])
+    public function sendOptions(string $url, array $params = []): void
     {
         $this->execute('OPTIONS', $url, $params);
     }
@@ -505,12 +512,10 @@ public function sendOptions($url, $params = [])
      * $I->sendGet('/orders', ['id' => 1])
      * ```
      *
-     * @param $url
-     * @param array $params
      * @part json
      * @part xml
      */
-    public function sendGet($url, $params = [])
+    public function sendGet(string $url, array $params = [])
     {
         return $this->execute('GET', $url, $params);
     }
@@ -523,13 +528,11 @@ public function sendGet($url, $params = [])
      * $response = $I->sendPut('/message/1', ['subject' => 'Read this!']);
      * ```
      *
-     * @param $url
      * @param array|string|\JsonSerializable $params
-     * @param array $files
      * @part json
      * @part xml
      */
-    public function sendPut($url, $params = [], $files = [])
+    public function sendPut(string $url, $params = [], array $files = [])
     {
         return $this->execute('PUT', $url, $params, $files);
     }
@@ -542,13 +545,11 @@ public function sendPut($url, $params = [], $files = [])
      * $response = $I->sendPatch('/message/1', ['subject' => 'Read this!']);
      * ```
      *
-     * @param       $url
      * @param array|string|\JsonSerializable $params
-     * @param array $files
      * @part json
      * @part xml
      */
-    public function sendPatch($url, $params = [], $files = [])
+    public function sendPatch(string $url, $params = [], array $files = [])
     {
         return $this->execute('PATCH', $url, $params, $files);
     }
@@ -560,15 +561,11 @@ public function sendPatch($url, $params = [], $files = [])
      * <?php
      * $I->sendDelete('/message/1');
      * ```
-
      *
-     * @param $url
-     * @param array $params
-     * @param array $files
      * @part json
      * @part xml
      */
-    public function sendDelete($url, $params = [], $files = [])
+    public function sendDelete(string $url, array $params = [], array $files = [])
     {
         return $this->execute('DELETE', $url, $params, $files);
     }
@@ -576,14 +573,11 @@ public function sendDelete($url, $params = [], $files = [])
     /**
      * Sends a HTTP request.
      *
-     * @param $method
-     * @param $url
-     * @param array|string|\JsonSerializable $params
-     * @param array $files
+     * @param array|string|JsonSerializable $params
      * @part json
      * @part xml
      */
-    public function send($method, $url, $params = [], $files = [])
+    public function send(string $method, string $url, $params = [], array $files = [])
     {
         return $this->execute(strtoupper($method), $url, $params, $files);
     }
@@ -597,16 +591,16 @@ public function send($method, $url, $params = [], $files = [])
      *
      * @author samva.ua@gmail.com
      */
-    private function setHeaderLink(array $linkEntries)
+    private function setHeaderLink(array $linkEntries): void
     {
         $values = [];
         foreach ($linkEntries as $linkEntry) {
-            \PHPUnit\Framework\Assert::assertArrayHasKey(
+            Assert::assertArrayHasKey(
                 'uri',
                 $linkEntry,
                 'linkEntry should contain property "uri"'
             );
-            \PHPUnit\Framework\Assert::assertArrayHasKey(
+            Assert::assertArrayHasKey(
                 'link-param',
                 $linkEntry,
                 'linkEntry should contain property "link-param"'
@@ -620,7 +614,6 @@ private function setHeaderLink(array $linkEntries)
     /**
      * Sends LINK request to given uri.
      *
-     * @param       $url
      * @param array $linkEntries (entry is array with keys "uri" and "link-param")
      *
      * @link http://tools.ietf.org/html/rfc2068#section-19.6.2.4
@@ -629,7 +622,7 @@ private function setHeaderLink(array $linkEntries)
      * @part json
      * @part xml
      */
-    public function sendLink($url, array $linkEntries)
+    public function sendLink(string $url, array $linkEntries): void
     {
         $this->setHeaderLink($linkEntries);
         $this->execute('LINK', $url);
@@ -638,19 +631,25 @@ public function sendLink($url, array $linkEntries)
     /**
      * Sends UNLINK request to given uri.
      *
-     * @param       $url
      * @param array $linkEntries (entry is array with keys "uri" and "link-param")
      * @link http://tools.ietf.org/html/rfc2068#section-19.6.2.4
      * @author samva.ua@gmail.com
      * @part json
      * @part xml
      */
-    public function sendUnlink($url, array $linkEntries)
+    public function sendUnlink(string $url, array $linkEntries): void
     {
         $this->setHeaderLink($linkEntries);
         $this->execute('UNLINK', $url);
     }
 
+    /**
+     * @param $method
+     * @param $url
+     * @param array|string|object $parameters
+     * @param array $files
+     * @throws ModuleException|ExternalUrlException|JsonException
+     */
     protected function execute($method, $url, $parameters = [], $files = [])
     {
         // allow full url to be requested
@@ -682,25 +681,32 @@ protected function execute($method, $url, $parameters = [], $files = [])
                     } else {
                         $url .= '?';
                     }
+
                     $url .= http_build_query($parameters);
                 }
-                $this->debugSection("Request", "$method $url");
+
+                $this->debugSection("Request", sprintf('%s %s', $method, $url));
                 $files = [];
             } else {
-                $this->debugSection("Request", "$method $url " . json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION));
+                $this->debugSection("Request",
+                    sprintf('%s %s ', $method, $url) . json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION | JSON_THROW_ON_ERROR)
+                );
                 $files = $this->formatFilesArray($files);
             }
-            $this->response = (string)$this->connectionModule->_request($method, $url, $parameters, $files);
+
+            $this->response = $this->connectionModule->_request($method, $url, $parameters, $files);
         } else {
             $requestData = $parameters;
             if ($this->isBinaryData($requestData)) {
                 $requestData = $this->binaryToDebugString($requestData);
             }
-            $this->debugSection("Request", "$method $url " . $requestData);
-            $this->response = (string)$this->connectionModule->_request($method, $url, [], $files, [], $parameters);
+
+            $this->debugSection("Request", sprintf('%s %s ', $method, $url) . $requestData);
+            $this->response = $this->connectionModule->_request($method, $url, [], $files, [], $parameters);
         }
+
         $printedResponse = $this->response;
-        if ($this->isBinaryData($printedResponse)) {
+        if ($this->isBinaryData((string) $printedResponse)) {
             $printedResponse = $this->binaryToDebugString($printedResponse);
         }
 
@@ -720,9 +726,8 @@ protected function execute($method, $url, $parameters = [], $files = [])
      * Check if data has non-printable bytes and it is not a valid unicode string
      *
      * @param string $data the text or binary data string
-     * @return boolean
      */
-    protected function isBinaryData($data)
+    protected function isBinaryData(string $data): bool
     {
         return !ctype_print($data) && false === mb_detect_encoding($data, mb_detect_order(), true);
     }
@@ -733,29 +738,30 @@ protected function isBinaryData($data)
      * @param string $data the binary data string
      * @return string the debug string
      */
-    protected function binaryToDebugString($data)
+    protected function binaryToDebugString(string $data): string
     {
         return '[binary-data length:' . strlen($data) . ' md5:' . md5($data) . ']';
     }
 
-    protected function encodeApplicationJson($method, $parameters)
+    protected function encodeApplicationJson(string $method, $parameters)
     {
         if (
             array_key_exists('Content-Type', $this->connectionModule->headers)
             && ($this->connectionModule->headers['Content-Type'] === 'application/json'
-                || preg_match('!^application/.+\+json$!', $this->connectionModule->headers['Content-Type'])
+                || preg_match('#^application/.+\+json$#', $this->connectionModule->headers['Content-Type'])
             )
         ) {
-            if ($parameters instanceof \JsonSerializable) {
-                return json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION);
+            if ($parameters instanceof JsonSerializable) {
+                return json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION | JSON_THROW_ON_ERROR);
             }
-            if (is_array($parameters) || $parameters instanceof \ArrayAccess) {
+
+            if (is_array($parameters) || $parameters instanceof ArrayAccess) {
                 $parameters = $this->scalarizeArray($parameters);
-                return json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION);
+                return json_encode($parameters, JSON_PRESERVE_ZERO_FRACTION | JSON_THROW_ON_ERROR);
             }
         }
 
-        if ($parameters instanceof \JsonSerializable) {
+        if ($parameters instanceof JsonSerializable) {
             throw new ModuleException(__CLASS__, $method . ' parameters is JsonSerializable object, but Content-Type header is not set to application/json');
         }
 
@@ -766,12 +772,11 @@ protected function encodeApplicationJson($method, $parameters)
         return $parameters;
     }
 
-    private function formatFilesArray(array $files)
+    private function formatFilesArray(array $files): array
     {
         foreach ($files as $name => $value) {
             if (is_string($value)) {
                 $this->checkFileBeforeUpload($value);
-
                 $files[$name] = [
                     'name' => basename($value),
                     'tmp_name' => $value,
@@ -780,18 +785,23 @@ private function formatFilesArray(array $files)
                     'error' => 0,
                 ];
                 continue;
-            } elseif (is_array($value)) {
+            }
+
+            if (is_array($value)) {
                 if (isset($value['tmp_name'])) {
                     $this->checkFileBeforeUpload($value['tmp_name']);
                     if (!isset($value['name'])) {
                         $value['name'] = basename($value['tmp_name']);
                     }
+
                     if (!isset($value['size'])) {
                         $value['size'] = filesize($value['tmp_name']);
                     }
+
                     if (!isset($value['type'])) {
                         $value['type'] = $this->getFileType($value['tmp_name']);
                     }
+
                     if (!isset($value['error'])) {
                         $value['error'] = 0;
                     }
@@ -804,31 +814,34 @@ private function formatFilesArray(array $files)
                  * @issue https://github.com/Codeception/Codeception/issues/3298
                  */
             } else {
-                throw new ModuleException(__CLASS__, "Invalid value of key $name in files array");
+                throw new ModuleException(__CLASS__, sprintf('Invalid value of key %s in files array', $name));
             }
         }
 
         return $files;
     }
 
-    private function getFileType($file)
+    private function getFileType($file): string
     {
         if (function_exists('mime_content_type') && mime_content_type($file)) {
             return mime_content_type($file);
         }
+
         return 'application/octet-stream';
     }
 
