fix(no-restricted-class): error in empty value (#2425)

Author: waynzh

Diff for: lib/rules/no-restricted-class.js

@@ -132,7 +132,7 @@ module.exports = {
       /**
        * @param {VAttribute & { value: VLiteral } } node
        */
-      'VAttribute[directive=false][key.name="class"]'(node) {
+      'VAttribute[directive=false][key.name="class"][value!=null]'(node) {
         for (const className of node.value.value.split(/\s+/)) {
           reportForbiddenClass(
             className,

Diff for: tests/lib/rules/no-restricted-class.js

@@ -18,6 +18,8 @@ const ruleTester = new RuleTester({
 ruleTester.run('no-restricted-class', rule, {
   valid: [
     `<template><div class="allowed">Content</div></template>`,
+    `<template><div class>Content</div></template>`,
+    `<template><div :class>Content</div></template>`,
     {
       code: `<template><div class="allowed"">Content</div></template>`,
       options: ['forbidden']