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AydinHassanAydinHassan
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Merge pull request #28 from php-school/stringify-to-demystify
Add stringify to demysitify exercise
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‎app/bootstrap.php‎

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use PhpSchool\PHP8Appreciate\Exercise\TheReturnOfStatic;
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use PhpSchool\PHP8Appreciate\Exercise\ThrowAnExpression;
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use PhpSchool\PHP8Appreciate\Exercise\UniteTheTypes;
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use PhpSchool\PHP8Appreciate\Exercise\StringifyToDemystify;
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use PhpSchool\PhpWorkshop\Application;
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$app = new Application('PHP8 Appreciate', __DIR__ . '/config.php');
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$app->addExercise(AllMixedUp::class);
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$app->addExercise(TheReturnOfStatic::class);
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$app->addExercise(ThrowAnExpression::class);
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$app->addExercise(StringifyToDemystify::class);
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$art = <<<ART
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_ __ _

‎app/config.php‎

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use PhpSchool\PHP8Appreciate\Exercise\TheReturnOfStatic;
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use PhpSchool\PHP8Appreciate\Exercise\ThrowAnExpression;
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use PhpSchool\PHP8Appreciate\Exercise\UniteTheTypes;
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use PhpSchool\PHP8Appreciate\Exercise\StringifyToDemystify;
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use Psr\Container\ContainerInterface;
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use function DI\create;
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},
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ThrowAnExpression::class => function (ContainerInterface $c) {
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return new ThrowAnExpression($c->get(PhpParser\Parser::class), $c->get(\Faker\Generator::class));
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}
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},
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StringifyToDemystify::class => function (ContainerInterface $c) {
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return new StringifyToDemystify($c->get(PhpParser\Parser::class));
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},
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];

‎exercises/stringify-to-demystify/problem/problem.md‎

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`__toString()` a magic class method long-standing in PHP but never truly something you could rely on unless you rolled your own interface. All that has changed with the simple introduction of the `Stringable` interface in PHP 8.
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`Stringable` is a simple interface that requires the implementation of `__toString(): string`
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----------------------------------------------------------------------
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Create a program that reads the JSON body of the request input stream (mimicking an API response). The body will need to be JSON decoded and will be a variation of the example below:
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```json
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{
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"success": false,
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"status": "401",
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"error": "Unauthorized: Not authorised for this resource"
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}
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```
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You will need to define a new class that implements `Stringable` and it's method requirements. This class should take enough information from the request so that the `__toString` method can return a string like below:
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```
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Status: 401
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Error: Unauthorized: Not authorised for this resource
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```
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Once constructed pass the object to a `log_failure` function. This function is provided for you and has a signature of `log_failure(\Stringable $error): void`.
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Your program may also receive successful payloads, which you should ignore for the purposes of this exercise. These requests will be identifiable by the `success` key in the decoded JSON payload.
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### The advantages of the new Stringable interface
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* Allows typing of string like objects
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* Can be used in conjunction with union types alongside `string`
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----------------------------------------------------------------------
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## HINTS
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To easily read the request body you can use `file_get_contents('php://input')`
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For more details look at the docs for...
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**Stringable** - [https://www.php.net/manual/en/class.stringable.php]()
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Note that while the `Stringable` interface isn't required to pass the type hint check, however, it should be used if not only to show intent.
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Oh, and don't forget about the basics for classes and interfaces :)
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**class** - [https://www.php.net/manual/en/language.oop5.basic.php]()
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**interfaces** - [https://www.php.net/manual/en/language.oop5.interfaces.php]()

‎exercises/stringify-to-demystify/solution/solution.php‎

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<?php
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class FailedResponse implements \Stringable {
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public function __construct(private string $status, private string $error)
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{
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}
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public function __toString()
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{
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return "Status: {$this->status} \nError: {$this->error}";
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}
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}
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$request = json_decode(file_get_contents('php://input'), true);
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if (!$request['success']) {
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log_failure(new FailedResponse($request['status'], $request['error']));
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}

