Money validator

.github/workflows/test.yml

@@ -0,0 +1,42 @@
+name: Run Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.2
+          extensions: mysqli
+
+      - name: Install Composer dependencies
+        working-directory: ./code
+        run: composer install --prefer-dist --no-progress
+
+      - name: Copy .env.example to .env
+        working-directory: ./code
+        run: cp .env.example .env
+
+      - name: Generate app key
+        working-directory: ./code
+        run: php artisan key:generate
+
+      - name: Run database migrations
+        working-directory: ./code
+        run: php artisan migrate
+
+      - name: Run tests
+        working-directory: ./code
+        run: vendor/bin/phpunit

code/app/DTO/Request.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\DTO;
+
+use Money\Currency;
+use Money\Money;
+
+final readonly class Request
+{
+    private function __construct(private Money $amount)
+    {
+    }
+
+    public static function create(int $amountInCents, string $currency): self
+    {
+        return new self(new Money($amountInCents, new Currency(strtoupper($currency))));
+    }
+
+    public function getAmount(): Money
+    {
+        return $this->amount;
+    }
+
+    public function getCurrency(): string
+    {
+        return $this->amount->getCurrency()->getCode();
+    }
+}

code/app/DTO/Transaction.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\DTO;
+
+use Money\Currency;
+use Money\Money;
+
+final readonly class Transaction
+{
+    private function __construct(private Money $amount)
+    {
+    }
+
+    public static function create(int $amountInCents, string $currency): self
+    {
+        return new self(new Money($amountInCents, new Currency(strtoupper($currency))));
+    }
+
+    public function getAmount(): Money
+    {
+        return $this->amount;
+    }
+
+    public function getCurrency(): string
+    {
+        return $this->amount->getCurrency()->getCode();
+    }
+}

code/app/Http/Controllers/TransactionController.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use App\Services\RequestMoneyValidator;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Routing\Controller;
+use InvalidArgumentException;
+
+final class TransactionController extends Controller
+{
+    public function __construct(private readonly RequestMoneyValidator $validator)
+    {
+    }
+
+    public function validateTransaction(): JsonResponse
+    {
+        try {
+            $userRequest = Request::create(10000, 'USD');
+            $transaction = Transaction::create(9000, 'USD');
+
+            $isValid = $this->validator->validate($userRequest, $transaction);
+
+            return response()->json(['isValid' => $isValid]);
+        } catch (InvalidArgumentException $e) {
+            return response()->json([
+                'error' => 'Validation failed',
+                'message' => $e->getMessage()
+            ], 400);
+        }
+    }
+}

code/app/Providers/AppServiceProvider.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Providers;
+
+use App\Services\RequestMoneyValidator;
+use Illuminate\Support\ServiceProvider;
+
+class AppServiceProvider extends ServiceProvider
+{
+    /**
+     * Register any application services.
+     */
+    public function register(): void
+    {
+        $this->app->singleton(RequestMoneyValidator::class, function ($app) {
+            return new RequestMoneyValidator(
+                deviation: config('app.transaction_deviation')
+            );
+        });
+    }
+
+    /**
+     * Bootstrap any application services.
+     */
+    public function boot(): void
+    {
+        //
+    }
+}

code/app/Services/RequestMoneyValidator.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Services;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use InvalidArgumentException;
+
+final readonly class RequestMoneyValidator
+{
+    public function __construct(private int $deviation)
+    {
+    }
+
+    public function validate(Request $request, Transaction $transaction): bool
+    {
+        if (!filter_var(
+            $this->deviation,
+            FILTER_VALIDATE_INT,
+            ['options' => ['min_range' => 0, 'max_range' => 100]]
+        )) {
+            throw new InvalidArgumentException('Deviation must be between 0 and 100.');
+        }
+
+        if ($request->getCurrency() !== $transaction->getCurrency()) {
+            return false;
+        }
+
+        $deviationPercentage = (string) ($this->deviation / 100);
+        $deviationAmount = $transaction->getAmount()->multiply($deviationPercentage);
+
+        $minAmount = $transaction->getAmount()->subtract($deviationAmount);
+        $maxAmount = $transaction->getAmount()->add($deviationAmount);
+
+        return $request->getAmount()->greaterThanOrEqual($minAmount)
+            && $request->getAmount()->lessThanOrEqual($maxAmount);
+    }
+}

code/config/app.php

@@ -123,5 +123,5 @@
         'store' => env('APP_MAINTENANCE_STORE', 'database'),
     ],
 
-    'transaction_deviation' => env('TRANSACTION_DEVIATION', 5),
+    'transaction_deviation' => (int) env('TRANSACTION_DEVIATION', 5),
 ];

code/routes/web.php

@@ -0,0 +1,10 @@
+<?php
+
+use App\Http\Controllers\TransactionController;
+use Illuminate\Support\Facades\Route;
+
+Route::get('/', function () {
+    return view('welcome');
+});
+
+Route::get('/validate-transaction', [TransactionController::class, 'validateTransaction']);

code/tests/Feature/TransactionControllerTest.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Feature;
+
+use Tests\TestCase;
+
+class TransactionControllerTest extends TestCase
+{
+    public function test_validate_transaction_success(): void
+    {
+        $response = $this->getJson('/validate-transaction');
+
+        $response->assertStatus(200)
+            ->assertJson(['isValid' => false]);
+    }
+
+    public function test_validate_transaction_invalid_deviation(): void
+    {
+        config(['app.transaction_deviation' => 150]);
+
+        $response = $this->getJson('/validate-transaction');
+
+        $response->assertStatus(400)
+            ->assertJson([
+                'error' => 'Validation failed',
+                'message' => 'Deviation must be between 0 and 100.'
+            ]);
+    }
+}

code/tests/Unit/RequestMoneyValidatorTest.php

@@ -0,0 +1,74 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use App\Services\RequestMoneyValidator;
+use InvalidArgumentException;
+use Tests\TestCase;
+
+class RequestMoneyValidatorTest extends TestCase
+{
+    public function test_validate_currency_mismatch(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(10000, 'EUR');
+        $validator = new RequestMoneyValidator(10);
+
+        $this->assertFalse($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_within_deviation(): void
+    {
+        $request = Request::create(9500, 'USD');
+        $transaction = Transaction::create(9000, 'USD');
+
+        $validator = new RequestMoneyValidator(10);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_outside_deviation(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(9000, 'USD');
+
+        $validator = new RequestMoneyValidator(5);
+
+        $this->assertFalse($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_exact_amount(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(10000, 'USD');
+        $validator = new RequestMoneyValidator(10);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_small_deviation(): void
+    {
+        $request = Request::create(9950, 'USD');
+        $transaction = Transaction::create(10000, 'USD');
+
+        $validator = new RequestMoneyValidator(1);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_negative_deviation_throws_exception(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Deviation must be between 0 and 100.');
+
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(9000, 'USD');
+        $validator = new RequestMoneyValidator(-5);
+
+        $validator->validate($request, $transaction);
+    }
+}