Best practices for crafting high quality PHP apps - PHP UK 2019

@asgrim Best practices for crafting high quality PHP apps James Titcumb PHP UK 2019 Please clone & composer install: https://github.com/asgrim/quality-tutorial WiFi: phpukconference / community

$ whoami James Titcumb www.jamestitcumb.com www.roave.com @asgrim Please clone & composer install: https://github.com/asgrim/quality-tutorial WiFi: phpukconference / community

@asgrim Please clone & composer install: https://github.com/asgrim/quality-tutorial WiFi: phpukconference / community

@asgrim What is “quality”?

@asgrim photo: Rob Allen https://flic.kr/p/qmGpsq

@asgrim "The best code is no code at all” -- Jeff Atwood source: https://blog.codinghorror.com/the-best-code-is-no-code-at-all/

@asgrim Prototyping & short-lived apps/sites

@asgrim Products Long-lived projects. Open source software.

@asgrim What is quality in applications?

@asgrim What about time/cost…?

@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/

@asgrim This talk... ● Planning ● Development ● Testing ● Continuous integration ● Code reviews ● Deployments

@asgrim Planning is communication

@asgrim Use business terminology

@asgrim Build a model of the business

@asgrim The model must be fluid.

@asgrim “There are only two hard things in Computer Science: cache invalidation and naming things.” -- Phil Karlton source: https://martinfowler.com/bliki/TwoHardThings.html

@asgrim SimpleBeanFactoryAwareAspectInstanceFactory

@asgrim “Give awkward names to awkward concepts” -- Eric Evans source: https://skillsmatter.com/conferences/8231-ddd-exchange-2017

@asgrim Avoid early abstraction

@asgrim “Code for your use-case, not for your re-use-case” -- Marco Pivetta source: https://ocramius.github.io/extremely-defensive-php/#/39

@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

@asgrim Strict type declarations. Use declare(strict_types=1); by default

@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; } }

@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));

@asgrim Testing is NOT a separate line item

@asgrim Testing should be an assumption

@asgrim You’re already testing.

@asgrim Still need convincing?

@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

@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

@asgrim More complexity = more tests

@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);

@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);

@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!!!

@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!!!

@asgrim Prevent coverage leaking

@asgrim Prevent coverage leaking <?php namespace Foo; /** * @covers FooBar */ final class BarTest extends TestCase { // write some tests! }

@asgrim Are the tests testing?

@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

@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

@asgrim Test the tests are testing!

@asgrim Mutation testing function add(int $a, int $b) : int { return $a + $b; } function testAdd() { $result = add(2, 3); // self::assertSame(5, $result); }

@asgrim Mutation testing function add(int $a, int $b) : int { return $a - $b; } function testAdd() { $result = add(2, 3); // self::assertSame(5, $result); }

@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 }

@asgrim What about other tests?

@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

@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

@asgrim Why is this important?

@asgrim Automated tests Application (and UI, API, etc.) Domain / Business Logic Infrastructure (DBAL, APIs, etc.)

@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); }

@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

@asgrim Automate all the things!

@asgrim Continuous Integration

@asgrim Tests cost money to run (manually)

@asgrim What to look for in code review?

@asgrim What to look for in code review? Code style.

@asgrim What to look for in code review? Small, atomic changes.

@asgrim What to look for in code review? Composer versions.

@asgrim What to look for in code review? Structure & good practices.

@asgrim What to look for in code review? Tests.

@asgrim What to look for in code review? Documentation.

@asgrim What to look for in code review? Security.

@asgrim What to look for in code review? Insight.

@asgrim “Move fast and break things” -- a stupid Facebook mantra

@asgrim “Move fast and break things with stable infra” -- Facebook mantra since 2014

@asgrim Continuous Delivery & Deployment

@asgrim Better quality = Higher confidence

@asgrim Better quality = Higher confidence = Happy customers

Any questions? James Titcumb @asgrim

@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 ● Object Calisthenics - William Durand ○ https://williamdurand.fr/2013/06/03/object-calisthenics/ ● “Driving Design through Examples” - Ciaran McNulty ○ https://www.youtube.com/watch?v=83GbyDpJDI4 ● Code Review Checklist ○ https://github.com/asgrim/code-review-checklist/blob/master/index.md

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