Level 3.B ~30 min Target: PHPStan max

Boss: take it to max

This returns service passes PHPStan at max. On paper it's finished. Then you read phpstan.neon:

a baseline of eight entries, one of which no longer matches anything
reportUnmatchedIgnoredErrors: false, added the day a fix turned the build red, so nobody has heard about a fixed error since
no strict rules

Meanwhile, an unknown order number crashes the returns page, "7" is accepted as an order ID until it reaches a typed return, and SKU 0100 is refused as a final sale item because SKU 100 is one.

A green build is only as honest as its configuration. Your job is to make this one honest.

Your checklist

Level	Ask of the project
3.1 Living with a baseline	Does every baseline entry hide a real error? Is PHPStan allowed to say when one doesn't? Can you get it to zero?
3.2 `mixed`, the final enemy	Is the request checked once, where the JSON arrives, so nothing after it sees `mixed`?
3.3 Extensions	Is anything in `phpstan.neon` hiding errors instead of explaining them?
3.4 Strict rules	With strict rules on, is every comparison strict and every condition a boolean?
3.5 Custom rules	Is there a convention here worth a rule? Not for this exercise, but worth asking of your own project.

Start by removing reportUnmatchedIgnoredErrors and running Analyse to find the stale entry. When the baseline is empty, leave the file with ignoreErrors: [] and add strict rules to includes. The tests check the behaviour and the configuration.

CHALLENGE

The returns service is green at level max, but only because of its configuration. Its baseline hides two bugs, one entry no longer matches anything, and the check that would say so is switched off.

Make it honestly clean: no baseline entries, unmatched ignores reported, and strict rules on. Fix ReturnRequest and ReturnPolicy as you go:

ReturnRequest::fromJson() checks the JSON once, and throws an UnexpectedValueException for a bad request. reason() returns a ReturnReason, and a missing or unknown reason counts as ChangedMind
ReturnPolicy refuses an unknown order with ReturnRefused::unknownOrder(), and compares SKUs exactly

REFERENCE

An empty baseline, as --generate-baseline --allow-empty-baseline writes it:

parameters:
    ignoreErrors: []

Strict rules are installed, and a project includes them like this:

includes:
    - vendor/phpstan/phpstan-strict-rules/rules.neon

<?php

declare(strict_types=1);

final readonly class Order
{
    /** @param list<string> $skus */
    public function __construct(public int $id, public DateTimeImmutable $deliveredAt, public array $skus) {}
}

<?php

declare(strict_types=1);

final class Orders
{
    /** @var array<int, Order> */
    private array $byId = [];

    public function __construct(Order ...$orders)
    {
        foreach ($orders as $order) {
            $this->byId[$order->id] = $order;
        }
    }

    public function find(int $id): ?Order
    {
        return $this->byId[$id] ?? null;
    }
}

<?php

declare(strict_types=1);

enum ReturnReason: string
{
    case Faulty = 'faulty';
    case WrongSize = 'wrong_size';
    case ChangedMind = 'changed_mind';
}

<?php

declare(strict_types=1);

final class ReturnRefused extends DomainException
{
    public static function unknownOrder(int $id): self
    {
        return new self("There's no order {$id}");
    }

    public static function notInOrder(string $sku): self
    {
        return new self("{$sku} isn't in this order");
    }

    public static function finalSale(string $sku): self
    {
        return new self("{$sku} was a final sale item");
    }

    public static function tooLate(DateTimeImmutable $deadline): self
    {
        return new self('Returns for this order closed on ' . $deadline->format('j F Y'));
    }
}

Running on PHP 8.3…

Run the tests, run PHPStan, or submit for both. Ctrl/⌘ + Enter submits from the editor.