diff --git a/.drone.yml b/.drone.yml
index d41f13a2b..a8e9f8ae6 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -8,7 +8,7 @@ steps:
   - composer install
 
 - name: test
-  image: composer
+  image: hugotty/php8-fpm:latest
   commands:
   - vendor/bin/simple-phpunit
 
diff --git a/composer.json b/composer.json
index 769642299..f3bfda1a7 100644
--- a/composer.json
+++ b/composer.json
@@ -47,7 +47,8 @@
         "phpstan/phpstan-phpunit": "^1.0",
         "phpstan/phpstan-deprecation-rules": "^1",
         "phpstan/phpstan-strict-rules": "^1",
-        "phpstan/phpstan-symfony": "^1.1"
+        "phpstan/phpstan-symfony": "^1.1",
+        "phpmetrics/phpmetrics": "^2.8"
     },
     "suggest": {
         "ext-openssl": "Enabling the openssl extension allows you to access https URLs for repositories and packages",
diff --git a/composer.lock b/composer.lock
index 7d19af4f9..287d3fac0 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "9e35cddef900ba721bf84c8cda25db75",
+    "content-hash": "6838e5c234d90b73527da6a67e3fa2e8",
     "packages": [
         {
             "name": "composer/ca-bundle",
@@ -1823,6 +1823,130 @@
         }
     ],
     "packages-dev": [
+        {
+            "name": "nikic/php-parser",
+            "version": "v4.13.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/nikic/PHP-Parser.git",
+                "reference": "210577fe3cf7badcc5814d99455df46564f3c077"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/210577fe3cf7badcc5814d99455df46564f3c077",
+                "reference": "210577fe3cf7badcc5814d99455df46564f3c077",
+                "shasum": ""
+            },
+            "require": {
+                "ext-tokenizer": "*",
+                "php": ">=7.0"
+            },
+            "require-dev": {
+                "ircmaxell/php-yacc": "^0.0.7",
+                "phpunit/phpunit": "^6.5 || ^7.0 || ^8.0 || ^9.0"
+            },
+            "bin": [
+                "bin/php-parse"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.9-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "PhpParser\\": "lib/PhpParser"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Nikita Popov"
+                }
+            ],
+            "description": "A PHP parser written in PHP",
+            "keywords": [
+                "parser",
+                "php"
+            ],
+            "support": {
+                "issues": "https://github.com/nikic/PHP-Parser/issues",
+                "source": "https://github.com/nikic/PHP-Parser/tree/v4.13.2"
+            },
+            "time": "2021-11-30T19:35:32+00:00"
+        },
+        {
+            "name": "phpmetrics/phpmetrics",
+            "version": "v2.8.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/phpmetrics/PhpMetrics.git",
+                "reference": "e279f7317390f642339941b693359e9a181817a7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/phpmetrics/PhpMetrics/zipball/e279f7317390f642339941b693359e9a181817a7",
+                "reference": "e279f7317390f642339941b693359e9a181817a7",
+                "shasum": ""
+            },
+            "require": {
+                "ext-dom": "*",
+                "ext-tokenizer": "*",
+                "nikic/php-parser": "^3|^4",
+                "php": ">=5.5"
+            },
+            "replace": {
+                "halleck45/php-metrics": "*",
+                "halleck45/phpmetrics": "*"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.8.36 || ^5.7.27 || ^6.5.14",
+                "sebastian/comparator": ">=1.2.3",
+                "squizlabs/php_codesniffer": "^3.5",
+                "symfony/dom-crawler": "^3.0 || ^4.0 || ^5.0"
+            },
+            "bin": [
+                "bin/phpmetrics"
+            ],
+            "type": "library",
+            "autoload": {
+                "files": [
+                    "./src/functions.php"
+                ],
+                "psr-0": {
+                    "Hal\\": "./src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jean-François Lépine",
+                    "email": "lepinejeanfrancois@yahoo.fr",
+                    "homepage": "http://www.lepine.pro",
+                    "role": "Copyright Holder"
+                }
+            ],
+            "description": "Static analyzer tool for PHP : Coupling, Cyclomatic complexity, Maintainability Index, Halstead's metrics... and more !",
+            "homepage": "http://www.phpmetrics.org",
+            "keywords": [
+                "analysis",
+                "qa",
+                "quality",
+                "testing"
+            ],
+            "support": {
+                "issues": "https://github.com/PhpMetrics/PhpMetrics/issues",
+                "source": "https://github.com/phpmetrics/PhpMetrics/tree/v2.8.1"
+            },
+            "time": "2022-03-24T10:19:51+00:00"
+        },
         {
             "name": "phpstan/phpstan",
             "version": "1.6.3",
@@ -2202,5 +2326,5 @@
     "platform-overrides": {
         "php": "7.2.5"
     },
-    "plugin-api-version": "2.3.0"
+    "plugin-api-version": "2.1.0"
 }