-    private function checkFileBeforeUpload($file)
+    private function checkFileBeforeUpload(string $file): void
     {
         if (!file_exists($file)) {
-            throw new ModuleException(__CLASS__, "File $file does not exist");
+            throw new ModuleException(__CLASS__, sprintf('File %s does not exist', $file));
         }
+
         if (!is_readable($file)) {
-            throw new ModuleException(__CLASS__, "File $file is not readable");
+            throw new ModuleException(__CLASS__, sprintf('File %s is not readable', $file));
         }
+
         if (!is_file($file)) {
-            throw new ModuleException(__CLASS__, "File $file is not a regular file");
+            throw new ModuleException(__CLASS__, sprintf('File %s is not a regular file', $file));
         }
     }
 
@@ -836,16 +849,14 @@ private function checkFileBeforeUpload($file)
      * Extends the function Module::validateConfig for shorten messages
      *
      */
-    protected function validateConfig()
+    protected function validateConfig(): void
     {
         parent::validateConfig();
 
         $short = $this->_getConfig('shortDebugResponse');
 
-        if (!is_null($short)) {
-            if (!is_int($short) || $short < 0) {
-                throw new ModuleConfigException(__CLASS__, 'The value of "shortDebugMessage" should be integer and greater or equal "0".');
-            }
+        if (!is_null($short) && (!is_int($short) || $short < 0)) {
+            throw new ModuleConfigException(__CLASS__, 'The value of "shortDebugMessage" should be integer and greater or equal "0".');
         }
     }
 
@@ -855,35 +866,33 @@ protected function validateConfig()
      *
      * @part json
      */
-    public function seeResponseIsJson()
+    public function seeResponseIsJson(): void
     {
         $responseContent = $this->connectionModule->_getResponseContent();
-        \PHPUnit\Framework\Assert::assertNotEquals('', $responseContent, 'response is empty');
+        Assert::assertNotEquals('', $responseContent, 'response is empty');
         $this->decodeAndValidateJson($responseContent);
     }
 
     /**
      * Checks whether the last response contains text.
      *
-     * @param $text
      * @part json
      * @part xml
      */
-    public function seeResponseContains($text)
+    public function seeResponseContains(string $text): void
     {
-        $this->assertStringContainsString($text, $this->connectionModule->_getResponseContent(), "REST response contains");
+        $this->assertStringContainsString($text, $this->connectionModule->_getResponseContent(), 'REST response contains');
     }
 
     /**
      * Checks whether last response do not contain text.
      *
-     * @param $text
      * @part json
      * @part xml
      */
-    public function dontSeeResponseContains($text)
+    public function dontSeeResponseContains(string $text): void
     {
-        $this->assertStringNotContainsString($text, $this->connectionModule->_getResponseContent(), "REST response contains");
+        $this->assertStringNotContainsString($text, $this->connectionModule->_getResponseContent(), 'REST response contains');
     }
 
     /**
@@ -902,17 +911,15 @@ public function dontSeeResponseContains($text)
      * // response {user: john, profile: { email: john@gmail.com }}
      * $I->seeResponseContainsJson(array('email' => 'john@gmail.com'));
      *
-     * ?>
      * ```
      *
      * This method recursively checks if one array can be found inside of another.
      *
-     * @param array $json
      * @part json
      */
-    public function seeResponseContainsJson($json = [])
+    public function seeResponseContainsJson(array $json = []): void
     {
-        \PHPUnit\Framework\Assert::assertThat(
+        Assert::assertThat(
             $this->connectionModule->_getResponseContent(),
             new JsonContains($json)
         );
@@ -940,30 +947,30 @@ public function seeResponseContainsJson($json = [])
      * ];
      * $I->seeResponseIsValidOnJsonSchemaString(json_encode($schema));
      *
-     * ?>
      * ```
      *
-     * @param string $schema
      * @part json
      */
-    public function seeResponseIsValidOnJsonSchemaString($schema)
+    public function seeResponseIsValidOnJsonSchemaString(string $schema): void
     {
         $responseContent = $this->connectionModule->_getResponseContent();
-        \PHPUnit\Framework\Assert::assertNotEquals('', $responseContent, 'response is empty');
+        Assert::assertNotEquals('', $responseContent, 'response is empty');
         $responseObject = $this->decodeAndValidateJson($responseContent);
 
-        \PHPUnit\Framework\Assert::assertNotEquals('', $schema, 'schema is empty');
+        Assert::assertNotEquals('', $schema, 'schema is empty');
         $schemaObject = $this->decodeAndValidateJson($schema, "Invalid schema json: %s. System message: %s.");
 
         $validator = new JsonSchemaValidator();
-        $validator->validate($responseObject, $schemaObject, JsonContraint::CHECK_MODE_VALIDATE_SCHEMA);
+        $validator->validate($responseObject, $schemaObject, JsonConstraint::CHECK_MODE_VALIDATE_SCHEMA);
+
         $outcome = $validator->isValid();
-        $error = "";
+        $error = '';
         if (!$outcome) {
             $errors = $validator->getErrors();
             $error = array_shift($errors)["message"];
         }
-        \PHPUnit\Framework\Assert::assertTrue(
+
+        Assert::assertTrue(
             $outcome,
             $error
         );
@@ -973,32 +980,32 @@ public function seeResponseIsValidOnJsonSchemaString($schema)
      * Checks whether last response matches the supplied json schema (https://json-schema.org/)
      * Supply schema as relative file path in your project directory or an absolute path
      *
-     * @see codecept_absolute_path()
-     *
      * @param string $schemaFilename
      * @part json
+     * @see codecept_absolute_path()
      */
-    public function seeResponseIsValidOnJsonSchema($schemaFilename)
+    public function seeResponseIsValidOnJsonSchema(string $schemaFilename): void
     {
         $file = codecept_absolute_path($schemaFilename);
         if (!file_exists($file)) {
-            throw new ModuleException(__CLASS__, "File $file does not exist");
+            throw new ModuleException(__CLASS__, sprintf('File %s does not exist', $file));
         }
+
         $this->seeResponseIsValidOnJsonSchemaString(file_get_contents($file));
     }
 
     /**
-     * Converts string to json and asserts that no error occured while decoding.
+     * Converts string to json and asserts that no error occurred while decoding.
      *
      * @param string $jsonString the json encoded string
      * @param string $errorFormat optional string for custom sprintf format
      */
-    protected function decodeAndValidateJson($jsonString, $errorFormat="Invalid json: %s. System message: %s.")
+    protected function decodeAndValidateJson(string $jsonString, string $errorFormat="Invalid json: %s. System message: %s.")
     {
         $json = json_decode($jsonString);
         $errorCode = json_last_error();
         $errorMessage = json_last_error_msg();
-        \PHPUnit\Framework\Assert::assertEquals(
+        Assert::assertSame(
             JSON_ERROR_NONE,
             $errorCode,
             sprintf(
@@ -1019,14 +1026,12 @@ protected function decodeAndValidateJson($jsonString, $errorFormat="Invalid json
      * <?php
      * $user_id = $I->grabResponse();
      * $I->sendPut('/user', array('id' => $user_id, 'name' => 'davert'));
-     * ?>
      * ```
      *
-     * @return string
      * @part json
      * @part xml
      */
-    public function grabResponse()
+    public function grabResponse(): string
     {
         return $this->connectionModule->_getResponseContent();
     }
@@ -1041,15 +1046,13 @@ public function grabResponse()
      * // match the first `user.id` in json
      * $firstUserId = $I->grabDataFromResponseByJsonPath('$..users[0].id');
      * $I->sendPut('/user', array('id' => $firstUserId[0], 'name' => 'davert'));
-     * ?>
      * ```
      *
-     * @param string $jsonPath
      * @return array Array of matching items
-     * @throws \Exception
+     * @throws Exception
      * @part json
      */
-    public function grabDataFromResponseByJsonPath($jsonPath)
+    public function grabDataFromResponseByJsonPath(string $jsonPath): array
     {
         return (new JsonArray($this->connectionModule->_getResponseContent()))->filterByJsonPath($jsonPath);
     }
@@ -1089,34 +1092,31 @@ public function grabDataFromResponseByJsonPath($jsonPath)
      * $I->seeResponseJsonMatchesXpath('//store/book[1]/author');
      * // at least one item in store has price
      * $I->seeResponseJsonMatchesXpath('/store//price');
-     * ?>
      * ```
-     * @param string $xpath
      * @part json
      */
-    public function seeResponseJsonMatchesXpath($xpath)
+    public function seeResponseJsonMatchesXpath(string $xPath): void
     {
         $response = $this->connectionModule->_getResponseContent();
         $this->assertGreaterThan(
             0,
-            (new JsonArray($response))->filterByXPath($xpath)->length,
-            "Received JSON did not match the XPath `$xpath`.\nJson Response: \n" . $response
+            (new JsonArray($response))->filterByXPath($xPath)->length,
+            "Received JSON did not match the XPath `{$xPath}`.\nJson Response: \n" . $response
         );
     }
 
     /**
      * Opposite to seeResponseJsonMatchesXpath
      *
-     * @param string $xpath
      * @part json
      */
-    public function dontSeeResponseJsonMatchesXpath($xpath)
+    public function dontSeeResponseJsonMatchesXpath(string $xPath): void
     {
         $response = $this->connectionModule->_getResponseContent();
-        $this->assertEquals(
+        $this->assertSame(
             0,
-            (new JsonArray($response))->filterByXPath($xpath)->length,
-            "Received JSON matched the XPath `$xpath`.\nJson Response: \n" . $response
+            (new JsonArray($response))->filterByXPath($xPath)->length,
+            "Received JSON matched the XPath `{$xPath}`.\nJson Response: \n" . $response
         );
     }
 
