refactored Registry pattern

Structural/Registry/Registry.php

@@ -10,9 +10,9 @@ abstract class Registry
      * this introduces global state in your application which can not be mocked up for testing
      * and is therefor considered an anti-pattern! Use dependency injection instead!
      *
-     * @var array
+     * @var Service[]
      */
-    private static $storedValues = [];
+    private static $services = [];
 
     /**
      * @var array
@@ -21,32 +21,21 @@ abstract class Registry
         self::LOGGER,
     ];
 
-    /**
-     * @param string $key
-     * @param mixed  $value
-     *
-     * @return void
-     */
-    public static function set(string $key, $value)
+    public static function set(string $key, Service $value)
     {
         if (!in_array($key, self::$allowedKeys)) {
             throw new \InvalidArgumentException('Invalid key given');
         }
 
-        self::$storedValues[$key] = $value;
+        self::$services[$key] = $value;
     }
 
-    /**
-     * @param string $key
-     *
-     * @return mixed
-     */
-    public static function get(string $key)
+    public static function get(string $key): Service
     {
-        if (!in_array($key, self::$allowedKeys) || !isset(self::$storedValues[$key])) {
+        if (!in_array($key, self::$allowedKeys) || !isset(self::$services[$key])) {
             throw new \InvalidArgumentException('Invalid key given');
         }
 
-        return self::$storedValues[$key];
+        return self::$services[$key];
     }
 }

Structural/Registry/Service.php

@@ -0,0 +1,9 @@
+<?php
+
+
+namespace DesignPatterns\Structural\Registry;
+
+
+class Service {
+
+}

Structural/Registry/Tests/RegistryTest.php

@@ -3,28 +3,34 @@
 namespace DesignPatterns\Structural\Registry\Tests;
 
 use DesignPatterns\Structural\Registry\Registry;
-use stdClass;
+use DesignPatterns\Structural\Registry\Service;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 
 class RegistryTest extends TestCase
 {
+    /**
+     * @var Service|MockObject
+     */
+    private $service;
+
+    protected function setUp(): void
+    {
+        $this->service = $this->getMockBuilder(Service::class)->getMock();
+    }
+
     public function testSetAndGetLogger()
     {
-        $key = Registry::LOGGER;
-        $logger = new stdClass();
+        Registry::set(Registry::LOGGER, $this->service);
 
-        Registry::set($key, $logger);
-        $storedLogger = Registry::get($key);
-
-        $this->assertSame($logger, $storedLogger);
-        $this->assertInstanceOf(stdClass::class, $storedLogger);
+        $this->assertSame($this->service, Registry::get(Registry::LOGGER));
     }
 
     public function testThrowsExceptionWhenTryingToSetInvalidKey()
     {
         $this->expectException(\InvalidArgumentException::class);
 
-        Registry::set('foobar', new stdClass());
+        Registry::set('foobar', $this->service);
     }
 
     /**