‎src/Exercise/StringifyToDemystify.php‎

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<?php
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declare(strict_types=1);
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namespace PhpSchool\PHP8Appreciate\Exercise;
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use GuzzleHttp\Psr7\Request;
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use PhpParser\Node\Name;
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use PhpParser\Node\Stmt;
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use PhpParser\Node\Stmt\Class_;
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use PhpParser\Node\Stmt\TryCatch;
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use PhpParser\NodeFinder;
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use PhpParser\Parser;
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use PhpSchool\PhpWorkshop\Check\FunctionRequirementsCheck;
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use PhpSchool\PhpWorkshop\CodeInsertion;
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use PhpSchool\PhpWorkshop\Exercise\AbstractExercise;
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use PhpSchool\PhpWorkshop\Exercise\CgiExercise;
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use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
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use PhpSchool\PhpWorkshop\Exercise\ExerciseType;
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use PhpSchool\PhpWorkshop\Exercise\SubmissionPatchable;
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use PhpSchool\PhpWorkshop\ExerciseCheck\FunctionRequirementsExerciseCheck;
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use PhpSchool\PhpWorkshop\ExerciseCheck\SelfCheck;
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use PhpSchool\PhpWorkshop\ExerciseDispatcher;
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use PhpSchool\PhpWorkshop\Input\Input;
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use PhpSchool\PhpWorkshop\Patch;
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use PhpSchool\PhpWorkshop\Result\Failure;
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use PhpSchool\PhpWorkshop\Result\ResultInterface;
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use PhpSchool\PhpWorkshop\Result\Success;
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use Psr\Http\Message\RequestInterface;
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use Stringable;
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class StringifyToDemystify extends AbstractExercise implements
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ExerciseInterface,
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CgiExercise,
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SubmissionPatchable,
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FunctionRequirementsExerciseCheck,
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SelfCheck
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{
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public function __construct(private Parser $parser)
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{
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}
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public function getName(): string
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{
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return 'Stringify to Demystify';
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}
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public function getDescription(): string
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{
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return 'PHP 8\'s Stringable Interface';
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}
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public function getType(): ExerciseType
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{
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return ExerciseType::CGI();
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}
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public function configure(ExerciseDispatcher $dispatcher): void
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{
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$dispatcher->requireCheck(FunctionRequirementsCheck::class);
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}
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/**
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* @return array<RequestInterface>
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*/
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public function getRequests(): array
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{
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return array_map(
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fn () => new Request(
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'POST',
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'https://phpschool.io/api',
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[],
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json_encode($this->getRandRequest(), JSON_THROW_ON_ERROR)
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),
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array_fill(0, random_int(3, 6), null)
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);
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}
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/**
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* @return array{'success': bool, 'status': int, 'error'?: string, 'body'?: string}
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* @throws \Exception
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*/
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public function getRandRequest(): array
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{
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return [
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[
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'success' => true,
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'status' => 200,
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'body' => ['{fake: "data"}', '{stub: "payload"}'][random_int(0, 1)]
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],
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[
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'success' => false,
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'status' => 400,
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'error' => ['Bad Request: Incorrect mime type', 'Bad Request: Invalid key "id"'][random_int(0, 1)]
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],
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[
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'success' => false,
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'status' => 401,
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'error' => ['Unauthorized: Not authorised for this resource', 'Bad API token'][random_int(0, 1)]
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],
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[
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'success' => false,
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'status' => 403,
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'error' => ['Forbidden: Access forbidden', 'Forbidden: ACL not granted for resource'][random_int(0, 1)]
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],
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[
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'success' => false,
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'status' => 500,
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'error' => ['Server Error: Contact webmaster', 'Server Error: err_code: 3289327'][random_int(0, 1)]
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],
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][random_int(0, 4)];
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}
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public function getPatch(): Patch
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{
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$code = <<<CODE
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function log_failure(\Stringable \$error) {
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echo \$error;
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}
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CODE;
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return (new Patch())->withInsertion(new CodeInsertion(CodeInsertion::TYPE_BEFORE, $code));
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}
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public function getRequiredFunctions(): array
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{
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return ['log_failure'];
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}
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public function getBannedFunctions(): array
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{
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return [];
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}
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public function check(Input $input): ResultInterface
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{
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/** @var Stmt[] $statements */
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$statements = $this->parser->parse((string) file_get_contents($input->getRequiredArgument('program')));
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/** @var Class_|null $classStmt */
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$classStmt = (new NodeFinder())->findFirstInstanceOf($statements, Class_::class);
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if (!$classStmt) {
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return new Failure($this->getName(), 'No class statement could be found');
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}
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$implements = array_filter($classStmt->implements, fn (Name $name) => $name->toString() === Stringable::class);
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if (empty($implements)) {
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return new Failure($this->getName(), 'Your class should implement the Stringable interface');
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}
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return new Success($this->getName());
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}
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}