@@ -1154,18 +1154,16 @@ public function dontSeeResponseJsonMatchesXpath($xpath)
      * $I->seeResponseJsonMatchesJsonPath('$.store.book[0].author');
      * // at least one item in store has price
      * $I->seeResponseJsonMatchesJsonPath('$.store..price');
-     * ?>
      * ```
      *
-     * @param string $jsonPath
      * @part json
      */
-    public function seeResponseJsonMatchesJsonPath($jsonPath)
+    public function seeResponseJsonMatchesJsonPath(string $jsonPath): void
     {
         $response = $this->connectionModule->_getResponseContent();
         $this->assertNotEmpty(
             (new JsonArray($response))->filterByJsonPath($jsonPath),
-            "Received JSON did not match the JsonPath `$jsonPath`.\nJson Response: \n" . $response
+            "Received JSON did not match the JsonPath `{$jsonPath}`.\nJson Response: \n" . $response
         );
     }
 
@@ -1173,15 +1171,14 @@ public function seeResponseJsonMatchesJsonPath($jsonPath)
      * See [#jsonpath](#jsonpath) for general info on JSONPath.
      * Opposite to [`seeResponseJsonMatchesJsonPath()`](#seeResponseJsonMatchesJsonPath)
      *
-     * @param string $jsonPath
      * @part json
      */
-    public function dontSeeResponseJsonMatchesJsonPath($jsonPath)
+    public function dontSeeResponseJsonMatchesJsonPath(string $jsonPath): void
     {
         $response = $this->connectionModule->_getResponseContent();
         $this->assertEmpty(
             (new JsonArray($response))->filterByJsonPath($jsonPath),
-            "Received JSON matched the JsonPath `$jsonPath`.\nJson Response: \n" . $response
+            "Received JSON matched the JsonPath `{$jsonPath}`.\nJson Response: \n" . $response
         );
     }
 
@@ -1189,9 +1186,8 @@ public function dontSeeResponseJsonMatchesJsonPath($jsonPath)
      * Opposite to seeResponseContainsJson
      *
      * @part json
-     * @param array $json
      */
-    public function dontSeeResponseContainsJson($json = [])
+    public function dontSeeResponseContainsJson(array $json = []): void
     {
         $jsonResponseArray = new JsonArray($this->connectionModule->_getResponseContent());
         $this->assertFalse(
@@ -1222,7 +1218,6 @@ public function dontSeeResponseContainsJson($json = [])
      * // narrow down matching with JsonPath:
      * // {"users": [{ "name": "davert"}, {"id": 1}]}
      * $I->seeResponseMatchesJsonType(['name' => 'string'], '$.users[0]');
-     * ?>
      * ```
      *
      * You can check if the record contains fields with the data types you expect.
@@ -1244,7 +1239,6 @@ public function dontSeeResponseContainsJson($json = [])
      *      'user_id' => 'integer|string', // multiple types
      *      'company' => ['name' => 'string']
      * ]);
-     * ?>
      * ```
      *
      * You can also apply filters to check values. Filter can be applied with a `:` char after the type declaration,
@@ -1273,25 +1267,22 @@ public function dontSeeResponseContainsJson($json = [])
      * $I->seeResponseMatchesJsonType([
      *      'user_id' => 'string:>0', // works with strings as well
      * ]);
-     * ?>
      * ```
      *
      * You can also add custom filters by using `{@link JsonType::addCustomFilter()}`.
      * See [JsonType reference](http://codeception.com/docs/reference/JsonType).
      *
      * @part json
-     * @param array $jsonType
-     * @param string $jsonPath
      * @see JsonType
      */
-    public function seeResponseMatchesJsonType(array $jsonType, $jsonPath = null)
+    public function seeResponseMatchesJsonType(array $jsonType, string $jsonPath = null): void
     {
         $jsonArray = new JsonArray($this->connectionModule->_getResponseContent());
         if ($jsonPath) {
             $jsonArray = $jsonArray->filterByJsonPath($jsonPath);
         }
 
-        \PHPUnit\Framework\Assert::assertThat($jsonArray, new JsonTypeConstraint($jsonType));
+        Assert::assertThat($jsonArray, new JsonTypeConstraint($jsonType));
     }
 
     /**
@@ -1299,17 +1290,16 @@ public function seeResponseMatchesJsonType(array $jsonType, $jsonPath = null)
      *
      * @part json
      * @param array $jsonType JsonType structure
-     * @param string $jsonPath
      * @see seeResponseMatchesJsonType
      */
-    public function dontSeeResponseMatchesJsonType(array $jsonType, $jsonPath = null)
+    public function dontSeeResponseMatchesJsonType(array $jsonType, string $jsonPath = null): void
     {
         $jsonArray = new JsonArray($this->connectionModule->_getResponseContent());
         if ($jsonPath) {
             $jsonArray = $jsonArray->filterByJsonPath($jsonPath);
         }
 
-        \PHPUnit\Framework\Assert::assertThat($jsonArray, new JsonTypeConstraint($jsonType, false));
+        Assert::assertThat($jsonArray, new JsonTypeConstraint($jsonType, false));
     }
 
     /**
@@ -1317,11 +1307,10 @@ public function dontSeeResponseMatchesJsonType(array $jsonType, $jsonPath = null
      *
      * @part json
      * @part xml
-     * @param $response
      */
-    public function seeResponseEquals($expected)
+    public function seeResponseEquals($expected): void
     {
-        $this->assertEquals($expected, $this->connectionModule->_getResponseContent());
+        $this->assertSame($expected, $this->connectionModule->_getResponseContent());
     }
 
     /**
@@ -1337,9 +1326,8 @@ public function seeResponseEquals($expected)
      *
      * @part json
      * @part xml
-     * @param $code
      */
-    public function seeResponseCodeIs($code)
+    public function seeResponseCodeIs(int $code): void
     {
         $this->connectionModule->seeResponseCodeIs($code);
     }
@@ -1357,9 +1345,8 @@ public function seeResponseCodeIs($code)
      *
      * @part json
      * @part xml
-     * @param $code
      */
-    public function dontSeeResponseCodeIs($code)
+    public function dontSeeResponseCodeIs(int $code): void
     {
         $this->connectionModule->dontSeeResponseCodeIs($code);
     }
@@ -1370,7 +1357,7 @@ public function dontSeeResponseCodeIs($code)
      * @part json
      * @part xml
      */
-    public function seeResponseCodeIsSuccessful()
+    public function seeResponseCodeIsSuccessful(): void
     {
         $this->connectionModule->seeResponseCodeIsSuccessful();
     }
@@ -1381,7 +1368,7 @@ public function seeResponseCodeIsSuccessful()
      * @part json
      * @part xml
      */
-    public function seeResponseCodeIsRedirection()
+    public function seeResponseCodeIsRedirection(): void
     {
         $this->connectionModule->seeResponseCodeIsRedirection();
     }
@@ -1392,7 +1379,7 @@ public function seeResponseCodeIsRedirection()
      * @part json
      * @part xml
      */
-    public function seeResponseCodeIsClientError()
+    public function seeResponseCodeIsClientError(): void
     {
         $this->connectionModule->seeResponseCodeIsClientError();
     }
@@ -1403,7 +1390,7 @@ public function seeResponseCodeIsClientError()
      * @part json
      * @part xml
      */
-    public function seeResponseCodeIsServerError()
+    public function seeResponseCodeIsServerError(): void
     {
         $this->connectionModule->seeResponseCodeIsServerError();
     }
@@ -1415,23 +1402,24 @@ public function seeResponseCodeIsServerError()
      *
      * @part xml
      */
-    public function seeResponseIsXml()
+    public function seeResponseIsXml(): void
     {
         libxml_use_internal_errors(true);
         $doc = simplexml_load_string($this->connectionModule->_getResponseContent());
-        $num = "";
-        $title = "";
+        $num = '';
+        $title = '';
         if ($doc === false) {
             $error = libxml_get_last_error();
             $num = $error->code;
             $title = trim($error->message);
             libxml_clear_errors();
         }
+
         libxml_use_internal_errors(false);
-        \PHPUnit\Framework\Assert::assertNotSame(
+        Assert::assertNotSame(
             false,
             $doc,
-            "xml decoding error #$num with message \"$title\", see http://www.xmlsoft.org/html/libxml-xmlerror.html"
+            sprintf('xml decoding error #%s with message "%s".', $num, $title)
         );
     }
 
@@ -1443,12 +1431,11 @@ public function seeResponseIsXml()
      * $I->seeXmlResponseMatchesXpath('//root/user[@id=1]');
      * ```
      * @part xml
-     * @param $xpath
      */
-    public function seeXmlResponseMatchesXpath($xpath)
+    public function seeXmlResponseMatchesXpath(string $xPath): void
     {
-        $structure = new XmlStructure($this->connectionModule->_getResponseContent());
-        $this->assertTrue($structure->matchesXpath($xpath), 'xpath not matched');
+        $xmlStructure = new XmlStructure($this->connectionModule->_getResponseContent());
+        $this->assertTrue($xmlStructure->matchesXpath($xPath), 'xpath not matched');
     }
 
     /**
@@ -1459,23 +1446,21 @@ public function seeXmlResponseMatchesXpath($xpath)
      * $I->dontSeeXmlResponseMatchesXpath('//root/user[@id=1]');
      * ```
      * @part xml
-     * @param $xpath
      */
-    public function dontSeeXmlResponseMatchesXpath($xpath)
+    public function dontSeeXmlResponseMatchesXpath(string $xPath): void
     {
         $structure = new XmlStructure($this->connectionModule->_getResponseContent());
-        $this->assertFalse($structure->matchesXpath($xpath), 'accidentally matched xpath');
+        $this->assertFalse($structure->matchesXpath($xPath), 'accidentally matched xpath');
     }
 
