Best practices for crafting high quality PHP apps (PHP South Africa 2018)

@asgrim
Best practices for crafting high
quality PHP apps
James Titcumb
PHP South Africa 2018
Please clone & composer install:
https://github.com/asgrim/quality-tutorial

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

@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

@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
if ($a) {
echo "A";
}
if ($b) {
echo "B";
}
}
foo(true, false);
foo(false, true);

@asgrim
Branch coverage
<?php
if ($a) {
echo "A";
}
if ($b) {
echo "B";
}
}
foo(true, false);
foo(false, true);
foo(false, false); // NEW TEST!!!

@asgrim
Branch coverage
<?php
if ($a) {
echo "A";
}
if ($b) {
echo "B";
}
}
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
return $a - $b;
}
// self::assertSame(5, $result);
}

@asgrim
Mutation testing
return $a - $b;
}
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
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...
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!!!
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
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
Code style.

@asgrim
Small, atomic changes.

@asgrim
Composer versions.

@asgrim
Structure & good practices.

@asgrim
Tests.

@asgrim
Documentation.

@asgrim
Security.

@asgrim
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

Best practices for crafting high quality PHP apps (PHP South Africa 2018)

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à Best practices for crafting high quality PHP apps (PHP South Africa 2018)

Similaire à Best practices for crafting high quality PHP apps (PHP South Africa 2018) (20)

Plus de James Titcumb

Plus de James Titcumb (18)

Dernier

Dernier (20)

Best practices for crafting high quality PHP apps (PHP South Africa 2018)