Enable StackPHP Support

Add another optional constructor argument so that the entire middleware can be configured when the original object instance is not available. Add tests to make sure that the extra constructor argument for the response header works as expected, and update the README to reflect the changes to the RequestId API including example usage of how to integrate the library with StackPHP.

README.md

@@ -73,3 +73,34 @@ It is also possible to change response header's name:
 ```php5
 $stack->enableResponseHeader('My-Custom-Request-Id');
 ```
+
+If you don't have access to the `RequestId` object instance (StackPHP, for example) the response header can be set via
+the fourth argument of the `RequestId` constructor method.
+
+```php5
+$generator = new UuidRequestIdGenerator(1337);
+$stack = new RequestId($kernel, $generator, 'X-Request-Id', 'My-Custom-Request-Id');
+```
+
+The third argument, for reference, is the name of the header:
+- That will be checked for a value before falling back to generating a new request ID,
+- Used to store the resulting request ID inside Symfony's request object.
+
+## StackPHP's Middleware Builder
+If you are already using [StackPHP](http://stackphp.com), just push the `RequestId` class into the builder.
+
+```php5
+$kernel = new AppKernel('dev', true);
+
+$generator = new UuidRequestIdGenerator(1337);
+$stack = (new Stack\Builder)
+    ->push('Qandidate\Stack\RequestId', $generator, 'X-Request-Id', 'X-Request-Id')
+    ->resolve($kernel);
+
+$kernel->loadClassCache();
+
+$request = Request::createFromGlobals();
+$response = $stack->handle($request);
+$response->send();
+$kernel->terminate($request, $response);
+```

src/Qandidate/Stack/RequestId.php

@@ -25,11 +25,16 @@ class RequestId implements HttpKernelInterface
     private $header;
     private $responseHeader;
 
-    public function __construct(HttpKernelInterface $app, RequestIdGenerator $generator, $header = 'X-Request-Id')
-    {
-        $this->app       = $app;
-        $this->generator = $generator;
-        $this->header    = $header;
+    public function __construct(
+        HttpKernelInterface $app,
+        RequestIdGenerator $generator,
+        $header = 'X-Request-Id',
+        $responseHeader = null
+    ) {
+        $this->app            = $app;
+        $this->generator      = $generator;
+        $this->header         = $header;
+        $this->responseHeader = $responseHeader;
     }
 
     /**

test/Qandidate/Stack/RequestIdTest.php

@@ -99,6 +99,48 @@ public function it_sets_the_request_id_in_a_custom_response_header_if_given()
         $this->assertSame('yolo', $response->headers->get('Request-Id'));
     }
 
+    /**
+     * @test
+     */
+    public function it_can_set_the_response_header_from_the_constructor_argument()
+    {
+        $this->requestIdGenerator->expects($this->any())
+            ->method('generate')
+            ->will($this->returnValue('yolo'));
+
+        $responseHeader = 'Request-Id';
+
+        $this->stackedApp->enableResponseHeader($responseHeader);
+        $normalResponse = $this->stackedApp->handle($this->createRequest());
+
+        $alternateStackedApp = new RequestId($this->app, $this->requestIdGenerator, $this->header, $responseHeader);
+        $alternateResponse = $alternateStackedApp->handle($this->createRequest());
+
+        $this->assertSame('yolo', $alternateResponse->headers->get($responseHeader));
+        $this->assertSame(
+            $normalResponse->headers->get($responseHeader),
+            $alternateResponse->headers->get($responseHeader)
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_override_the_response_header_argument_with_the_response_header_method()
+    {
+        $this->requestIdGenerator->expects($this->any())
+            ->method('generate')
+            ->will($this->returnValue('yolo'));
+
+        $alternateStackedApp = new RequestId($this->app, $this->requestIdGenerator, $this->header, 'Bad-Request-Id');
+        $alternateStackedApp->enableResponseHeader('Good-Request-Id');
+
+        $response = $alternateStackedApp->handle($this->CreateRequest());
+
+        $this->assertFalse($response->headers->has('Bad-Request-Id'));
+        $this->assertTrue($response->headers->has('Good-Request-Id'));
+    }
+
     /**
      * @test
      */