     /**
      * Finds and returns text contents of element.
      * Element is matched by either CSS or XPath
      *
-     * @param $cssOrXPath
-     * @return string
+     * @param mixed $cssOrXPath
      * @part xml
      */
-    public function grabTextContentFromXmlElement($cssOrXPath)
+    public function grabTextContentFromXmlElement($cssOrXPath): string
     {
         $el = (new XmlStructure($this->connectionModule->_getResponseContent()))->matchElement($cssOrXPath);
         return $el->textContent;
@@ -1485,17 +1470,15 @@ public function grabTextContentFromXmlElement($cssOrXPath)
      * Finds and returns attribute of element.
      * Element is matched by either CSS or XPath
      *
-     * @param $cssOrXPath
-     * @param $attribute
-     * @return string
      * @part xml
      */
-    public function grabAttributeFromXmlElement($cssOrXPath, $attribute)
+    public function grabAttributeFromXmlElement(string $cssOrXPath, string $attribute): string
     {
         $el = (new XmlStructure($this->connectionModule->_getResponseContent()))->matchElement($cssOrXPath);
         if (!$el->hasAttribute($attribute)) {
-            $this->fail("Attribute not found in element matched by '$cssOrXPath'");
+            $this->fail(sprintf("Attribute not found in element matched by '%s'", $cssOrXPath));
         }
+
         return $el->getAttribute($attribute);
     }
 
@@ -1505,12 +1488,12 @@ public function grabAttributeFromXmlElement($cssOrXPath, $attribute)
      *
      * Parameters can be passed either as DOMDocument, DOMNode, XML string, or array (if no attributes).
      *
-     * @param $xml
+     * @param mixed $xml
      * @part xml
      */
-    public function seeXmlResponseEquals($xml)
+    public function seeXmlResponseEquals($xml): void
     {
-        \PHPUnit\Framework\Assert::assertXmlStringEqualsXmlString($this->connectionModule->_getResponseContent(), $xml);
+        Assert::assertXmlStringEqualsXmlString($this->connectionModule->_getResponseContent(), $xml);
     }
 
 
@@ -1520,12 +1503,12 @@ public function seeXmlResponseEquals($xml)
      *
      * Parameter can be passed either as XmlBuilder, DOMDocument, DOMNode, XML string, or array (if no attributes).
      *
-     * @param $xml
+     * @param mixed $xml
      * @part xml
      */
-    public function dontSeeXmlResponseEquals($xml)
+    public function dontSeeXmlResponseEquals($xml): void
     {
-        \PHPUnit\Framework\Assert::assertXmlStringNotEqualsXmlString(
+        Assert::assertXmlStringNotEqualsXmlString(
             $this->connectionModule->_getResponseContent(),
             $xml
         );
@@ -1541,13 +1524,12 @@ public function dontSeeXmlResponseEquals($xml)
      * ``` php
      * <?php
      * $I->seeXmlResponseIncludes("<result>1</result>");
-     * ?>
      * ```
      *
-     * @param $xml
+     * @param mixed $xml
      * @part xml
      */
-    public function seeXmlResponseIncludes($xml)
+    public function seeXmlResponseIncludes($xml): void
     {
         $this->assertStringContainsString(
             XmlUtils::toXml($xml)->C14N(),
@@ -1561,10 +1543,10 @@ public function seeXmlResponseIncludes($xml)
      * Comparison is done by canonicalizing both xml`s.
      * Parameter can be passed either as XmlBuilder, DOMDocument, DOMNode, XML string, or array (if no attributes).
      *
-     * @param $xml
+     * @param mixed $xml
      * @part xml
      */
-    public function dontSeeXmlResponseIncludes($xml)
+    public function dontSeeXmlResponseIncludes($xml): void
     {
         $this->assertStringNotContainsString(
             XmlUtils::toXml($xml)->C14N(),
@@ -1583,7 +1565,6 @@ public function dontSeeXmlResponseIncludes($xml)
      * ```php
      * <?php
      * $I->seeBinaryResponseEquals("8c90748342f19b195b9c6b4eff742ded");
-     * ?>
      * ```
      *
      * Example: Using md5 for a file contents
@@ -1592,7 +1573,6 @@ public function dontSeeXmlResponseIncludes($xml)
      * <?php
      * $fileData = file_get_contents("test_file.jpg");
      * $I->seeBinaryResponseEquals(md5($fileData));
-     * ?>
      * ```
      * Example: Using sha256 hash
      *
@@ -1600,7 +1580,6 @@ public function dontSeeXmlResponseIncludes($xml)
      * <?php
      * $fileData = '/9j/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/yQALCAABAAEBAREA/8wABgAQEAX/2gAIAQEAAD8A0s8g/9k='; // very small jpeg
      * $I->seeBinaryResponseEquals(hash("sha256", base64_decode($fileData)), 'sha256');
-     * ?>
      * ```
      *
      * @param string $hash the hashed data response expected
@@ -1608,10 +1587,10 @@ public function dontSeeXmlResponseIncludes($xml)
      * @part json
      * @part xml
      */
-    public function seeBinaryResponseEquals($hash, $algo = 'md5')
+    public function seeBinaryResponseEquals(string $hash, string $algo = 'sha1'): void
     {
         $responseHash = hash($algo, $this->connectionModule->_getResponseContent());
-        $this->assertEquals($hash, $responseHash);
+        $this->assertSame($hash, $responseHash);
     }
 
     /**
@@ -1620,7 +1599,6 @@ public function seeBinaryResponseEquals($hash, $algo = 'md5')
      * ```php
      * <?php
      * $I->dontSeeBinaryResponseEquals("8c90748342f19b195b9c6b4eff742ded");
-     * ?>
      * ```
      * Opposite to `seeBinaryResponseEquals`
      *
@@ -1629,7 +1607,7 @@ public function seeBinaryResponseEquals($hash, $algo = 'md5')
      * @part json
      * @part xml
      */
-    public function dontSeeBinaryResponseEquals($hash, $algo = 'md5')
+    public function dontSeeBinaryResponseEquals(string $hash, string $algo = 'sha1'): void
     {
         $responseHash = hash($algo, $this->connectionModule->_getResponseContent());
         $this->assertNotEquals($hash, $responseHash);
@@ -1646,7 +1624,7 @@ public function dontSeeBinaryResponseEquals($hash, $algo = 'md5')
      * @part xml
      * @part json
      */
-    public function stopFollowingRedirects()
+    public function stopFollowingRedirects(): void
     {
         $this->client->followRedirects(false);
     }
@@ -1662,7 +1640,7 @@ public function stopFollowingRedirects()
      * @part xml
      * @part json
      */
-    public function startFollowingRedirects()
+    public function startFollowingRedirects(): void
     {
         $this->client->followRedirects(true);
     }
@@ -1675,7 +1653,7 @@ public function startFollowingRedirects()
      * $I->setServerParameters([]);
      * ```
      */
-    public function setServerParameters(array $params)
+    public function setServerParameters(array $params): void
     {
         $this->client->setServerParameters($params);
     }
@@ -1687,7 +1665,7 @@ public function setServerParameters(array $params)
      * $I->haveServerParameter('name', 'value');
      * ```
      */
-    public function haveServerParameter($name, $value)
+    public function haveServerParameter($name, $value): void
     {
         $this->client->setServerParameter($name, $value);
     }
diff --git a/src/Codeception/Util/JsonArray.php b/src/Codeception/Util/JsonArray.php
index 57bc45b..97b783b 100644
--- a/src/Codeception/Util/JsonArray.php
+++ b/src/Codeception/Util/JsonArray.php
@@ -1,21 +1,22 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Codeception\Util;
 
+use DOMDocument;
+use DOMNode;
+use DOMNodeList;
+use DOMXPath;
+use Exception;
 use Flow\JSONPath\JSONPath;
 use InvalidArgumentException;
-use DOMDocument;
 
 class JsonArray
 {
-    /**
-     * @var array
-     */
-    protected $jsonArray = [];
-    
-    /**
-     * @var DOMDocument
-     */
-    protected $jsonXml = null;
+    protected array $jsonArray = [];
+
+    protected ?DOMDocument $jsonXml = null;
 
     public function __construct($jsonString)
     {
@@ -43,7 +44,7 @@ public function __construct($jsonString)
         }
     }
 
-    public function toXml()
+    public function toXml(): DOMDocument
     {
         if ($this->jsonXml) {
             return $this->jsonXml;
@@ -68,39 +69,43 @@ public function toXml()
         return $dom;
     }
 
-    /**
-     * @return array
-     */
-    public function toArray()
+    public function toArray(): array
     {
         return $this->jsonArray;
     }
 
-    public function filterByXPath($xpath)
+    /**
+     * @return DOMNodeList|bool
+     */
+    public function filterByXPath(string $xPath)
     {
-        $path = new \DOMXPath($this->toXml());
-        return $path->query($xpath);
+        $path = new DOMXPath($this->toXml());
+        return $path->query($xPath);
     }
 
-    public function filterByJsonPath($jsonPath)
+    public function filterByJsonPath(string $jsonPath): array
     {
-        if (!class_exists('Flow\JSONPath\JSONPath')) {
-            throw new \Exception('JSONPath library not installed. Please add `softcreatr/jsonpath` to composer.json');
+        if (!class_exists(JSONPath::class)) {
+            throw new Exception('JSONPath library not installed. Please add `softcreatr/jsonpath` to composer.json');
         }
+
         return (new JSONPath($this->jsonArray))->find($jsonPath)->getData();
     }
 
+    /**
+     * @return string|false
+     */
     public function getXmlString()
     {
         return $this->toXml()->saveXML();
     }
 
-    public function containsArray(array $needle)
+    public function containsArray(array $needle): bool
     {
         return (new ArrayContainsComparator($this->jsonArray))->containsArray($needle);
     }
 
