bug #39268 [HttpClient] Use decoration instead of class replacement for mock factory (GaryPEGEOT)

This PR was squashed before being merged into the 5.2 branch.

Discussion
----------

[HttpClient] Use decoration instead of class replacement for mock factory

| Q             | A
| ------------- | ---
| Branch?       | 5.2
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #39266
| License       | MIT

Commits
-------

9a9823c99a [HttpClient] Use decoration instead of class replacement for mock factory

Author: nicolas-grekas

DependencyInjection/FrameworkExtension.php

@@ -2069,8 +2069,8 @@ private function registerHttpClientConfiguration(array $config, ContainerBuilder
         }
 
         if ($responseFactoryId = $config['mock_response_factory'] ?? null) {
-            $container->getDefinition($httpClientId)
-                ->setClass(MockHttpClient::class)
+            $container->register($httpClientId.'.mock_client', MockHttpClient::class)
+                ->setDecoratedService($httpClientId, null, -10) // lower priority than TraceableHttpClient
                 ->setArguments([new Reference($responseFactoryId)]);
         }
     }

Tests/DependencyInjection/FrameworkExtensionTest.php

@@ -1617,14 +1617,15 @@ public function testHttpClientMockResponseFactory()
     {
         $container = $this->createContainerFromFile('http_client_mock_response_factory');
 
-        $definition = $container->getDefinition('http_client');
+        $definition = $container->getDefinition('http_client.mock_client');
 
         $this->assertSame(MockHttpClient::class, $definition->getClass());
         $this->assertCount(1, $definition->getArguments());
 
         $argument = $definition->getArgument(0);
 
         $this->assertInstanceOf(Reference::class, $argument);
+        $this->assertSame('http_client', current($definition->getDecoratedService()));
         $this->assertSame('my_response_factory', (string) $argument);
     }