Add interface (#15)

src/Service/VerificationService.php

@@ -28,7 +28,7 @@
 use Surfnet\YubikeyApiClient\Http\ServerPoolClient;
 use Surfnet\YubikeyApiClient\Otp;
 
-class VerificationService
+class VerificationService implements VerificationServiceInterface
 {
     /**
      * @var ServerPoolClient

src/Service/VerificationServiceInterface.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright 2024 SURFnet B.V.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Surfnet\YubikeyApiClient\Service;
+
+use Surfnet\YubikeyApiClient\Exception\RequestResponseMismatchException;
+use Surfnet\YubikeyApiClient\Exception\UntrustedSignatureException;
+use Surfnet\YubikeyApiClient\Otp;
+
+interface VerificationServiceInterface
+{
+}