-    private function arrayToXml(\DOMDocument $doc, \DOMNode $node, $array)
+    private function arrayToXml(DOMDocument $doc, DOMNode $node, array $array): void
     {
         foreach ($array as $key => $value) {
             if (is_numeric($key)) {
@@ -109,12 +114,14 @@ private function arrayToXml(\DOMDocument $doc, \DOMNode $node, $array)
             } else {
                 try {
                     $subNode = $doc->createElement($key);
-                } catch (\Exception $e) {
+                } catch (Exception $exception) {
                     $key = $this->getValidTagNameForInvalidKey($key);
                     $subNode = $doc->createElement($key);
                 }
+
                 $node->appendChild($subNode);
             }
+
             if (is_array($value)) {
                 $this->arrayToXml($doc, $subNode, $value);
             } else {
@@ -131,6 +138,7 @@ private function getValidTagNameForInvalidKey($key)
             $map[$key] = $tagName;
             codecept_debug($tagName . ' is "' . $key . '"');
         }
+
         return $map[$key];
     }
 }
diff --git a/src/Codeception/Util/JsonType.php b/src/Codeception/Util/JsonType.php
index ee4a559..ced4134 100644
--- a/src/Codeception/Util/JsonType.php
+++ b/src/Codeception/Util/JsonType.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Codeception\Util;
 
