Created API tests for errors when resolving short URLs

module/Rest/test-api/Action/ResolveShortUrlActionTest.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ShlinkioApiTest\Shlink\Rest\Action;
+
+use Shlinkio\Shlink\Rest\Util\RestUtils;
+use Shlinkio\Shlink\TestUtils\ApiTest\ApiTestCase;
+
+class ResolveShortUrlActionTest extends ApiTestCase
+{
+    /** @test */
+    public function tryingToResolveInvalidUrlReturnsNotFoundError(): void
+    {
+        $resp = $this->callApiWithKey(self::METHOD_GET, '/short-urls/invalid');
+        ['error' => $error] = $this->getJsonResponsePayload($resp);
+
+        $this->assertEquals(self::STATUS_NOT_FOUND, $resp->getStatusCode());
+        $this->assertEquals(RestUtils::INVALID_ARGUMENT_ERROR, $error);
+    }
+}