Add support to extensions on aliases

Author: coisa

src/ServiceProviderContainer.php

@@ -86,16 +86,49 @@ public function get(string $id): mixed
         }
 
         try {
-            $service    = $factory[$id]($this->wrapperContainer);
-            $extensions = $this->serviceProvider->getExtensions();
-
-            if (\array_key_exists($id, $extensions) && \is_callable($extensions[$id])) {
-                $extensions[$id]($this->wrapperContainer, $service);
-            }
+            $service = call_user_func($factory[$id], $this->wrapperContainer);
+            $this->applyServiceExtensions($id, $service);
         } catch (ContainerExceptionInterface $containerException) {
             throw ContainerException::forInvalidService($id, $containerException);
         }
 
         return $this->cache[$id] = $service;
     }
+
+    /**
+     * Applies service extensions to the constructed service instance.
+     *
+     * This method SHALL inspect the set of extensions returned by the service provider,
+     * checking both the original service identifier and the concrete class name of the
+     * service instance. If a corresponding extension is found, it MUST be a callable and
+     * SHALL be invoked with the container and service instance as arguments.
+     *
+     * This mechanism allows for post-construction decoration or augmentation of the
+     * resolved service. Extensions MAY be used to modify or enhance the behavior or state
+     * of services after they have been created.
+     *
+     * Implementations MUST ensure that only valid callables are executed and SHOULD avoid
+     * side effects beyond service enhancement. If an extension fails or is not callable,
+     * the method SHALL silently ignore it unless explicitly configured otherwise.
+     *
+     * @param string $id      The identifier of the resolved service.
+     * @param mixed  $service The service instance to be extended.
+     *
+     * @return void
+     *
+     * @throws ContainerException If any extension fails during invocation.
+     */
+    private function applyServiceExtensions(string $id, mixed $service): void
+    {
+        $class = get_class($service);
+        $extensions = $this->serviceProvider->getExtensions();
+
+        if (\array_key_exists($id, $extensions) && \is_callable($extensions[$id])) {
+            $extensions[$id]($this->wrapperContainer, $service);
+        }
+
+        if ($id !== $class && \array_key_exists($class, $extensions) && \is_callable($extensions[$class])) {
+            $extensions[$class]($this->wrapperContainer, $service);
+        }
+    }
 }

tests/ServiceProviderContainerTest.php

@@ -138,4 +138,63 @@ public function testGetWillReturnFromCacheWhenSericeAlreadyResolved(): void
 
         self::assertSame($service, $this->container->get('foo'));
     }
+
+    public function testApplyServiceExtensionByClassName(): void
+    {
+        $service = new class() {
+            public bool $extended = false;
+        };
+
+        $extension = static function (ContainerInterface $c, object $service): void {
+            $service->extended = true;
+        };
+
+        $this->provider->getFactories()->willReturn(['service.id' => static fn () => $service]);
+        $this->provider->getExtensions()->willReturn([get_class($service) => $extension]);
+
+        $resolved = $this->container->get('service.id');
+
+        self::assertTrue($resolved->extended);
+    }
+
+    public function testApplyServiceExtensionByIdAndClass(): void
+    {
+        $service = new class() {
+            public array $calls = [];
+        };
+
+        $byIdExtension = static function (ContainerInterface $c, object $service): void {
+            $service->calls[] = 'id';
+        };
+
+        $byClassExtension = static function (ContainerInterface $c, object $service): void {
+            $service->calls[] = 'class';
+        };
+
+        $this->provider->getFactories()->willReturn(['dual' => static fn () => $service]);
+        $this->provider->getExtensions()->willReturn([
+            'dual' => $byIdExtension,
+            get_class($service) => $byClassExtension,
+        ]);
+
+        $resolved = $this->container->get('dual');
+
+        self::assertSame(['id', 'class'], $resolved->calls);
+    }
+
+    public function testApplyServiceIgnoresNonCallableExtensions(): void
+    {
+        $service = new \stdClass();
+
+        $this->provider->getFactories()->willReturn(['not.callable' => static fn () => $service]);
+        $this->provider->getExtensions()->willReturn([
+            'not.callable' => 'not_a_function',
+            get_class($service) => 123,
+        ]);
+
+        $resolved = $this->container->get('not.callable');
+
+        self::assertSame($service, $resolved); // Should still return the service
+        self::assertObjectNotHasProperty('extended', $resolved); // No extension applied
+    }
 }