Add phpstan

.github/workflows/on_pull_request.yml

@@ -31,6 +31,10 @@ jobs:
         run: composer validate --strict --no-check-lock
       - name: Install Composer dependencies (with dev)
         run: composer install --no-progress --no-suggest --prefer-dist --optimize-autoloader
+      - name: Run phpcs
+        run: composer phpcs
+      - name: Run phpstan
+        run: composer phpstan
       - name: Install Composer dependencies (without dev)
         run: composer install --no-progress --no-dev --no-suggest --prefer-dist --optimize-autoloader
 

composer.json

@@ -38,10 +38,12 @@
         "sort-packages": true
     },
     "require-dev": {
+        "phpstan/phpstan": "^2.1",
         "squizlabs/php_codesniffer": "^3.7"
     },
     "scripts": {
         "phpcs": "phpcs",
-        "phpcbf": "phpcbf"
+        "phpcbf": "phpcbf",
+        "phpstan": "phpstan analyse"
     }
 }

phpstan.neon

@@ -0,0 +1,10 @@
+parameters:
+    level: 8
+    paths:
+        - src
+
+    # Ignore tests directory for now
+    excludePaths:
+        - vendor/*
+
+    reportUnmatchedIgnoredErrors: false

src/ToArrayInterface.php

@@ -12,7 +12,7 @@ interface ToArrayInterface
     /**
      * Converts object to array
      *
-     * @return array
+     * @return array<string, mixed>
      */
     public function toArray(): array;
 }