Support Responsable objects.

This is the foundation for allowing objects to be converted into full
HTTP responses, allowing more fluent API packages to be built in the
future.

src/Illuminate/Contracts/Support/Responsable.php

@@ -0,0 +1,13 @@
<?php

namespace Illuminate\Contracts\Support;

interface Responsable
{
    /**
     * Create an HTTP response that represents the object.
     *
     * @return \Illuminate\Http\Response
     */
    public function toResponse();
}

src/Illuminate/Routing/Pipeline.php

@@ -71,7 +71,8 @@ protected function carry()
     */
    protected function handleException($passable, Exception $e)
    {
        if (! $this->container->bound(ExceptionHandler::class) || ! $passable instanceof Request) {
        if (! $this->container->bound(ExceptionHandler::class) ||
            ! $passable instanceof Request) {
            throw $e;
        }

src/Illuminate/Routing/Router.php

@@ -15,6 +15,7 @@
use Illuminate\Contracts\Support\Jsonable;
use Illuminate\Contracts\Events\Dispatcher;
use Illuminate\Contracts\Support\Arrayable;
use Illuminate\Contracts\Support\Responsable;
use Illuminate\Contracts\Routing\BindingRegistrar;
use Psr\Http\Message\ResponseInterface as PsrResponseInterface;
use Illuminate\Contracts\Routing\Registrar as RegistrarContract;
@@ -620,6 +621,8 @@ public static function prepareResponse($request, $response)
    {
        if ($response instanceof PsrResponseInterface) {
            $response = (new HttpFoundationFactory)->createResponse($response);
        } elseif ($response instanceof Responsable) {
            $response = $response->toResponse();
        } elseif (! $response instanceof SymfonyResponse &&
                   ($response instanceof Arrayable ||
                    $response instanceof Jsonable ||

tests/Integration/Routing/ResponsableTest.php

@@ -0,0 +1,33 @@
<?php

use Orchestra\Testbench\TestCase;
use Illuminate\Support\Facades\Route;
use Illuminate\Contracts\Support\Responsable;

/**
 * @group integration
 */
class ResponsableTest extends TestCase
{
    public function test_responsable_objects_are_rendered()
    {
        Route::get('/responsable', function () {
            return new TestResponsableResponse;
        });

        $response = $this->get('/responsable');

        $this->assertEquals(201, $response->status());
        $this->assertEquals('Taylor', $response->headers->get('X-Test-Header'));
        $this->assertEquals('hello world', $response->getContent());
    }
}


class TestResponsableResponse implements Responsable
{
    public function toResponse()
    {
        return response('hello world', 201, ['X-Test-Header' => 'Taylor']);
    }
}