Configure TestTag to be allowed on a class.

Author: doppynl

README.md

@@ -408,7 +408,7 @@ class AnotherClass extends Result {}
 
 ## TestTag
 
-The `#[TestTag]` attribute is an idea borrowed from hardware testing. Methods marked with this attribute are only available to test code.
+The `#[TestTag]` attribute is an idea borrowed from hardware testing. Classes or methods marked with this attribute are only available to test code.
 
 E.g.
 
@@ -440,7 +440,8 @@ class PersonTest
 ```
 
 NOTES:
-- Methods with the`#[TestTag]` MUST have public visibility.
+- Classes with the `#[TestTag]` will have an error when any interaction with the class is done.
+- Methods with the `#[TestTag]` MUST have public visibility.
 - For determining what is "test code" see the relevant plugin. E.g. the [PHPStan extension](https://github.com/DaveLiddament/phpstan-php-language-extensions) can be setup to either:
     - Assume all classes that end `Test` is test code. See [className config option](https://github.com/DaveLiddament/phpstan-php-language-extensions#exclude-checks-on-class-names-ending-with-test).
     - Assume all classes within a given namespace is test code. See [namespace config option](https://github.com/DaveLiddament/phpstan-php-language-extensions#exclude-checks-based-on-test-namespace).

examples/testTag/testTagOnClass.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace TestTagOnConstructor;
+
+use DaveLiddament\PhpLanguageExtensions\TestTag;
+
+#[TestTag]
+class Person
+{
+    public function __construct()
+    {
+    }
+
+    public static function create(): Person // No Error, class can interact with itself
+    {
+        return new Person(); // No Error, class can interact with itself
+    }
+}
+
+class AnotherClass
+{
+    public function newInstance(): Person
+    {
+        return new Person();
+    }
+
+    public function buildPerson(): Person
+    {
+        return Person::create();
+    }
+}

examples/testTag/testTagOnClassIgnoredInTestClass.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace TestTagOnConstructor;
+
+use DaveLiddament\PhpLanguageExtensions\TestTag;
+
+#[TestTag]
+class Person
+{
+    public function __construct()
+    {
+    }
+
+    public static function create(): Person // No Error, class can interact with itself
+    {
+        return new Person(); // No Error, class can interact with itself
+    }
+}
+
+class PersonTest
+{
+    public function newInstance(): Person
+    {
+        return new Person(); // ERROR
+    }
+
+    public function buildPerson(): Person
+    {
+        return Person::create(); // ERROR
+    }
+}

src/TestTag.php

@@ -5,10 +5,10 @@
 namespace DaveLiddament\PhpLanguageExtensions;
 
 /**
- * Add the TestTag attribute to a method that should only be called by test code.
- * Attempts to call from non-test code will raise an issue.
+ * Add the TestTag attribute to a class or a method that should only be called by test code.
+ * Attempts to use or call from non-test code will raise an issue.
  */
-#[\Attribute(\Attribute::TARGET_METHOD)]
+#[\Attribute(\Attribute::TARGET_CLASS | \Attribute::TARGET_METHOD)]
 final class TestTag
 {
 }