merged branch fabpot/null-services (PR #8582)

This PR was merged into the 2.3 branch.

Discussion
----------

[DependencyInjection] fixed regression where setting a service to null did not trigger a re-creation of the service when getting it (closes #8392)

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #8392
| License       | MIT
| Doc PR        | n/a

Commits
-------

50d0727 [DependencyInjection] fixed regression where setting a service to null did not trigger a re-creation of the service when getting it

src/Symfony/Component/DependencyInjection/Container.php

@@ -184,6 +184,9 @@ class Container implements IntrospectableContainerInterface
     /**
      * Sets a service.
      *
+     * Setting a service to null resets the service: has() returns false and get()
+     * behaves in the same way as if the service was never created.
+     *
      * @param string $id      The service identifier
      * @param object $service The service instance
      * @param string $scope   The scope of the service
@@ -214,6 +217,14 @@ class Container implements IntrospectableContainerInterface
         if (method_exists($this, $method = 'synchronize'.strtr($id, array('_' => '', '.' => '_')).'Service')) {
             $this->$method();
         }
+
+        if (self::SCOPE_CONTAINER !== $scope && null === $service) {
+            unset($this->scopedServices[$scope][$id]);
+        }
+
+        if (null === $service) {
+            unset($this->services[$id]);
+        }
     }
 
     /**

src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php

@@ -135,6 +135,16 @@ class ContainerTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals($foo, $sc->get('foo'), '->set() sets a service');
     }
 
+    /**
+     * @covers Symfony\Component\DependencyInjection\Container::set
+     */
+    public function testSetWithNullResetTheService()
+    {
+        $sc = new Container();
+        $sc->set('foo', null);
+        $this->assertFalse($sc->has('foo'));
+    }
+
     /**
      * @expectedException \InvalidArgumentException
      */