bug #32056 [DI] deprecate booting the kernel twices (Simperfit)

This PR was merged into the 4.4 branch.

Discussion
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[DI] deprecate booting the kernel twices

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | yes <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #31233   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | ? <!-- required for new features -->

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Additionally (see https://symfony.com/roadmap):
 - Bug fixes must be submitted against the lowest maintained branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too).
 - Features and deprecations must be submitted against branch 4.4.
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This adds a check to see if the kernel has been booted twices in a single test, and throw a deprecation

Commits
-------

905bec4577 [DI] throw an exception when the kernel has been booted twices

Author: fabpot

CHANGELOG.md

@@ -9,6 +9,7 @@ CHANGELOG
  * Deprecated the `controller_name_converter` and `resolve_controller_name_subscriber` services
  * The `ControllerResolver` and `DelegatingLoader` classes have been marked as `final`
  * Added support for configuring chained cache pools
+ * Deprecated booting the kernel before running `WebTestCase::createClient()`
 
 4.3.0
 -----

Test/KernelTestCase.php

@@ -37,6 +37,8 @@ abstract class KernelTestCase extends TestCase
      */
     protected static $container;
 
+    protected static $booted;
+
     protected function doTearDown(): void
     {
         static::ensureKernelShutdown();
@@ -72,6 +74,7 @@ protected static function bootKernel(array $options = [])
 
         static::$kernel = static::createKernel($options);
         static::$kernel->boot();
+        static::$booted = true;
 
         $container = static::$kernel->getContainer();
         static::$container = $container->has('test.service_container') ? $container->get('test.service_container') : $container;
@@ -126,6 +129,7 @@ protected static function ensureKernelShutdown()
         if (null !== static::$kernel) {
             $container = static::$kernel->getContainer();
             static::$kernel->shutdown();
+            static::$booted = false;
             if ($container instanceof ResetInterface) {
                 $container->reset();
             }

Test/WebTestCase.php

@@ -39,6 +39,10 @@ protected function doTearDown(): void
      */
     protected static function createClient(array $options = [], array $server = [])
     {
+        if (true === static::$booted) {
+            @trigger_error(sprintf('Booting the kernel before calling %s::%s is deprecated and will throw in Symfony 5.0, the kernel should only be booted once.', __CLASS__, __METHOD__), E_USER_DEPRECATED);
+        }
+
         $kernel = static::bootKernel($options);
 
         try {

Tests/Functional/SessionTest.php

@@ -83,6 +83,8 @@ public function testTwoClients($config, $insulate)
             $client1->insulate();
         }
 
+        $this->ensureKernelShutdown();
+
         // start second client
         $client2 = $this->createClient(['test_case' => 'Session', 'root_config' => $config]);
         if ($insulate) {