 /**
@@ -21,7 +23,6 @@
  * $jsonType->matches([
  *   'id' => 'string',
  * ]); // => `id: 1` is not of type string
- * ?>
  * ```
  *
  * Class JsonType
@@ -29,22 +30,26 @@
  */
 class JsonType
 {
+    /**
+     * @var array|JsonArray
+     */
     protected $jsonArray;
 
-    protected static $customFilters = [];
+    protected static array $customFilters = [];
 
     /**
      * Creates instance of JsonType
      * Pass an array or `\Codeception\Util\JsonArray` with data.
      * If non-associative array is passed - the very first element of it will be used for matching.
      *
-     * @param $jsonArray array|\Codeception\Util\JsonArray
+     * @param $jsonArray array|JsonArray
      */
     public function __construct($jsonArray)
     {
         if ($jsonArray instanceof JsonArray) {
             $jsonArray = $jsonArray->toArray();
         }
+
         $this->jsonArray = $jsonArray;
     }
 
@@ -67,13 +72,9 @@ public function __construct($jsonArray)
      *   return strlen($value) == $len;
      * });
      * // use it as 'string:len(5)'
-     * ?>
      * ```
-     *
-     * @param          $name
-     * @param callable $callable
      */
-    public static function addCustomFilter($name, callable $callable)
+    public static function addCustomFilter(string $name, callable $callable): void
     {
         static::$customFilters[$name] = $callable;
     }
@@ -81,7 +82,7 @@ public static function addCustomFilter($name, callable $callable)
     /**
      * Removes all custom filters
      */
-    public static function cleanCustomFilters()
+    public static function cleanCustomFilters(): void
     {
         static::$customFilters = [];
     }
@@ -91,33 +92,38 @@ public static function cleanCustomFilters()
      * If matching fails function returns a string with a message describing failure.
      * On success returns `true`.
      *
-     * @param array $jsonType
-     * @return bool|string
+     * @return string|bool
      */
     public function matches(array $jsonType)
     {
         if (array_key_exists(0, $this->jsonArray) && is_array($this->jsonArray[0])) {
             // a list of items
             $msg = '';
-            foreach ($this->jsonArray as $array) {
-                $res = $this->typeComparison($array, $jsonType);
+            foreach ($this->jsonArray as $singleJsonArray) {
+                $res = $this->typeComparison($singleJsonArray, $jsonType);
                 if ($res !== true) {
                     $msg .= "\n" . $res;
                 }
             }
-            if ($msg) {
+
+            if ($msg !== '') {
                 return $msg;
             }
+
             return true;
         }
+
         return $this->typeComparison($this->jsonArray, $jsonType);
     }
 
-    protected function typeComparison($data, $jsonType)
+    /**
+     * @return string|bool
+     */
+    protected function typeComparison(array $data, array $jsonType)
     {
         foreach ($jsonType as $key => $type) {
             if (!array_key_exists($key, $data)) {
-                return "Key `$key` doesn't exist in " . json_encode($data);
+                return sprintf("Key `%s` doesn't exist in ", $key) . json_encode($data, JSON_THROW_ON_ERROR);
             }
 
             if (is_array($jsonType[$key])) {
@@ -138,7 +144,7 @@ protected function typeComparison($data, $jsonType)
             preg_match_all($regexMatcher, $type, $regexes);
 
             // Do the same match as above, but replace the the 'any character' + delimiter with a place holder ($${count}).
-            $filterType = preg_replace_callback($regexMatcher, function () {
+            $filterType = preg_replace_callback($regexMatcher, function (): string {
                 static $count = 0;
                 return ':regex($$' . $count++ . ')';
             }, $type);
@@ -163,13 +169,13 @@ protected function typeComparison($data, $jsonType)
 
                 foreach ($filters as $filter) {
                     // Fill regex pattern back into the filter.
-                    $filter = preg_replace_callback('/\$\$\d+/', function ($m) use ($regexes) {
+                    $filter = preg_replace_callback('#\$\$\d+#', function ($m) use ($regexes) {
                         $pos = (int)substr($m[0], 2);
 
                         return $regexes[1][$pos];
                     }, $filter);
 
-                    $matched = $matched && $this->matchFilter($filter, $data[$key]);
+                    $matched = $matched && $this->matchFilter($filter, (string) $data[$key]);
                 }
 
                 if ($matched) {
@@ -181,10 +187,11 @@ protected function typeComparison($data, $jsonType)
                 return sprintf("`$key: %s` is of type `$type`", var_export($data[$key], true));
             }
         }
+
         return true;
     }
 
-    protected function matchFilter($filter, $value)
+    protected function matchFilter(string $filter, string $value)
     {
         $filter = trim($filter);
         if (strpos($filter, '!') === 0) {
@@ -193,51 +200,59 @@ protected function matchFilter($filter, $value)
 
         // apply custom filters
         foreach (static::$customFilters as $customFilter => $callable) {
-            if (strpos($customFilter, '/') === 0) {
-                if (preg_match($customFilter, $filter, $matches)) {
-                    array_shift($matches);
-                    return call_user_func_array($callable, array_merge([$value], $matches));
-                }
+            if (strpos($customFilter, '/') === 0 && preg_match($customFilter, $filter, $matches)) {
+                array_shift($matches);
+                return call_user_func_array($callable, array_merge([$value], $matches));
             }
+
             if ($customFilter == $filter) {
                 return $callable($value);
             }
         }
 
         if (strpos($filter, '=') === 0) {
-            return $value == substr($filter, 1);
+            return $value === substr($filter, 1);
         }
+
         if ($filter === 'url') {
             return filter_var($value, FILTER_VALIDATE_URL);
         }
+
         if ($filter === 'date') {
             return preg_match(
-                '/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(\.\d+)?(?:Z|(\+|-)([\d|:]*))?$/',
+                '#^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(\.\d+)?(?:Z|(\+|-)([\d|:]*))?$#',
                 $value
             );
         }
+
         if ($filter === 'email') { // from http://emailregex.com/
             // @codingStandardsIgnoreStart
-            return preg_match('/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}@)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/iD',
+            return preg_match('#^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}@)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4]\d)|(?:1\d{2})|(?:[1-9]?\d))(?:\.(?:(?:25[0-5])|(?:2[0-4]\d)|(?:1\d{2})|(?:[1-9]?\d))){3}))\]))$#iD',
                 $value);
             // @codingStandardsIgnoreEnd
         }
+
         if ($filter === 'empty') {
             return empty($value);
         }
-        if (preg_match('~^regex\((.*?)\)$~', $filter, $matches)) {
+
+        if (preg_match('#^regex\((.*?)\)$#', $filter, $matches)) {
             return preg_match($matches[1], $value);
         }
-        if (preg_match('~^>=(-?[\d\.]+)$~', $filter, $matches)) {
+
+        if (preg_match('#^>=(-?[\d\.]+)$#', $filter, $matches)) {
             return (float)$value >= (float)$matches[1];
         }
-        if (preg_match('~^<=(-?[\d\.]+)$~', $filter, $matches)) {
+
+        if (preg_match('#^<=(-?[\d\.]+)$#', $filter, $matches)) {
             return (float)$value <= (float)$matches[1];
         }
-        if (preg_match('~^>(-?[\d\.]+)$~', $filter, $matches)) {
+
+        if (preg_match('#^>(-?[\d\.]+)$#', $filter, $matches)) {
             return (float)$value > (float)$matches[1];
         }
-        if (preg_match('~^<(-?[\d\.]+)$~', $filter, $matches)) {
+
+        if (preg_match('#^<(-?[\d\.]+)$#', $filter, $matches)) {
             return (float)$value < (float)$matches[1];
         }
 
diff --git a/tests/data/rest/index.php b/tests/data/rest/index.php
index c04ebaa..62e950a 100755
--- a/tests/data/rest/index.php
+++ b/tests/data/rest/index.php
@@ -1,38 +1,35 @@
 <?php
 
-include_once 'server.php';
+include_once __DIR__ . '/server.php';
 
 $GLOBALS['RESTmap'] = [];
 
 $GLOBALS['RESTmap']['GET'] = [
-    'user' => function() {
-        return [
-            'name'    => 'davert',
-            'email'   => 'davert@mail.ua',
-            'aliases' => [
-                'DavertMik',
-                'davert.ua'
-            ],
-            'address' => [
-                'city'    => 'Kyiv',
-                'country' => 'Ukraine',
-            ]];
-    },
-    'zeroes' => function() {
-        return [
-            'responseCode' => 0,
-            'message' => 'OK',
-            'data' => [
-                9,
-                0,
-                0
-            ],
-        ];
-    },
+    'user' => fn(): array => [
+        'name'    => 'davert',
+        'email'   => 'davert@mail.ua',
+        'aliases' => [
+            'DavertMik',
+            'davert.ua'
+        ],
+        'address' => [
+            'city'    => 'Kyiv',
+            'country' => 'Ukraine',
+        ]],
+    'zeroes' => fn(): array => [
+        'responseCode' => 0,
+        'message' => 'OK',
+        'data' => [
+            9,
+            0,
+            0
+        ],
+    ],
     'foo' => function() {
         if (isset($_SERVER['HTTP_FOO'])) {
             return 'foo: "' . $_SERVER['HTTP_FOO'] . '"';
         }
+
         return 'foo: not found';
     }
 
@@ -43,11 +40,9 @@
         $name = $_POST['name'];
         return ['name' => $name];
     },
-    'file-upload' => function() {
-        return [
-            'uploaded' => isset($_FILES['file']['tmp_name']) && file_exists($_FILES['file']['tmp_name']),
-        ];
-    }
+    'file-upload' => fn(): array => [
+        'uploaded' => isset($_FILES['file']['tmp_name']) && file_exists($_FILES['file']['tmp_name']),
+    ]
 ];
 
 $GLOBALS['RESTmap']['PUT'] = [
@@ -60,7 +55,7 @@
 ];
 
 $GLOBALS['RESTmap']['DELETE'] = [
-    'user' => function() {
+    'user' => function(): void {
         header('error', false, 404);
     }
 ];
diff --git a/tests/data/rest/server.php b/tests/data/rest/server.php
index 9c862f1..8fcd26b 100755
--- a/tests/data/rest/server.php
+++ b/tests/data/rest/server.php
@@ -1,23 +1,21 @@
 <?php
-function RESTServer()
+
+function RESTServer(): void
 {
     // find the function/method to call
     $callback = NULL;
-    if (preg_match('/rest\/([^\/]+)/i', $_SERVER['REQUEST_URI'], $m)) {
-        if (isset($GLOBALS['RESTmap'][$_SERVER['REQUEST_METHOD']][$m[1]])) {
-            $callback = $GLOBALS['RESTmap'][$_SERVER['REQUEST_METHOD']][$m[1]];
-        }
+    if (preg_match('#rest\/([^\/]+)#i', $_SERVER['REQUEST_URI'], $m) && isset($GLOBALS['RESTmap'][$_SERVER['REQUEST_METHOD']][$m[1]])) {
+        $callback = $GLOBALS['RESTmap'][$_SERVER['REQUEST_METHOD']][$m[1]];
     }
 
-
     if ($callback) {
 
         // get the request data
         $data = NULL;
         if ($_SERVER['REQUEST_METHOD'] === 'GET') {
             $data = $_GET;
-        } else if ($tmp = file_get_contents('php://input')) {
-            $data = json_decode($tmp);
+        } elseif ($tmp = file_get_contents('php://input')) {
+            $data = json_decode($tmp, null, 512, JSON_THROW_ON_ERROR);
         }
 
         $response = call_user_func($callback, $data);
@@ -25,6 +23,7 @@ function RESTServer()
             print $response;
             return;
         }
-        print json_encode($response);
+
+        print json_encode($response, JSON_THROW_ON_ERROR);
     }
 }
diff --git a/tests/unit/Codeception/Module/RestTest.php b/tests/unit/Codeception/Module/RestTest.php
index 818d9b2..20ded87 100644
--- a/tests/unit/Codeception/Module/RestTest.php
+++ b/tests/unit/Codeception/Module/RestTest.php
@@ -1,33 +1,39 @@
 <?php
 
+declare(strict_types=1);
+
 use Codeception\Configuration;
-use Codeception\Example;
+use Codeception\Module\REST;
 use Codeception\Module\UniversalFramework;
+use Codeception\Stub;
 use Codeception\Test\Unit;
-use Codeception\Util\Stub;
+use Codeception\Util\Maybe;
+use PHPUnit\Framework\AssertionFailedError;
+use PHPUnit\Framework\ExpectationFailedException;
+use Symfony\Component\BrowserKit\Request as SymfonyRequest;
+use Symfony\Component\BrowserKit\Response as SymfonyResponse;
 
 /**
  * Class RestTest
  * @group appveyor
  */
-class RestTest extends Unit
+final class RestTest extends Unit
 {
-    /**
-     * @var \Codeception\Module\REST
-     */
-    protected $module;
+    protected REST $module;
 
-    public function _setUp()
+    protected function _setUp()
     {
         $index = Configuration::dataDir() . '/rest/index.php';
 