‎test/Exercise/StringifyToDemystifyTest.php‎

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<?php
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declare(strict_types=1);
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namespace PhpSchool\PHP8AppreciateTest\Exercise;
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use PhpSchool\PHP8Appreciate\Exercise\StringifyToDemystify;
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use PhpSchool\PhpWorkshop\Application;
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use PhpSchool\PhpWorkshop\Result\Failure;
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use PhpSchool\PhpWorkshop\Result\FunctionRequirementsFailure;
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use PhpSchool\PhpWorkshop\TestUtils\WorkshopExerciseTest;
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class StringifyToDemystifyTest extends WorkshopExerciseTest
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{
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public function getExerciseClass(): string
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{
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return StringifyToDemystify::class;
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}
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public function getApplication(): Application
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{
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return require __DIR__ . '/../../app/bootstrap.php';
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}
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public function testWithNoClass(): void
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{
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$this->runExercise('solution-no-class.php');
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$this->assertVerifyWasNotSuccessful();
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$this->assertResultsHasFailureAndMatches(
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FunctionRequirementsFailure::class,
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function (FunctionRequirementsFailure $failure) {
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self::assertSame(['log_failure'], $failure->getMissingFunctions());
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return true;
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}
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);
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}
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public function testWithNotImplementingStringable(): void
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{
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$this->runExercise('solution-no-stringable.php');
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$this->assertVerifyWasNotSuccessful();
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$this->assertResultsHasFailure(Failure::class, 'Your class should implement the Stringable interface');
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}
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public function testSolution(): void
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{
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$this->runExercise('solution.php');
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$this->assertVerifyWasSuccessful();
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}
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}

‎test/solutions/stringify-to-demystify/solution-no-class.php‎

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<?php
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$request = json_decode(file_get_contents('php://input'), true);
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if (!$request['success']) {
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echo "Status: {$request['status']} \nError: {$request['error']}";
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}

‎test/solutions/stringify-to-demystify/solution-no-stringable.php‎

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<?php
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class FailedResponse {
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public function __construct(private string $status, private string $error)
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{
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}
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public function __toString()
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{
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return "Status: {$this->status} \nError: {$this->error}";
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}
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}
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$request = json_decode(file_get_contents('php://input'), true);
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if (!$request['success']) {
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log_failure(new FailedResponse($request['status'], $request['error']));
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}

‎test/solutions/stringify-to-demystify/solution.php‎

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<?php
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class FailedResponse implements \Stringable {
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public function __construct(private string $status, private string $error)
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{
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}
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public function __toString()
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{
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return "Status: {$this->status} \nError: {$this->error}";
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}
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}
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$request = json_decode(file_get_contents('php://input'), true);
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if (!$request['success']) {
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log_failure(new FailedResponse($request['status'], $request['error']));
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}

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