MDL-76474 tiny_accessibilitychecker: Prevent placeholders to be assessed

lib/editor/tiny/plugins/accessibilitychecker/amd/src/checker.js

@@ -25,6 +25,7 @@ import {component} from './common';
 import * as Modal from 'core/modal_factory';
 import * as ModalEvents from 'core/modal_events';
 import ColorBase from './colorbase';
+import {getPlaceholderSelectors} from 'editor_tiny/options';
 
 /**
  * @typedef ProblemDetail
@@ -48,6 +49,11 @@ export default class {
         this.editor = editor;
         this.colorBase = new ColorBase();
         this.modal = null;
+        this.placeholderSelectors = null;
+        const placeholders = getPlaceholderSelectors(this.editor);
+        if (placeholders.length) {
+            this.placeholderSelectors = placeholders.join(', ');
+        }
     }
 
     destroy() {
@@ -247,7 +253,14 @@ export default class {
             nodeData: [],
         };
 
-        warning.nodeData = [...nodes].map((node) => {
+        warning.nodeData = [...nodes].filter((node) => {
+            // If the failed node is a placeholder element. We should remove it from the list.
+            if (node !== this.editor && this.placeholderSelectors) {
+                return node.matches(this.placeholderSelectors) === false;
+            }
+
+            return node;
+        }).map((node) => {
             const describedNode = getEventualNode(node);
 
             // Find the index of the node within the type of node.

lib/editor/tiny/plugins/accessibilitychecker/tests/behat/accessibilitychecker.feature

@@ -1,4 +1,4 @@
-@editor @editor_tiny
+@editor @editor_tiny @tiny_accessibilitychecker
 Feature: Tiny editor accessibility checker
   To write accessible content in Tiny, I need to check for accessibility warnings.
 
@@ -43,3 +43,11 @@ Feature: Tiny editor accessibility checker
     When I press "Save image"
     And I click on the "Tools > Accessibility checker" menu item for the "Description" TinyMCE editor
     Then I should see "Congratulations, no accessibility issues found!" in the "Accessibility checker" "dialogue"
+
+  @javascript
+  Scenario: Placeholder element will not be assessed by accessibility checker
+    Given I log in as "admin"
+    And I open my profile in edit mode
+    When I set the field "Description" to "<p>Some plain text</p><img src='/broken-image' width='1' height='1' class='behat-tinymce-placeholder'/><p>Some more text</p>"
+    And I click on the "Tools > Accessibility checker" menu item for the "Description" TinyMCE editor
+    Then I should see "Congratulations, no accessibility issues found!" in the "Accessibility checker" "dialogue"

lib/editor/tiny/plugins/accessibilitychecker/upgrade.txt

@@ -0,0 +1,7 @@
+This files describes API changes in tiny_accessibilitychecker - TinyMCE Accessibility checker plugin,
+information provided here is intended especially for developers.
+
+=== 4.2 ===
+
+* The placeholder elements which were registered in placeholderSelectors in editor_tiny/options will not be
+  assessed by the accessibility checker plugin.