Implement bootstrap loading

features/configuration/loading_configured_bootstrap_file.feature

@@ -0,0 +1,56 @@
+Feature: Loading configured bootstrap file
+
+    Scenario: Loading configured bootstrap file
+        Given a working Symfony application with SymfonyExtension configured
+        And a Behat configuration containing:
+        """
+        default:
+            extensions:
+                FriendsOfBehat\SymfonyExtension:
+                    bootstrap: custom/bootstrap.php
+
+            suites:
+                default:
+                    contexts:
+                        - App\Tests\SomeContext
+        """
+        And a boostrap file "custom/bootstrap.php" containing:
+        """
+        <?php
+
+        putenv("CUSTOM_VARIABLE=lol2");
+        $_SERVER['CUSTOM_VARIABLE'] = $_ENV['CUSTOM_VARIABLE'] = 'lol2';
+        """
+        And a context file "tests/SomeContext.php" containing:
+        """
+        <?php
+
+        namespace App\Tests;
+
+        use Behat\Behat\Context\Context;
+
+        final class SomeContext implements Context {
+            private $parameter;
+
+            public function __construct(?string $parameter = null) { $this->parameter = $parameter; }
+
+            /** @Then the passed parameter should be :expected */
+            public function parameterShouldBe(string $expected): void { assert($this->parameter === $expected); }
+        }
+        """
+        And a YAML services file containing:
+        """
+        services:
+            App\Tests\SomeContext:
+                public: true
+                arguments:
+                    - "%env(CUSTOM_VARIABLE)%"
+        """
+        And a feature file containing:
+        """
+        Feature:
+            Scenario:
+                Then the passed parameter should be "lol2"
+        """
+        When I run Behat
+        Then it should pass

src/ServiceContainer/SymfonyExtension.php

@@ -51,7 +51,9 @@ final class SymfonyExtension implements Extension
     public function configure(ArrayNodeDefinition $builder): void
     {
         $builder
+            ->addDefaultsIfNotSet()
             ->children()
+                ->scalarNode('bootstrap')->defaultNull()->end()
                 ->arrayNode('kernel')
                     ->addDefaultsIfNotSet()
                     ->children()
@@ -67,7 +69,9 @@ final class SymfonyExtension implements Extension
 
     public function load(ContainerBuilder $container, array $config): void
     {
-        $this->loadKernel($container, $this->processKernelConfiguration($config['kernel']));
+        $container->setParameter('fob_symfony.bootstrap', $config['bootstrap']);
+
+        $this->loadKernel($container, $this->autodiscoverKernelConfiguration($config['kernel']));
         $this->loadDriverKernel($container);
 
         $this->loadKernelRebooter($container);
@@ -82,6 +86,7 @@ final class SymfonyExtension implements Extension
 
     public function process(ContainerBuilder $container): void
     {
+        $this->processBootstrap($container->getParameter('fob_symfony.bootstrap'));
     }
 
     private function registerMinkDriver(ExtensionManager $extensionManager): void
@@ -157,7 +162,7 @@ final class SymfonyExtension implements Extension
         $container->setDefinition('fob_symfony.mink.parameters', $minkParametersDefinition);
     }
 
-    private function processKernelConfiguration(array $config): array
+    private function autodiscoverKernelConfiguration(array $config): array
     {
         if ($config['class'] !== null) {
             return $config;
@@ -187,4 +192,13 @@ final class SymfonyExtension implements Extension
 
         return $config;
     }
+
+    private function processBootstrap(?string $bootstrap): void
+    {
+        if ($bootstrap === null) {
+            return;
+        }
+
+        require_once $bootstrap;
+    }
 }