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 talk, we’ll take a quick look into each of these areas, looking at how we can make positive, actionable change in our workflow.
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/
30. @asgrim
“There are only two hard things in Computer
Science: cache invalidation and naming things.”
-- Phil Karlton
source: https://martinfowler.com/bliki/TwoHardThings.html
43. @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;
}
}
44. @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));
50. @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
51. @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
63. @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
68. @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. @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
73. @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-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
78. @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);
}
79. @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