-        $container = Stub::make('Codeception\Lib\ModuleContainer');
+        $container = Stub::make(\Codeception\Lib\ModuleContainer::class);
         $connectionModule = new UniversalFramework($container, ['index' => $index]);
         $connectionModule->_initialize();
-        $this->module = Stub::make('\Codeception\Module\REST');
+
+        $this->module = Stub::make(\Codeception\Module\REST::class);
         $this->module->_inject($connectionModule);
         $this->module->_initialize();
-        $this->module->_before(Stub::makeEmpty('\Codeception\Test\Test'));
+        $this->module->_before(Stub::makeEmpty(\Codeception\Test\Test::class));
+
         $this->module->client->setServerParameters([
             'SCRIPT_FILENAME' => 'index.php',
             'SCRIPT_NAME' => 'index',
@@ -38,26 +44,28 @@ public function _setUp()
 
     public function testConflictsWithAPI()
     {
-        $this->assertInstanceOf('Codeception\Lib\Interfaces\ConflictsWithModule', $this->module);
-        $this->assertEquals('Codeception\Lib\Interfaces\API', $this->module->_conflicts());
+        $this->assertInstanceOf(\Codeception\Lib\Interfaces\ConflictsWithModule::class, $this->module);
+        $this->assertSame(\Codeception\Lib\Interfaces\API::class, $this->module->_conflicts());
     }
 
     private function setStubResponse($response)
     {
-        $connectionModule = Stub::make('\Codeception\Module\UniversalFramework', ['_getResponseContent' => $response]);
+        $connectionModule = Stub::make(\Codeception\Module\UniversalFramework::class, ['_getResponseContent' => $response]);
         $this->module->_inject($connectionModule);
         $this->module->_initialize();
-        $this->module->_before(Stub::makeEmpty('\Codeception\Test\Test'));
+        $this->module->_before(Stub::makeEmpty(\Codeception\Test\Test::class));
     }
 
     public function testBeforeHookResetsVariables()
     {
         $this->module->haveHttpHeader('Origin', 'http://www.example.com');
         $this->module->sendGET('/rest/user/');
+
         $server = $this->module->client->getInternalRequest()->getServer();
         $this->assertArrayHasKey('HTTP_ORIGIN', $server);
-        $this->module->_before(Stub::makeEmpty('\Codeception\Test\Test'));
+        $this->module->_before(Stub::makeEmpty(\Codeception\Test\Test::class));
         $this->module->sendGET('/rest/user/');
+
         $server = $this->module->client->getInternalRequest()->getServer();
         $this->assertArrayNotHasKey('HTTP_ORIGIN', $server);
     }
@@ -107,13 +115,13 @@ public function testGrabDataFromResponseByJsonPath()
     {
         $this->module->sendGET('/rest/user/');
         // simple assoc array
-        $this->assertEquals(['davert@mail.ua'], $this->module->grabDataFromResponseByJsonPath('$.email'));
+        $this->assertSame(['davert@mail.ua'], $this->module->grabDataFromResponseByJsonPath('$.email'));
         // nested assoc array
-        $this->assertEquals(['Kyiv'], $this->module->grabDataFromResponseByJsonPath('$.address.city'));
+        $this->assertSame(['Kyiv'], $this->module->grabDataFromResponseByJsonPath('$.address.city'));
         // nested index array
-        $this->assertEquals(['DavertMik'], $this->module->grabDataFromResponseByJsonPath('$.aliases[0]'));
+        $this->assertSame(['DavertMik'], $this->module->grabDataFromResponseByJsonPath('$.aliases[0]'));
         // empty if data not found
-        $this->assertEquals([], $this->module->grabDataFromResponseByJsonPath('$.address.street'));
+        $this->assertSame([], $this->module->grabDataFromResponseByJsonPath('$.address.street'));
     }
 
     public function testValidJson()
@@ -127,10 +135,11 @@ public function testValidJson()
 
     public function testInvalidJson()
     {
-        $this->expectException('PHPUnit\Framework\ExpectationFailedException');
+        $this->expectException(ExpectationFailedException::class);
         $this->setStubResponse('{xxx = yyy}');
         $this->module->seeResponseIsJson();
     }
+
     public function testValidXml()
     {
         $this->setStubResponse('<xml></xml>');
@@ -149,7 +158,7 @@ public function testXmlResponseEquals()
 
     public function testInvalidXml()
     {
-        $this->expectException('PHPUnit\Framework\ExpectationFailedException');
+        $this->expectException(ExpectationFailedException::class);
         $this->setStubResponse('<xml><name>John</surname></xml>');
         $this->module->seeResponseIsXml();
     }
@@ -203,11 +212,11 @@ public function testApplicationJsonIncludesJsonAsContent()
     {
         $this->module->haveHttpHeader('Content-Type', 'application/json');
         $this->module->sendPOST('/', ['name' => 'john']);
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertContains('application/json', $request->getServer());
         $server = $request->getServer();
-        $this->assertEquals('application/json', $server['HTTP_CONTENT_TYPE']);
+        $this->assertSame('application/json', $server['HTTP_CONTENT_TYPE']);
         $this->assertJson($request->getContent());
         $this->assertEmpty($request->getParameters());
     }
@@ -216,40 +225,39 @@ public function testApplicationJsonIncludesObjectSerialized()
     {
         $this->module->haveHttpHeader('Content-Type', 'application/json');
         $this->module->sendPOST('/', new JsonSerializedItem());
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertContains('application/json', $request->getServer());
         $this->assertJson($request->getContent());
     }
 
     /**
-     * @param string $method
-     *
      * @dataProvider requestBodyAwareMethods
      */
-    public function testRequestBodyIsSentAsJsonForThisMethod($method)
+    public function testRequestBodyIsSentAsJsonForThisMethod(string $method)
     {
         $this->module->haveHttpHeader('Content-Type', 'application/json');
         $this->module->send($method, '/', ['name' => 'john']);
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
-        $this->assertSame(json_encode(['name' => 'john']), $request->getContent());
+        $this->assertSame(json_encode(['name' => 'john'], JSON_THROW_ON_ERROR), $request->getContent());
     }
 
     /**
-     * @param string $method
-     *
      * @dataProvider requestBodyAwareMethods
      */
-    public function testRequestBodyIsSentUrlEncodedForThisMethod($method)
+    public function testRequestBodyIsSentUrlEncodedForThisMethod(string $method)
     {
         $this->module->send($method, '/', ['name' => 'john']);
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertSame(http_build_query(['name' => 'john']), $request->getContent());
     }
 
-    public function requestBodyAwareMethods()
+    /**
+     * @return array<string, array<string>>
+     */
+    public function requestBodyAwareMethods(): array
     {
         return [
             'POST'   => ['POST'],
@@ -260,15 +268,13 @@ public function requestBodyAwareMethods()
     }
 
     /**
-     * @param string $method
-     *
      * @dataProvider queryParamsAwareMethods
      */
-    public function testJsonRequestBodyIsNotSentForThisMethod($method)
+    public function testJsonRequestBodyIsNotSentForThisMethod(string $method)
     {
         $this->module->haveHttpHeader('Content-Type', 'application/json');
         $this->module->send($method, '/', ['name' => 'john']);
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertNull($request->getContent());
         $this->assertContains('john', $request->getParameters());
@@ -276,20 +282,18 @@ public function testJsonRequestBodyIsNotSentForThisMethod($method)
 
 
     /**
-     * @param string $method
-     *
      * @dataProvider queryParamsAwareMethods
      */
-    public function testUrlEncodedRequestBodyIsNotSentForThisMethod($method)
+    public function testUrlEncodedRequestBodyIsNotSentForThisMethod(string $method)
     {
         $this->module->send($method, '/', ['name' => 'john']);
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertNull($request->getContent());
         $this->assertContains('john', $request->getParameters());
     }
 
-    public function queryParamsAwareMethods()
+    public function queryParamsAwareMethods(): array
     {
         return [
             'GET'     => ['GET'],
@@ -301,13 +305,14 @@ public function queryParamsAwareMethods()
     /**
      * @dataProvider queryParamsAwareMethods
      */
-    public function testThrowsExceptionIfParametersIsString($method)
+    public function testThrowsExceptionIfParametersIsString(string $method)
     {
         $this->expectExceptionMessage($method . ' parameters must be passed in array format');
         $this->module->send($method, '/', 'string');
     }
 
     /**
+     * @param array|object $parameters
      * @dataProvider invalidParameterTypes
      */
     public function testThrowsExceptionIfParametersIsOfUnexpectedType($parameters)
@@ -316,7 +321,7 @@ public function testThrowsExceptionIfParametersIsOfUnexpectedType($parameters)
         $this->module->sendPOST('/', $parameters);
     }
 
-    public function invalidParameterTypes()
+    public function invalidParameterTypes(): array
     {
         return [
             'boolean'  => [true],
@@ -329,20 +334,20 @@ public function invalidParameterTypes()
 
     public function testThrowsExceptionIfUrlIsNotString()
     {
-        $this->expectExceptionMessage('URL must be string');
+        $this->expectException(TypeError::class);
         $this->module->sendPOST([1]);
     }
 
     public function testThrowsExceptionIfParametersIsJsonSerializableButContentTypeIsNotSet()
     {
         $this->expectExceptionMessage("parameters is JsonSerializable object, but Content-Type header is not set to application/json");
-        $parameters = new \Codeception\Util\Maybe(['foo']);
+        $parameters = new Maybe(['foo']);
         $this->module->sendPOST('/', $parameters);
     }
 
     public function testDoesntThrowExceptionIfParametersIsJsonSerializableAndContentTypeIsSet()
     {
-        $parameters = new \Codeception\Util\Maybe(['foo']);
+        $parameters = new Maybe(['foo']);
 
         $this->module->haveHttpHeader('Content-Type', 'application/json');
         $this->module->sendPOST('/', $parameters);
@@ -352,14 +357,14 @@ public function testDoesntThrowExceptionIfParametersIsJsonSerializableAndContent
     public function testUrlIsFull()
     {
         $this->module->sendGET('/api/v1/users');
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
-        $this->assertEquals('http://localhost/api/v1/users', $request->getUri());
+        $this->assertSame('http://localhost/api/v1/users', $request->getUri());
     }
 
     public function testSeeHeaders()
     {
-        $response = new \Symfony\Component\BrowserKit\Response("", 200, [
+        $response = new SymfonyResponse("", 200, [
             'Cache-Control' => ['no-cache', 'no-store'],
             'Content_Language' => 'en-US'
         ]);
@@ -371,15 +376,15 @@ public function testSeeHeaders()
         $this->module->dontSeeHttpHeader('Content-Language', 'en-RU');
         $this->module->dontSeeHttpHeader('Content-Language1');
         $this->module->seeHttpHeaderOnce('Content-Language');
-        $this->assertEquals('en-US', $this->module->grabHttpHeader('Content-Language'));
-        $this->assertEquals('no-cache', $this->module->grabHttpHeader('Cache-Control'));
-        $this->assertEquals(['no-cache', 'no-store'], $this->module->grabHttpHeader('Cache-Control', false));
+        $this->assertSame('en-US', $this->module->grabHttpHeader('Content-Language'));
+        $this->assertSame('no-cache', $this->module->grabHttpHeader('Cache-Control'));
+        $this->assertSame(['no-cache', 'no-store'], $this->module->grabHttpHeader('Cache-Control', false));
     }
 
     public function testSeeHeadersOnce()
     {
         $this->shouldFail();
-        $response = new \Symfony\Component\BrowserKit\Response("", 200, [
+        $response = new SymfonyResponse("", 200, [
             'Cache-Control' => ['no-cache', 'no-store'],
         ]);
         $this->module->client->mockResponse($response);
@@ -481,7 +486,7 @@ public function testApplicationJsonSubtypeIncludesObjectSerialized()
     {
         $this->module->haveHttpHeader('Content-Type', 'application/resource+json');
         $this->module->sendPOST('/', new JsonSerializedItem());
-        /** @var $request \Symfony\Component\BrowserKit\Request  **/
+        /** @var SymfonyRequest $request **/
         $request = $this->module->client->getRequest();
         $this->assertContains('application/resource+json', $request->getServer());
         $this->assertJson($request->getContent());
@@ -508,8 +513,8 @@ public function testMatchJsonTypeFailsWithNiceMessage()
         try {
             $this->module->seeResponseMatchesJsonType(['zzz' => 'string']);
             $this->fail('it had to throw exception');
