Added frankfurter.dev provider

src/Service/Frankfurter.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+
+namespace Exchanger\Service;
+
+use Exchanger\Contract\ExchangeRate;
+use Exchanger\Contract\ExchangeRateQuery;
+use Exchanger\Contract\HistoricalExchangeRateQuery as HistoricalExchangeRateQueryContract;
+use Exchanger\Exception\UnsupportedCurrencyPairException;
+
+/**
+ * Uses the free API at https://frankfurter.dev/
+ */
+final class Frankfurter extends HttpService
+{
+    private const BASE_URL = "https://api.frankfurter.dev/v2/rates";
+
+    #[\Override]
+    public function supportQuery(ExchangeRateQuery $exchangeQuery): bool
+    {
+        return true;
+    }
+
+    #[\Override]
+    public function getName(): string
+    {
+        return 'frankfurter';
+    }
+
+    #[\Override]
+    public function getExchangeRate(ExchangeRateQuery $exchangeQuery): ExchangeRate
+    {
+        $currencyPair = $exchangeQuery->getCurrencyPair();
+        $base = $currencyPair->getBaseCurrency();
+        $quote = $currencyPair->getQuoteCurrency();
+
+        $url = self::BASE_URL . "?base={$base}&quotes={$quote}";
+
+        if ($exchangeQuery instanceof HistoricalExchangeRateQueryContract) {
+            $url .= '&date=' . $exchangeQuery->getDate()->format('Y-m-d');
+        }
+
+        $content = $this->request($url);
+        $data = json_decode($content, true);
+
+        if (!isset($data[0]['rate'])) {
+            throw new UnsupportedCurrencyPairException($currencyPair, $this);
+        }
+
+        $rate = (float)$data[0]['rate'];
+        $date = new \DateTime($data[0]['date']);
+
+        return $this->createRate($currencyPair, $rate, $date);
+    }
+}

src/Service/Registry.php

@@ -60,6 +60,7 @@ public static function getServices(): array
             'apilayer_currency_data' => ApiLayer\CurrencyData::class,
             'apilayer_exchange_rates_data' => ApiLayer\ExchangeRatesData::class,
             'unirate_api' => UniRateApi::class,
+            'frankfurter' => Frankfurter::class,
         ];
     }
 }

tests/Fixtures/Service/Frankfurter/EUR_USD.json

@@ -0,0 +1,8 @@
+[
+    {
+        "date": "2025-09-05",
+        "base": "EUR",
+        "quote": "USD",
+        "rate": 1.1697
+    }
+]

tests/Fixtures/Service/Frankfurter/EUR_USD_historic.json

@@ -0,0 +1,8 @@
+[
+    {
+        "date": "1999-04-13",
+        "base": "EUR",
+        "quote": "USD",
+        "rate": 1.0765
+    }
+]

tests/Fixtures/Service/Frankfurter/error_invalid_currency.json

@@ -0,0 +1,4 @@
+{
+    "status": 422,
+    "message": "invalid currency: ZZZ"
+}

tests/Tests/Service/FrankfurterTest.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Exchanger\Tests\Service;
+
+use Exchanger\CurrencyPair;
+use Exchanger\Exception\UnsupportedCurrencyPairException;
+use Exchanger\ExchangeRateQuery;
+use Exchanger\HistoricalExchangeRateQuery;
+use Exchanger\Service\Frankfurter;
+
+class FrankfurterTest extends ServiceTestCase
+{
+    public function testItHasAName(): void
+    {
+        $service = new Frankfurter($this->createMock('Http\Client\HttpClient'));
+
+        $this->assertSame('frankfurter', $service->getName());
+    }
+
+    public function testFetchLatestRate(): void
+    {
+        $url = 'https://api.frankfurter.dev/v2/rates?base=EUR&quotes=USD';
+        $content = file_get_contents(__DIR__.'/../../Fixtures/Service/Frankfurter/EUR_USD.json');
+
+        $pair = CurrencyPair::createFromString('EUR/USD');
+        $service = new Frankfurter($this->getHttpAdapterMock($url, $content));
+
+        $rate = $service->getExchangeRate(new ExchangeRateQuery($pair));
+
+        $this->assertSame(1.1697, $rate->getValue());
+        $this->assertEquals(new \DateTime('2025-09-05'), $rate->getDate());
+    }
+
+    public function testFetchHistoricRate(): void
+    {
+        $url = 'https://api.frankfurter.dev/v2/rates?base=EUR&quotes=USD&date=1999-04-13';
+        $content = file_get_contents(__DIR__.'/../../Fixtures/Service/Frankfurter/EUR_USD_historic.json');
+
+        $pair = CurrencyPair::createFromString('EUR/USD');
+        $service = new Frankfurter($this->getHttpAdapterMock($url, $content));
+
+        $rate = $service->getExchangeRate(new HistoricalExchangeRateQuery($pair, new \DateTime("1999-04-13")));
+
+        $this->assertSame(1.0765, $rate->getValue());
+        $this->assertEquals(new \DateTime('1999-04-13'), $rate->getDate());
+    }
+
+    public function testUnsupportedCurrencyPair(): void
+    {
+        $this->expectException(UnsupportedCurrencyPairException::class);
+
+        $url = 'https://api.frankfurter.dev/v2/rates?base=EUR&quotes=ZZZ';
+        $content = file_get_contents(__DIR__.'/../../Fixtures/Service/Frankfurter/error_invalid_currency.json');
+
+        $pair = CurrencyPair::createFromString('EUR/ZZZ');
+        $service = new Frankfurter($this->getHttpAdapterMock($url, $content, 422));
+
+        $service->getExchangeRate(new ExchangeRateQuery($pair));
+    }
+}