Modernising the Legacy

No one likes to work with the legacy projects - it's not fun. There are no specs, there are no behat examples and you're afraid to touch it. The customer may not have time or budget to spend on rewriting it from the scratch, but is likely to keep asking for the new features.

Learn how to work with the legacy code, how to add new features without breaking existing ones. Learn to use Symfony components to support building sustainable features.

Transcript

1. Modernising the Legacy Marek Matulka UK
2. Marek Matulka Software Engineer SensioLabs UK @super_marek
3. Legacy
4. What is legacy code? - someone else’s code - your old code - an old framework you don’t know - or too coupled to the framework - built over years
5. What is legacy code? Old code where... - most of it is procedural - no namespaces used - no code convention - no separation of concerns
6. What is legacy code? Old code where... - PHP mixed with HTML, CSS - overused Global variables - collection of include files - *.inc files in public folder
7. What is legacy code? Old code where... - no concept of environments - no error reporting - no logging - no version control system used
8. What is legacy code? Any code... - without tests
9. It’s too hard - understand the logic - add new features - debug - fix bugs - adopt new technologies
10. How do we get out of legacy?
11. Start with the goal
12. Why? Business goal
13. Why? Who? Who? Actors
14. Why? Who? Who? How? How? How? Impacts
15. Why? Who? Who? How? How? How? What? What? What? What? What? What? Deliverables
16. Why? Who? Who? How? How? How? What? What? What? What? What? What? Prioritise
17. Goal: Reduce drop-outs by 10% In order to see the total cost of order As a shopper I want to see postage cost Example Why? Who? How? What?
18. Write scenarios Feature: Shopper can see postage cost In order to see the total cost of order As a shopper I want to see a postage cost Scenario: Shopper can see a postage cost Given I have added a "Clean Code" book priced £34.50 to the basket And the postage cost for one book is £3.50 When I check the basket Then I should see the postage cost of £3.50 And the total of the basket should be £38.00
19. Implement scenarios
20. Given-When-Then Feature: Shopper can see postage cost In order to see the total cost of order As a shopper I want to see a postage cost Scenario: Shopper can see a postage cost Given I have added a "Clean Code" book priced £34.50 to the basket And the postage cost for one book is £3.50 When I check the basket Then I should see the postage cost of £3.50 And the total of the basket should be £38.00
21. Write a failing scenario (feature)
22. Write a failing scenario (feature) Write a failing test
23. Write a failing scenario (feature) Write a failing test Make your test pass
24. Write a failing scenario (feature) Write a failing test Make your test pass Refactor your code
25. Write a failing scenario (feature) Write a failing test Make your test pass Refactor your code Repeat the fail-pass-refactor cycle as necessary
26. Write a failing scenario (feature) Write a failing test Make your test pass Refactor your code Make your scenario pass
27. Write a failing scenario (feature) Write a failing test Make your test pass Refactor your code Make your scenario pass BDD TDD
28. Write a failing scenario (feature) Write a failing test Make your test pass Refactor your code Make your scenario pass BDD TDD External Quality Internal Quality
29. (everything?) What to test?
30. Unit tests Acceptance tests Integration tests Smoke tests
31. Unit tests Acceptance tests Integration tests Smoke tests Manual Automated
32. Unit tests Acceptance tests Integration tests Smoke tests Slowest Fastest
33. Why test?
34. Why test? - code level documentation - features described through examples - clean code - you’re not afraid to change your code - peace of mind
35. Why test? delivered features project’s life
36. Why use Symfony components?
37. Symfony Components The standard foundation on which the best PHP applications are built. - fully tested - decoupled - reusable - de-facto standard
38. Symfony Components Build a micro framework. Use components you need in your application.
39. symfony/dependency-injection Dependency Injection
40. Dependency Injection In software engineering, dependency injection is a software design pattern that implements inversion of control for resolving dependencies. Dependency injection means giving an object its instance variables. Really. That's it. https://en.wikipedia.org/wiki/Dependency_injection
41. Dependency Injection PostageCalculator PostageRepository
42. Dependency Inversion PostageCalculator PostageRepository
43. Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository
44. Dependency Inversion PostageCalculator PostageRepository PostageSqliteRepository PostageDoctrineRepository
45. Install dependency injection $ composer require symfony/dependency-injection $ composer require symfony/config
46. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
47. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
48. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
49. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
50. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
51. Create container.php <?php // app/container.php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require __DIR__ . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile();
52. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
53. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
54. # app/config/services.yml services: acme.postage.repository: class: Acme\Infrastructure\Sqlite\PostageSqliteRepository acme.postage.calculator: class: Acme\Basket\PostageCalculator arguments: - @acme.postage.repository Create services.yml
55. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
56. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
57. Use container require '../_inc/db.php'; require '../app/container.php'; // ... $postageCalculator = $container->get('acme.postage.calculator'); if ($postage = $postageCalculator->calculateForBasket($_SESSION['basket'])) { $postage = $postage->toView(); echo sprintf("<p>Estimated postage for %d item(s): £%1.02f.</p>", $postage['quantity'], $postage['price'] ); } // ...
58. Dependency Injection with Drupal 7?
59. container.php <?php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require_once DRUPAL_ROOT . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile(); $conf['di_container'] = $container;
60. container.php <?php use Symfony\Component\DependencyInjection\ContainerBuilder; use Symfony\Component\DependencyInjection\Loader\YamlFileLoader; use Symfony\Component\Config\FileLocator; require_once DRUPAL_ROOT . '/../vendor/autoload.php'; $container = new ContainerBuilder(); $loader = new YamlFileLoader($container, new FileLocator(__DIR__ . '/app/config')); $loader->load('services.yml'); $container->compile(); $conf['di_container'] = $container;
61. depot_locator.module <?php function get_depot_json($postcode) { global $conf; $depotEntity = $conf['di_container'] ->get('acme.depot_locator')->locateDepot($postcode); $depot = $depotEntity->toArray(); set_depot_cookies($depot); return ['depot' => $depot]; }
62. twig/twig Twig
63. What is twig?
64. Install twig $ composer require twig/twig
65. How to use twig? $loader = new Twig_Loader_Filesystem('/path/to/templates'); $twig = new Twig_Environment($loader); echo $twig->render('index.html', ['variable' => 'value']);
66. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
67. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
68. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
69. # app/config/services.yml parameters: twig.paths: - app/Resources/views services: twig.template_loader: class: Twig_Loader_Filesystem arguments: - %twig.paths% twig.renderer: class: Twig_Environment arguments: - @twig.template_loader Enabling twig in DI container
70. Use twig $basketViewData = $container->get('acme.basket.view') ->toView($_SESSION['basket']); $basketView = $container->get('twig.renderer') ->render( 'basket.twig.html', $basketViewData ); echo $basketView;
71. symfony/console Add console commands
72. Install console component $ composer require symfony/console
73. class ImportAndPersistCommand extends Command { private $action; public function __construct(ImportAndPersistActionHandler $action) { $this->action = $action; parent::__construct(); } protected function configure() { $this->setName('products:import'); } protected function execute(InputInterface $input, OutputInterface $output) { $startTime = microtime(true); $this->action->importAndPersistProducts(); $executionTime = microtime(true) - $startTime; $output->writeln( sprintf("Products import completed in %1.02fs.", $executionTime) ); } }
74. app/console #!/usr/bin/php <?php require_once (__DIR__ . '/../vendor/autoload.php'); require_once (__DIR__ . '/app/container.php'); use Symfony\Component\Console\Application; $application = new Application(); $application->addCommands([ $container->get('acme.command.import_products'), $container->get('acme.command.delete_products'), $container->get('acme.command.depot_locate'), ]); $application->run();
75. symfony/http-foundation Decouple from global state
76. Http application’s flow Controller Request Response
77. Install HttpFoundation component $ composer require symfony/http-foundation
78. De-coupling from global state # /public/index.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
79. De-coupling from global state # /public/index.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
80. De-coupling from global state # /public/index.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
81. De-coupling from global state # /public/index.php <?php require __DIR__ . '/../app/container.php'; use Symfony\Component\HttpFoundation\Request; $request = Request::createFromGlobals(); $response = $container->get('acme.basket_view.controller') ->viewAction($request); $response->send();
82. Going forward
83. Try it yourself!
84. Playground https://github.com/mareg/legacy-summercamp-2015 - four exercises: - add dependency injection - add twig - decouple from global state - controller as service
85. Questions? Slides: speakerdeck.com/super_marek Feedback: joind.in/talk/view/14977 Connect: @super_marek