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docs/02_usage.md

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+## Usage
+
+This tutorial assumes you're using the new directory structure with autowiring and autoconfiguration enabled.
+Let's first create a sample feature file (which is quite useless for demo purposes):
+
+```gherkin
+Feature: Using SymfonyExtension
+
+    Scenario: Checking the application's kernel environment
+        Then the application's kernel should use "test" environment
+``` 
+
+There are two methods to check the kernel's environment - either by calling `getEnviornment()` method on the kernel itself 
+or by injecting `%kernel.environment%` parameter.
+
+We'll need also a dummy context implementation:
+
+```php
+<?php
+
+# tests/Behat/DemoContext.php
+
+namespace App\Tests\Behat;
+// If using Symfony 3, use namespace "Tests\Behat" instead
+
+use Behat\Behat\Context\Context;
+
+final class DemoContext implements Context
+{
+    /**
+     * @Then the application's kernel should use :expected environment 
+     */
+    public function kernelEnvironmentShouldBe(string $expected): void
+    {
+    }
+}
+```
+
+And also a suite defined in Behat configuration:
+
+```yaml
+# behat.yml.dist / behat.yml
+
+default:
+    suites:
+        default:
+            contexts:
+                - App\Tests\Behat\DemoContext
+
+```
+
+After running Behat, the scenario should be passing.
+
+### Services injection
+
+Modify the existing `DemoContext` to be able to inject a kernel instance:
+
+```php
+<?php
+
+// ...
+
+use Symfony\Component\HttpKernel\KernelInterface;
+
+final class DemoContext implements Context
+{
+    /** @var KernelInterface */
+    private $kernel;
+    
+    public function __construct(KernelInterface $kernel) 
+    {
+        $this->kernel = $kernel;
+    }
+
+    /**
+     * @Then the application's kernel should use :expected environment 
+     */
+    public function kernelEnvironmentShouldBe(string $expected): void
+    {
+        if ($this->kernel->getEnvironment() !== $expected) {
+            throw new \RuntimeException();
+        }
+    }
+}
+```
+
+If you're using autowiring and autoconfiguration, that's all you need! After running Behat, you should see a passing scenario.
+
+If you're not, you need to register your context as a public service and define its dependencies:
+
+```yaml
+# config/services_test.yaml (Symfony 4)
+# app/config/config_test.yml (Symfony 3)
+
+services:
+    App\Tests\DemoContext:
+        public: true
+        arguments:
+            - "@kernel"
+```
+
+### Parameters injection
+
+Modify the existing `DemoContext` to be able to inject a kernel environment as a parameter:
+
+```php
+<?php
+
+// ...
+
+final class DemoContext implements Context
+{
+    /** @var string */
+    private $environment;
+    
+    public function __construct(string $environment) 
+    {
+        $this->environment = $environment;
+    }
+
+    /**
+     * @Then the application's kernel should use :expected environment 
+     */
+    public function kernelEnvironmentShouldBe(string $expected): void
+    {
+        if ($this->environment !== $expected) {
+            throw new \RuntimeException();
+        }
+    }
+}
+```
+
+If you're using autowiring and autoconfiguration, that's all you need! After running Behat, you should see a passing scenario.
+
+If you're not, you need to register your context as a public service and define its dependencies:
+
+```yaml
+# config/services_test.yaml (Symfony 4)
+# app/config/config_test.yml (Symfony 3)
+
+services:
+    App\Tests\DemoContext:
+        public: true
+        arguments:
+            - "%kernel.environment%"
+```