Made test properties to be private instead of protected

module/Rest/test/Middleware/AuthenticationMiddlewareTest.php

@@ -32,12 +32,12 @@ use function Zend\Stratigility\middleware;
 class AuthenticationMiddlewareTest extends TestCase
 {
     /** @var AuthenticationMiddleware */
-    protected $middleware;
+    private $middleware;
     /** @var ObjectProphecy */
-    protected $requestToPlugin;
+    private $requestToPlugin;
 
     /** @var callable */
-    protected $dummyMiddleware;
+    private $dummyMiddleware;
 
     public function setUp()
     {

module/Rest/test/Middleware/CrossDomainMiddlewareTest.php

@@ -14,9 +14,9 @@ use Zend\Diactoros\ServerRequestFactory;
 class CrossDomainMiddlewareTest extends TestCase
 {
     /** @var CrossDomainMiddleware */
-    protected $middleware;
+    private $middleware;
     /** @var ObjectProphecy */
-    protected $delegate;
+    private $delegate;
 
     public function setUp()
     {

module/Rest/test/Middleware/PathVersionMiddlewareTest.php

@@ -17,7 +17,7 @@ use function array_shift;
 class PathVersionMiddlewareTest extends TestCase
 {
     /** @var PathVersionMiddleware */
-    protected $middleware;
+    private $middleware;
 
     public function setUp()
     {