Added tests for elastic-api-version and compatibility mode

Author: ezimuel

tests/ClientTest.php

@@ -19,7 +19,6 @@
 use Elastic\Elasticsearch\Exception\ClientResponseException;
 use Elastic\Elasticsearch\Exception\ServerResponseException;
 use Elastic\Elasticsearch\Response\Elasticsearch;
-use Elastic\Transport\NodePool\NodePoolInterface;
 use Elastic\Transport\Transport;
 use Elastic\Transport\TransportBuilder;
 use Http\Mock\Client as MockClient;

tests/Traits/EndpointTraitTest.php

@@ -15,13 +15,20 @@
 namespace Elastic\Elasticsearch\Tests\Traits;
 
 use Elastic\Elasticsearch\Client;
+use Elastic\Elasticsearch\ClientInterface;
 use Elastic\Elasticsearch\Exception\ContentTypeException;
 use Elastic\Elasticsearch\Exception\MissingParameterException;
 use Elastic\Elasticsearch\Traits\EndpointTrait;
+use Elastic\Transport\TransportBuilder;
+use Http\Mock\Client as MockClient;
 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
 
 class EndpointTraitTest extends TestCase
 {
+    protected ClientInterface $client;
+
     use EndpointTrait;
 
     public static function getQueryStrings(): array
@@ -153,4 +160,42 @@ public function testCheckRequiredParameters(array $required, array $params, bool
             $this->checkRequiredParameters($required, $params);
         }
     }
+
+    public function testCreateRequestContainsApiVersionIfServerlessTrue()
+    {
+        $logger = new NullLogger();
+        $httpClient = new MockClient();
+
+        $transport = TransportBuilder::create()
+            ->setClient($httpClient)
+            ->build();
+
+        $this->client = new Client($transport, $logger);
+        $this->client->setServerless(true);
+
+        $request = $this->createRequest('GET', 'localhost:9200', []);
+
+        $this->assertEquals(Client::API_VERSION, $request->getHeader(Client::API_VERSION_HEADER)[0]);
+    }
+
+    public function testCreateRequestContainsCompatibilityModeIfServerlessFalse()
+    {
+        $logger = new NullLogger();
+        $httpClient = new MockClient();
+
+        $transport = TransportBuilder::create()
+            ->setClient($httpClient)
+            ->build();
+
+        $this->client = new Client($transport, $logger);
+        $this->client->setServerless(false);
+
+        $request = $this->createRequest('GET', 'localhost:9200', [
+            'Content-Type' => 'application/json',
+            'Accept' => 'application/json'
+        ]);
+
+        $this->assertEquals(sprintf(Client::API_COMPATIBILITY_HEADER, 'application', 'json'), $request->getHeader('Content-Type')[0]);
+        $this->assertEquals(sprintf(Client::API_COMPATIBILITY_HEADER, 'application', 'json'), $request->getHeader('Accept')[0]);
+    }
 }