-        } catch (PHPUnit\Framework\AssertionFailedError $e) {
-            $this->assertEquals('Key `zzz` doesn\'t exist in {"xxx":"yyy","user_id":1}', $e->getMessage());
+        } catch (AssertionFailedError $assertionFailedError) {
+            $this->assertSame('Key `zzz` doesn\'t exist in {"xxx":"yyy","user_id":1}', $assertionFailedError->getMessage());
         }
     }
 
@@ -519,8 +524,8 @@ public function testDontMatchJsonTypeFailsWithNiceMessage()
         try {
             $this->module->dontSeeResponseMatchesJsonType(['xxx' => 'string']);
             $this->fail('it had to throw exception');
-        } catch (PHPUnit\Framework\AssertionFailedError $e) {
-            $this->assertEquals('Unexpectedly response matched: {"xxx":"yyy","user_id":1}', $e->getMessage());
+        } catch (AssertionFailedError $e) {
+            $this->assertSame('Unexpectedly response matched: {"xxx":"yyy","user_id":1}', $e->getMessage());
         }
     }
 
@@ -560,7 +565,7 @@ public function testSeeBinaryResponseEquals()
     {
         $data = base64_decode('/9j/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/yQALCAABAAEBAREA/8wABgAQEAX/2gAIAQEAAD8A0s8g/9k=');
         $this->setStubResponse($data);
-        $this->module->seeBinaryResponseEquals(md5($data));
+        $this->module->seeBinaryResponseEquals(sha1($data));
     }
 
     public function testDontSeeBinaryResponseEquals()
@@ -572,7 +577,7 @@ public function testDontSeeBinaryResponseEquals()
 
     public function testAmDigestAuthenticatedThrowsExceptionWithFunctionalModules()
     {
-        $this->expectException('\Codeception\Exception\ModuleException');
+        $this->expectException(\Codeception\Exception\ModuleException::class);
         $this->expectExceptionMessage('Not supported by functional modules');
         $this->module->amDigestAuthenticated('username', 'password');
     }
@@ -581,11 +586,13 @@ public function testCanResetHTTPAuthenticated()
     {
         $this->module->amHttpAuthenticated('user', 'pass');
         $this->module->sendGET('/rest/user/');
+
         $server = $this->module->client->getRequest()->getServer();
         $this->assertArrayHasKey('PHP_AUTH_USER', $server);
         $this->assertArrayHasKey('PHP_AUTH_PW', $server);
         $this->module->setServerParameters([]);
         $this->module->sendGET('/rest/user/');
+
         $server = $this->module->client->getRequest()->getServer();
         $this->assertArrayNotHasKey('PHP_AUTH_USER', $server);
         $this->assertArrayNotHasKey('PHP_AUTH_PW', $server);
@@ -595,6 +602,7 @@ public function testHaveServerParameter()
     {
         $this->module->haveServerParameter('my', 'param');
         $this->module->sendGET('/rest/user/');
+
         $server = $this->module->client->getRequest()->getServer();
         $this->assertArrayHasKey('my', $server);
     }
@@ -608,8 +616,8 @@ public function testHaveServerParameter()
      * @dataProvider schemaAndResponse
      */
 
-    public function testSeeResponseIsValidOnJsonSchemachesJsonSchema($schema, $response, $outcome, $error) {
-
+    public function testSeeResponseIsValidOnJsonSchemachesJsonSchema(string $schema, string $response, bool $outcome, string $error)
+    {
         $response = file_get_contents(codecept_data_dir($response));
         $this->setStubResponse($response);
 
@@ -617,6 +625,7 @@ public function testSeeResponseIsValidOnJsonSchemachesJsonSchema($schema, $respo
             $this->expectExceptionMessage($error);
             $this->shouldFail();
         }
+
         $this->module->seeResponseIsValidOnJsonSchema(codecept_data_dir($schema));
     }
 
@@ -632,17 +641,13 @@ public function testSeeResponseIsValidOnJsonSchemachesJsonSchemaString() {
                 ]
             ]
         ];
-        $this->module->seeResponseIsValidOnJsonSchemaString(json_encode($schema));
+        $this->module->seeResponseIsValidOnJsonSchemaString(json_encode($schema, JSON_THROW_ON_ERROR));
     }
 
     /**
-     * @param $configUrl
-     * @param $requestUrl
-     * @param $expectedFullUrl
-     *
      * @dataProvider configAndRequestUrls
      */
-    public function testRestExecute($configUrl, $requestUrl, $expectedFullUrl)
+    public function testRestExecute(string $configUrl, string $requestUrl, string $expectedFullUrl)
     {
         $connectionModule = $this->createMock(
             UniversalFramework::class
@@ -658,23 +663,23 @@ public function testRestExecute($configUrl, $requestUrl, $expectedFullUrl)
                     $server,
                     $content
                 ) use ($expectedFullUrl) {
-                    \PHPUnit\Framework\Assert::assertEquals($expectedFullUrl, $uri);
+                    \PHPUnit\Framework\Assert::assertSame($expectedFullUrl, $uri);
                 })
             );
 
         $config = ['url' => $configUrl];
 
         /** @var REST */
-        $module = Stub::make('\Codeception\Module\REST');
+        $module = Stub::make(\Codeception\Module\REST::class);
         $module->_setConfig($config);
         $module->_inject($connectionModule);
         $module->_initialize();
-        $module->_before(Stub::makeEmpty('\Codeception\Test\Test'));
+        $module->_before(Stub::makeEmpty(\Codeception\Test\Test::class));
 
         $module->sendGET($requestUrl);
     }
 
-    public static function schemaAndResponse()
+    public static function schemaAndResponse(): array
     {
         return [
             //schema, responsefile, valid
@@ -685,7 +690,7 @@ public static function schemaAndResponse()
         ];
     }
 
-    public static function configAndRequestUrls()
+    public static function configAndRequestUrls(): array
     {
         return [
                 //$configUrl, $requestUrl, $expectedFullUrl
@@ -705,15 +710,14 @@ public static function configAndRequestUrls()
 
     protected function shouldFail()
     {
-        $this->expectException('PHPUnit\Framework\AssertionFailedError');
+        $this->expectException(AssertionFailedError::class);
     }
 }
 
 class JsonSerializedItem implements JsonSerializable
 {
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return array("hello" => "world");
     }
 }
-
diff --git a/tests/unit/Codeception/Util/JsonArrayTest.php b/tests/unit/Codeception/Util/JsonArrayTest.php
index 483189d..8f5daaa 100644
--- a/tests/unit/Codeception/Util/JsonArrayTest.php
+++ b/tests/unit/Codeception/Util/JsonArrayTest.php
@@ -1,13 +1,15 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Codeception\Util;
 
-class JsonArrayTest extends \Codeception\Test\Unit
-{
+use Codeception\Test\Unit;
+use InvalidArgumentException;
 
-    /**
-     * @var JsonArray
-     */
-    protected $jsonArray;
+final class JsonArrayTest extends Unit
+{
+    protected ?JsonArray $jsonArray = null;
 
     protected function _before()
     {
@@ -31,7 +33,7 @@ public function testXmlArrayConversion2()
             . '{"user":"John Doe","age":27,"tags":["web-dev","java"]}]'
         );
         $this->assertStringContainsString('<tags>wed-dev</tags>', $jsonArray->toXml()->saveXML());
-        $this->assertEquals(2, $jsonArray->filterByXPath('//user')->length);
+        $this->assertSame(2, $jsonArray->filterByXPath('//user')->length);
     }
 
     public function testXPathLocation()
@@ -46,7 +48,7 @@ public function testJsonPathLocation()
         $this->assertNotEmpty($this->jsonArray->filterByJsonPath('$..user'));
         $this->assertNotEmpty($this->jsonArray->filterByJsonPath('$.ticket.user.name'));
         $this->assertNotEmpty($this->jsonArray->filterByJsonPath('$..user.name'));
-        $this->assertEquals(['Davert'], $this->jsonArray->filterByJsonPath('$.ticket.user.name'));
+        $this->assertSame(['Davert'], $this->jsonArray->filterByJsonPath('$.ticket.user.name'));
         $this->assertEmpty($this->jsonArray->filterByJsonPath('$..invalid'));
     }
 
@@ -55,7 +57,7 @@ public function testJsonPathLocation()
      */
     public function testThrowsInvalidArgumentExceptionIfJsonIsInvalid()
     {
-        $this->expectException('InvalidArgumentException');
+        $this->expectException(InvalidArgumentException::class);
         new JsonArray('{"test":');
     }
 
@@ -65,7 +67,7 @@ public function testThrowsInvalidArgumentExceptionIfJsonIsInvalid()
     public function testConvertsBareJson()
     {
         $jsonArray = new JsonArray('"I am a {string}."');
-        $this->assertEquals(['I am a {string}.'], $jsonArray->toArray());
+        $this->assertSame(['I am a {string}.'], $jsonArray->toArray());
     }
 
     /**
@@ -84,7 +86,7 @@ public function testConvertsArrayHavingSingleElement()
         $jsonArray = new JsonArray('{"success": 1}');
         $expectedXml = '<?xml version="1.0" encoding="UTF-8"?>'
             . "\n<root><success>1</success></root>\n";
-        $this->assertEquals($expectedXml, $jsonArray->toXml()->saveXML());
+        $this->assertSame($expectedXml, $jsonArray->toXml()->saveXML());
     }
 
     public function testConvertsArrayHavingTwoElements()
@@ -92,7 +94,7 @@ public function testConvertsArrayHavingTwoElements()
         $jsonArray = new JsonArray('{"success": 1, "info": "test"}');
         $expectedXml = '<?xml version="1.0" encoding="UTF-8"?>'
             . "\n<root><success>1</success><info>test</info></root>\n";
-        $this->assertEquals($expectedXml, $jsonArray->toXml()->saveXML());
+        $this->assertSame($expectedXml, $jsonArray->toXml()->saveXML());
     }
 
     public function testConvertsArrayHavingSingleSubArray()
@@ -100,6 +102,6 @@ public function testConvertsArrayHavingSingleSubArray()
         $jsonArray = new JsonArray('{"array": {"success": 1}}');
         $expectedXml = '<?xml version="1.0" encoding="UTF-8"?>'
             . "\n<array><success>1</success></array>\n";
-        $this->assertEquals($expectedXml, $jsonArray->toXml()->saveXML());
+        $this->assertSame($expectedXml, $jsonArray->toXml()->saveXML());
     }
 }
diff --git a/tests/unit/Codeception/Util/JsonTypeTest.php b/tests/unit/Codeception/Util/JsonTypeTest.php
index fe2b993..836fe4a 100644
--- a/tests/unit/Codeception/Util/JsonTypeTest.php
+++ b/tests/unit/Codeception/Util/JsonTypeTest.php
@@ -1,9 +1,14 @@
 <?php
+
+declare(strict_types=1);
+
 namespace Codeception\Util;
 
-class JsonTypeTest extends \Codeception\Test\Unit
+use Codeception\Test\Unit;
+
+final class JsonTypeTest extends Unit
 {
-    protected $types = [
+    protected array $types = [
         'id' => 'integer:>10',
         'retweeted' => 'Boolean',
         'in_reply_to_screen_name' => 'null|string',
@@ -12,7 +17,8 @@ class JsonTypeTest extends \Codeception\Test\Unit
             'url' => 'String:url'
         ]
     ];
-    protected $data = [
+
+    protected array $data = [
         'id' => 11,
         'retweeted' => false,
         'in_reply_to_screen_name' => null,
@@ -20,7 +26,7 @@ class JsonTypeTest extends \Codeception\Test\Unit
         'user' => ['url' => 'http://davert.com']
     ];
 
-    public function _after()
+    protected function _after()
     {
         JsonType::cleanCustomFilters();
     }
@@ -138,9 +144,7 @@ public function testNegativeFilters()
 
     public function testCustomFilters()
     {
-        JsonType::addCustomFilter('slug', function ($value) {
-            return strpos($value, ' ') === false;
-        });
+        JsonType::addCustomFilter('slug', fn($value): bool => strpos($value, ' ') === false);
         $jsonType = new JsonType(['title' => 'have a test', 'slug' => 'have-a-test']);
         $this->assertTrue($jsonType->matches([
             'slug' => 'string:slug'
@@ -149,9 +153,7 @@ public function testCustomFilters()
             'title' => 'string:slug'
         ]));
 
-        JsonType::addCustomFilter('/len\((.*?)\)/', function ($value, $len) {
-            return strlen($value) == $len;
-        });
+        JsonType::addCustomFilter('/len\((.*?)\)/', fn($value, $len): bool => strlen($value) == $len);
         $this->assertTrue($jsonType->matches([
             'slug' => 'string:len(11)'
         ]));
@@ -174,7 +176,7 @@ public function testNull()
             "birthdate": null,
             "firstname": "John",
             "lastname": "Doe"
-        }', true));
+        }', true, 512, JSON_THROW_ON_ERROR));
         $this->assertTrue($jsonType->matches([
             'birthdate' => 'string|null'
         ]));
@@ -187,13 +189,13 @@ public function testOR()
     {
         $jsonType = new JsonType(json_decode('{
             "type": "DAY"
-        }', true));
+        }', true, 512, JSON_THROW_ON_ERROR));
         $this->assertTrue($jsonType->matches([
             'type' => 'string:=DAY|string:=WEEK'
         ]));
         $jsonType = new JsonType(json_decode('{
             "type": "WEEK"
-        }', true));
+        }', true, 512, JSON_THROW_ON_ERROR));
         $this->assertTrue($jsonType->matches([
             'type' => 'string:=DAY|string:=WEEK'
         ]));