Updated http methods client mocking

Author: GrahamCampbell

test/Gitlab/Tests/ResultPagerTest.php

@@ -9,6 +9,7 @@
 use GuzzleHttp\Psr7\Response;
 use function GuzzleHttp\Psr7\stream_for;
 use Http\Client\Common\HttpMethodsClient;
+use Http\Client\Common\HttpMethodsClientInterface;
 use PHPUnit\Framework\TestCase;
 
 class ResultPagerTest extends TestCase
@@ -70,10 +71,14 @@ public function testFetchAll()
             ))
         ;
 
-        $httpClient = $this->getMockBuilder(HttpMethodsClient::class)
-            ->disableOriginalConstructor()
-            ->getMock()
-        ;
+        if (interface_exists(HttpMethodsClientInterface::class)) {
+            $httpClient = $this->createMock(HttpMethodsClientInterface::class);
+        } else {
+            $httpClient = $this->getMockBuilder(HttpMethodsClient::class)
+                ->disableOriginalConstructor()
+                ->getMock()
+            ;
+        }
 
         $httpClient->expects($this->exactly(2))
             ->method('get')