Add architectural tests with PHPat

tests/Architecture/ArchTest.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Tests\Architecture;
+
+use Drupal\Core\Controller\ControllerBase;
+use PHPat\Selector\Selector;
+use PHPat\Test\Builder\Rule;
+use PHPat\Test\PHPat;
+
+final class ArchTest {
+
+  public function test_classes_should_be_final(): Rule {
+    return PHPat::rule()
+      ->classes(Selector::inNamespace('Drupal\atdc'))
+      ->shouldBeFinal();
+  }
+
+  public function test_controllers_should_extend_ControllerBase(): Rule {
+    return PHPat::rule()
+      ->classes(Selector::inNamespace('Drupal\atdc\Controller'))
+      ->shouldExtend()
+      ->classes(Selector::classname(ControllerBase::class));
+  }
+
+  public function test_controllers_should_have_the_Controller_suffix(): Rule {
+    return PHPat::rule()
+      ->classes(Selector::inNamespace('Drupal\atdc\Controller'))
+      ->shouldBeNamed(
+        classname: '/Controller$/',
+        regex: TRUE,
+      );
+  }
+
+}