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Best practices for crafting high quality PHP apps (PHP Yorkshire 2018)

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This prototype works, but it’s not pretty, and now it’s in production. That legacy application really needs some TLC. Where do we start? When creating long lived applications, it’s imperative to focus on good practices. The solution is to improve the whole development life cycle; from planning, better coding and testing, to automation, peer review and more. In this tutorial, we’ll take a deep dive into each of these areas, looking at how we can make positive, actionable change in our workflow.

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Best practices for crafting high quality PHP apps (PHP Yorkshire 2018)

  1. 1. @asgrim Best practices for crafting high quality PHP apps James Titcumb PHP Yorkshire 2018
  2. 2. $ whoami James Titcumb www.jamestitcumb.com www.roave.com @asgrim
  3. 3. @asgrim
  4. 4. @asgrim What is “quality”?
  5. 5. @asgrim photo: Rob Allen https://flic.kr/p/qmGpsq
  6. 6. @asgrim photo: https://goo.gl/QHWXQL
  7. 7. @asgrim photo: Rob Allen https://flic.kr/p/ecFbH8
  8. 8. @asgrim Quality.
  9. 9. @asgrim "The best code is no code at all” -- Jeff Atwood source: https://blog.codinghorror.com/the-best-code-is-no-code-at-all/
  10. 10. @asgrim Trade-offs.
  11. 11. @asgrim Prototyping & short-lived apps/sites
  12. 12. @asgrim Products Long-lived projects. Open source software.
  13. 13. @asgrim What is quality in applications?
  14. 14. @asgrim What about time/cost…?
  15. 15. @asgrim “A freelancer at $25 an hour for 100 hours still costs more than a freelancer at $150 an hour that takes 10 hours to do the same task” -- Brandon Savage source: http://www.brandonsavage.net/earning-more-money-as-a-php-freelancer/
  16. 16. @asgrim Get an expert in.
  17. 17. @asgrim Complexity
  18. 18. @asgrim Processes
  19. 19. @asgrim This talk... ● Planning ● Development ● Testing ● Continuous integration ● Code reviews ● Deployments
  20. 20. @asgrim Planning
  21. 21. @asgrim Planning is communication
  22. 22. @asgrim Use business terminology
  23. 23. @asgrim Explore and discover
  24. 24. @asgrim Build a model of the business
  25. 25. @asgrim
  26. 26. @asgrim
  27. 27. @asgrim The model must be fluid.
  28. 28. @asgrim “Estimates”
  29. 29. @asgrim Development
  30. 30. @asgrim Care about code
  31. 31. @asgrim “There are only two hard things in Computer Science: cache invalidation and naming things.” -- Phil Karlton source: https://martinfowler.com/bliki/TwoHardThings.html
  32. 32. @asgrim SimpleBeanFactoryAwareAspectInstanceFactory
  33. 33. @asgrim Loader
  34. 34. @asgrim Describe intent
  35. 35. @asgrim “Give awkward names to awkward concepts” -- Eric Evans source: https://skillsmatter.com/conferences/8231-ddd-exchange-2017
  36. 36. @asgrim SOLID
  37. 37. @asgrim KISS
  38. 38. @asgrim Object Calisthenics
  39. 39. @asgrim Avoid early abstraction
  40. 40. @asgrim “Code for your use-case, not for your re-use-case” -- Marco Pivetta source: https://ocramius.github.io/extremely-defensive-php/#/39
  41. 41. @asgrim Care about your API
  42. 42. @asgrim A public method is like a child: once you've written it, you are going to maintain it for the rest of its life! -- Stefan Priebsch
  43. 43. @asgrim Strict type declarations. Use declare(strict_types=1); by default
  44. 44. @asgrim Immutable value objects declare(strict_types=1); use AssertAssertion; // beberlei/assert library ! final class PostalCode { private const VALIDATION_EXPRESSION = '(GIR 0AA)|((([A-Z-[QVX]][0-9][0-... /** @var string */ private $value; public function __construct(string $value) { $this->assertValidPostalCode($value); $this->value = $value; } private function assertValidPostalCode(string $value) : string { Assertion::regex($value, self::VALIDATION_EXPRESSION); } public function __toString() : string { return $this->value; } }
  45. 45. @asgrim Value objects are valid! declare(strict_types=1); final class Thing { public function assignPostalCode(PostalCode $postalCode) : void { // ... we can trust $postalCode is a valid postal code } } // 12345 is not valid - EXCEPTION! $myThing->assignPostalCode(new PostalCode('12345')); // assignPostalCode is happy $myThing->assignPostalCode(new PostalCode('PO1 1AA')); // With STRICT types, this will also FAIL $myThing->assignPostalCode(new PostalCode(12345));
  46. 46. @asgrim Testing
  47. 47. @asgrim Testing is NOT a separate line item
  48. 48. @asgrim Testing should be an assumption
  49. 49. @asgrim You’re already testing.
