Building a Silex application from one Behat/Gherkin feature file

Last days I’ve playing with Behat. Behat is a behavior driven development (BDD) framework based on Ruby’s Cucumber. Basically with Behat we defenie features within one feature file. I’m not going to crate a Behat tutorial (you can read more about Behat here). Behat use Gherkin to write the features files. When I was playing with Behat I had one idea. The idea is simple: Can we use Gherking to build a Silex application?. It was a good excuse to study Gherking, indeed ;).

Here comes the feature file:

Feature: application API
  Scenario: List users
    Given url "/api/users/list.json"
    And request method is "GET"
    Then instance "\Api\Users"
    And execute function "listUsers"
    And format output into json

  Scenario: Get user info
    Given url "/api/user/{userName}.json"
    And request method is "GET"
    Then instance "\Api\User"
    And execute function "info"
    And format output into json

  Scenario: Update user information
    Given url "/api/user/{userName}.json"
    And request method is "POST"
    Then instance "\Api\User"
    And execute function "update"
    And format output into json

Our API use this simple library:

<?php

namespace Api;
use Symfony\Component\HttpFoundation\Request;

class User
{
    private $request;

    public function __construct(Request $request)
    {
        $this->request = $request;
    }

    public function info()
    {
        switch ($this->request->get('userName')) {
            case 'gonzalo':
                return array('name' => 'Gonzalo', 'surname' => 'Ayuso');
            case 'peter':
                return array('name' => 'Peter', 'surname' => 'Parker');
        }
    }

    public function update()
    {
        return array('infoUpdated');
    }
}

<?php

namespace Api;
use Symfony\Component\HttpFoundation\Request;

class Users
{
    public function listUsers()
    {
        return array('gonzalo', 'peter');
    }
}

The idea is simple. Parse the feature file with behat/gherkin component and create a silex application. And here comes the “magic”. This is a simple working prototype, just an experiment for a rainy sunday.

<?php
include __DIR__ . '/../vendor/autoload.php';
define(FEATURE_PATH, __DIR__ . '/api.feature');

use Behat\Gherkin\Lexer,
        Behat\Gherkin\Parser,
        Behat\Gherkin\Keywords\ArrayKeywords,
        Behat\Gherkin\Node\FeatureNode,
        Behat\Gherkin\Node\ScenarioNode,
        Symfony\Component\HttpFoundation\Request,
        Silex\Application;

$keywords = new ArrayKeywords([
    'en' => [
        'feature' => 'Feature',
        'background' => 'Background',
        'scenario' => 'Scenario',
        'scenario_outline' => 'Scenario Outline',
        'examples' => 'Examples',
        'given' => 'Given',
        'when' => 'When',
        'then' => 'Then',
        'and' => 'And',
        'but' => 'But'
    ],
]);

function getMatch($subject, $pattern) {
    preg_match($pattern, $subject, $matches);
    return isset($matches[1]) ? $matches[1] : NULL;
}

$app = new Application();

function getScenarioConf($scenario) {
    $silexConfItem = [];

    /** @var $scenario  ScenarioNode */
    foreach ($scenario->getSteps() as $step) {
        $route = getMatch($step->getText(), '/^url "([^"]*)"$/');

        if (!is_null($route)) {
            $silexConfItem['route'] = $route;
        }

        $requestMethod = getMatch($step->getText(), '/^request method is "([^"]*)"$/');
        if (!is_null($requestMethod)) {
            $silexConfItem['requestMethod'] = strtoupper($requestMethod);
        }

        $instance = getMatch($step->getText(), '/^instance "([^"]*)"$/');
        if (!is_null($instance)) {
            $silexConfItem['className'] = $instance;
        }

        $method = getMatch($step->getText(), '/^execute function "([^"]*)"$/');
        if (!is_null($method)) {
            $silexConfItem['method'] = $method;
        }

        if ($step->getText() == 'format output into json') {
            $silexConfItem['jsonEncode'] = TRUE;
        }
    }
    return $silexConfItem;
}

/** @var $features FeatureNode */
$features = (new Parser(new Lexer($keywords)))->parse(file_get_contents(FEATURE_PATH), FEATURE_PATH);

foreach ($features->getScenarios() as $scenario) {
    $silexConfItem = getScenarioConf($scenario);
    $app->match($silexConfItem['route'], function (Request $request) use ($app, $silexConfItem) {
            function getConstructorParams($rClass, $request) {
                $parameters =[];
                foreach ($rClass->getMethod('__construct')->getParameters() as $parameter) {
                    if ('Symfony\Component\HttpFoundation\Request' == $parameter->getClass()->name) {
                        $parameters[$parameter->getName()] = $request;
                    }
                }
                return $parameters;
            }

            $rClass = new ReflectionClass($silexConfItem['className']);
            $obj = ($rClass->hasMethod('__construct')) ?
                    $rClass->newInstanceArgs(getConstructorParams($rClass, $request)) :
                    new $silexConfItem['className'];

            $output = $obj->{$silexConfItem['method']}();

            return ($silexConfItem['jsonEncode'] === TRUE) ? $app->json($output, 200) : $output;
        }
    )->method($silexConfItem['requestMethod']);
}

$app->run();

You can see the source code in github. What do you think?