Move deprecations into constructors.

src/View/Helper/RssHelper.php

@@ -14,10 +14,9 @@
  */
 namespace Cake\View\Helper;
 
-deprecationWarning('RssHelper is deprecated and will be removed in 4.0.0');
-
 use Cake\Utility\Xml;
 use Cake\View\Helper;
+use Cake\View\View;
 
 /**
  * RSS Helper class for easy output RSS structures.
@@ -94,6 +93,15 @@ class RssHelper extends Helper
     public $version = '2.0';
 
     /**
+     * {@inheritDoc}
+     */
+    public function __construct(View $view, array $settings = [])
+    {
+        deprecationWarning('RssHelper is deprecated and will be removed in 4.0.0');
+        parent::__construct($view, $settings);
+    }
+
+    /**
      * Returns an RSS document wrapped in `<rss />` tags
      *
      * @param array $attrib `<rss />` tag attributes

src/View/Helper/SessionHelper.php

@@ -14,11 +14,6 @@
  */
 namespace Cake\View\Helper;
 
-deprecationWarning(
-    'SessionHelper is deprecated and will be removed in 4.0.0. ' .
-    'Use request->session() instead.'
-);
-
 use Cake\View\Helper;
 use Cake\View\View;
 
@@ -41,7 +36,11 @@ class SessionHelper extends Helper
      */
     public function __construct(View $View, array $config = [])
     {
-        trigger_error('SessionHelper has been deprecated. Use request->session() instead.', E_USER_DEPRECATED);
+        deprecationWarning(
+            'SessionHelper is deprecated and will be removed in 4.0.0. ' .
+            'Use request->session() instead.'
+        );
+
         parent::__construct($View, $config);
     }
 

tests/TestCase/View/Helper/RssHelperTest.php

@@ -24,6 +24,8 @@ use Cake\View\View;
 
 /**
  * RssHelperTest class
+ *
+ * @group deprecated
  */
 class RssHelperTest extends TestCase
 {
@@ -42,13 +44,12 @@ class RssHelperTest extends TestCase
     {
         parent::setUp();
 
-        $errorLevel = error_reporting();
-        error_reporting(E_ALL ^ E_USER_DEPRECATED);
+        $oldLevel = error_reporting(E_ALL ^ E_USER_DEPRECATED);
 
         $this->View = new View();
         $this->Rss = new RssHelper($this->View);
 
-        error_reporting($errorLevel);
+        error_reporting($oldLevel);
     }
 
     /**