  50. 50. @asgrim Still need convincing?
  51. 51. @asgrim How?
  52. 52. @asgrim Reduce complexity
  53. 53. @asgrim Reduce complexity public function process(Stuff a, string b, int c) : MoreStuff { // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code // lots of complicated code
  54. 54. @asgrim Reduce complexity public function meaningfulThing(Stuff a, string b, int c) : More { // call nicer, meaningful methods below } private function throwStuffIntoFire(Stuff a) : Fire { // smaller, meaningful chunk of code } private function combineStringWithFire(Fire a, string b) : string { // simple, lovely code! } private function postFlowersToSpain(int c) : void
  55. 55. @asgrim More complexity = more tests
  56. 56. @asgrim Test coverage
  57. 57. @asgrim Line coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true);
  58. 58. @asgrim Line coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true);
  59. 59. @asgrim Branch coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true);
  60. 60. @asgrim Branch coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true);
  61. 61. @asgrim Branch coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true); foo(false, false); // NEW TEST!!!
  62. 62. @asgrim Branch coverage <?php function foo(bool $a, bool $b) { if ($a) { echo "A"; } if ($b) { echo "B"; } } // generate coverage using calls: foo(true, false); foo(false, true); foo(false, false); // NEW TEST!!! foo(true, true); // NEW TEST!!!
  63. 63. @asgrim Prevent coverage leaking
  64. 64. @asgrim Prevent coverage leaking <?php namespace Foo; /** * @covers FooBar */ final class BarTest extends TestCase { // write some tests! }
  65. 65. @asgrim Are the tests testing?
  66. 66. @asgrim Example of a test not testing… public function testPurchaseTickets() { $event = Event::create(uniq('event', true) $customer = Customer::create(uniq('name', true)); $shop->purchaseTicket(1, $event, [$customer]); } @asgrim
  67. 67. @asgrim Assert you’re asserting public function testPurchaseTickets() { $event = Event::create(uniq('event', true) $customer = Customer::create(uniq('name', true)); $receipt = $shop->purchaseTicket(1, $event, [$customer]); self::assertSame($event, $receipt->event()); $customersInReceipt = $receipt->customers(); self::assertCount(1, $customersInReceipt); self::assertContains($customer, $customersInReceipt); } @asgrim
  68. 68. @asgrim Test the tests are testing!
  69. 69. @asgrim Mutation testing function add(int $a, int $b) : int { return $a + $b; } function testAdd() { $result = add(2, 3); // self::assertSame(5, $result); }
  70. 70. @asgrim Mutation testing function add(int $a, int $b) : int { return $a - $b; } function testAdd() { $result = add(2, 3); // self::assertSame(5, $result); }
  71. 71. @asgrim Mutation testing function add(int $a, int $b) : int { return $a - $b; } function testAdd() { $result = add(2, 3); self::assertSame(5, $result); // /// test will now fail with mutation }
  72. 72. @asgrim What about other tests?
