#121 Magento2.Templates.HelperInTemplate Rule porposal

Magento2/Sniffs/Templates/ThisInTemplateSniff.md

@@ -14,6 +14,10 @@ Replace `$this` with `$block`. If you use private or protected methods, make the
 
 ---
 
+# Rule: Do not use `helpers` in templates
+## Background
+The use of helpers is in general discouraged. For template files, consider using a ViewModel instead.
+
 ## Reasoning
 The use of helpers is in general discouraged therefore any `$this->helper(<helper_class>)` code used in PHTML templates should be refactored.
 
@@ -23,7 +27,7 @@ Consider using ViewModel instead.
 
 Typical example of a helper being used in a PHTML:
 ```html
-<?php $_incl = $block->helper(<helper_class>)->...; ?>
+<?php $_incl = $this->helper(<helper_class>)->...; ?>
 ```
 
 Once the ViewModel is created, call it in the PHTML as follow:

Magento2/Sniffs/Templates/ThisInTemplateSniff.php

@@ -13,19 +13,33 @@
  */
 class ThisInTemplateSniff implements Sniff
 {
+    /**
+     * Warning violation code.
+     *
+     * @var string
+     */
+    protected $warningCodeFoundHelper = 'FoundHelper';
+
     /**
      * String representation of warning.
      *
      * @var string
      */
-    protected $warningMessage = 'Usage of $this in template files is deprecated.';
+    protected $warningMessageFoundHelper = 'The use of helpers in templates is discouraged. Use ViewModel instead.';
 
     /**
      * Warning violation code.
      *
      * @var string
      */
-    protected $warningCode = 'FoundThis';
+    protected $warningCodeFoundThis = 'FoundThis';
+
+    /**
+     * String representation of warning.
+     *
+     * @var string
+     */
+    protected $warningMessageFoundThis = 'The use of $this in templates is deprecated. Use $block instead.';
 
     /**
      * @inheritdoc
@@ -42,7 +56,12 @@ public function process(File $phpcsFile, $stackPtr)
     {
         $tokens = $phpcsFile->getTokens();
         if ($tokens[$stackPtr]['content'] === '$this') {
-            $phpcsFile->addWarning($this->warningMessage, $stackPtr, $this->warningCode);
+            $position = $phpcsFile->findNext(T_STRING, $stackPtr, null, false, 'helper', true);
+            if ($position !== false) {
+                $phpcsFile->addWarning($this->warningMessageFoundHelper, $position, $this->warningCodeFoundHelper);
+            } else {
+                $phpcsFile->addWarning($this->warningMessageFoundThis, $stackPtr, $this->warningCodeFoundThis);
+            }
         }
     }
 }