PHPStan: enable more checks (#23)

Author: janedbal

composer.json

@@ -16,6 +16,7 @@
         "phpstan/phpstan-phpunit": "^1.3.3",
         "phpstan/phpstan-strict-rules": "^1.4.5",
         "phpunit/phpunit": "^9.5.28",
+        "shipmonk/phpstan-rules": "^2.2.0",
         "slevomat/coding-standard": "^8.8.0"
     },
     "autoload": {

phpstan.neon.dist

@@ -4,6 +4,7 @@ includes:
     - ./vendor/phpstan/phpstan-strict-rules/rules.neon
     - ./vendor/phpstan/phpstan-phpunit/extension.neon
     - ./vendor/phpstan/phpstan-phpunit/rules.neon
+    - ./vendor/shipmonk/phpstan-rules/rules.neon
 
 parameters:
     paths:
@@ -13,3 +14,7 @@ parameters:
     checkMissingCallableSignature: true
     checkUninitializedProperties: true
     checkTooWideReturnTypesInProtectedAndPublicMethods: true
+
+    shipmonkRules:
+        enforceReadonlyPublicProperty:
+            enabled: false # it simplifies tests a bit