  73. 73. @asgrim Integration tests
  74. 74. @asgrim Behaviour tests
  75. 75. @asgrim BAD! Do not do this. Feature: Ability to print my boarding pass Scenario: A checked in passenger can print their boarding pass Given I have a flight booked And I have checked in When I visit the home page And I click the ".manage-booking" button And I enter "CJM23L" in the ".bref-ipt-fld" field And I click the "Find Booking" button Then I should see the ".booking-ref.print" button When I click the ".booking-ref.print" button Then I should see the print dialogue
  76. 76. @asgrim Better Behaviour test Feature: Ability to print my boarding pass Policies: - Boarding passes are only available when already checked in - If customer cannot print boarding pass, they can collect at The airport - more business rules etc... Scenario: A checked in passenger can print their boarding pass Given I have a flight booked for LHR-MIA on 24th May And I have previously checked in for the flight When I display my booking reference "CJM23L" Then I should be able to print my boarding pass And the boarding pass should display flight details correctly
  77. 77. @asgrim Why is this important?
  78. 78. @asgrim Automate these tests
  79. 79. @asgrim Automated tests Application (and UI, API, etc.) Domain / Business Logic Infrastructure (DBAL, APIs, etc.)
  80. 80. @asgrim Automated tests Application (and UI, API, etc.) Domain / Business Logic Infrastructure (DBAL, APIs, etc.)
  81. 81. @asgrim Testing at domain layer Application (UI, API, etc.) Domain / Business Logic Infrastructure (DB, APIs, etc.) // Testing via the UI public function iDisplayMyBookingReference(string $reference) { $page = $this->getSession()->getPage(); $page->click(".manage-booking"); $page->findField(".bref-ipt-fld")->setValue($reference); $page->click("Find Booking"); } // Using the domain layer directly in tests public function iDisplayMyBookingReference(string $reference) { $this->booking = $this->retrieveBooking($reference); }
  82. 82. @asgrim Some UI testing is okay!!! Feature: Ability to print my boarding pass Policies: - Boarding passes are only available when already checked in - If customer cannot print boarding pass, they can collect at The airport - more business rules etc... @ui Scenario: A checked in passenger can print their boarding pass Given I have a flight booked for LHR-OTP on 24th May And I have previously checked in for the flight When I display my booking reference "CJM23L" Then I should be able to print my boarding pass And the boarding pass should display flight details correctly
  83. 83. @asgrim Automate all the things!
  84. 84. @asgrim Continuous Integration
  85. 85. @asgrim Tests cost money to run (manually)
  86. 86. @asgrim Travis-CI.com
  87. 87. @asgrim Jenkins
  88. 88. @asgrim What to automate?
  89. 89. @asgrim The goal?
  90. 90. @asgrim Code reviews
  91. 91. @asgrim What to look for in code review?
  92. 92. @asgrim What to look for in code review? Code style.
  93. 93. @asgrim What to look for in code review? Small, atomic changes.
  94. 94. @asgrim What to look for in code review? Composer versions.
  95. 95. @asgrim What to look for in code review? Structure & good practices.
  96. 96. @asgrim What to look for in code review? Tests.
  97. 97. @asgrim What to look for in code review? Documentation.
  98. 98. @asgrim What to look for in code review? Security.
  99. 99. @asgrim What to look for in code review? Insight.
  100. 100. @asgrim It takes practice.
  101. 101. @asgrim Deployments
  102. 102. @asgrim Automate deployments!
  103. 103. @asgrim One-click deployments
  104. 104. @asgrim “Move fast and break things” -- a stupid Facebook mantra
  105. 105. @asgrim “Move fast and break things with stable infra” -- Facebook mantra since 2014
  106. 106. @asgrim Continuous Delivery & Deployment
  107. 107. @asgrim Better quality
  108. 108. @asgrim Better quality = Higher confidence
  109. 109. @asgrim Better quality = Higher confidence = Happy customers
  110. 110. Any questions? James Titcumb @asgrim
  111. 111. @asgrim Resources ● Event Storming - Alberto Brandolini ○ http://ziobrando.blogspot.co.uk/2013/11/introducing-event-storming.html ● “Good Design is Imperfect Design” - Eric Evans ○ https://skillsmatter.com/skillscasts/9171-good-design-is-imperfect-design ● “Writing code that lasts” - Rafael Dohms ○ https://www.youtube.com/watch?v=I0y5jU61pS4 ● “Driving Design through Examples” - Ciaran McNulty ○ https://www.youtube.com/watch?v=83GbyDpJDI4

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