fix(no-useless-mustaches): escape < in fixes

Author: DMartens

lib/rules/no-useless-mustaches.js

@@ -142,8 +142,9 @@ module.exports = {
             // It doesn't autofix because another rule like indent or eol space might remove spaces.
             return null
           }
+          const escaped = text.replace(/\</g, '&lt;');
 
-          return fixer.replaceText(node, text.replace(/\\([\S\s])/g, '$1'))
+          return fixer.replaceText(node, escaped.replace(/\\([\S\s])/g, '$1'))
         }
       })
     }

tests/lib/rules/no-useless-mustaches.js

@@ -186,6 +186,54 @@ tester.run('no-useless-mustaches', rule, {
         'Unexpected mustache interpolation with a string literal value.'
       ]
     },
+    {
+      code: `
+      <template>
+        {{ '&lt;' }}
+        {{ '&gt;' }}
+        {{ '&amp;' }}
+        {{ '&#8212;' }}
+      </template>
+      `,
+      output: `
+      <template>
+        &lt;
+        &gt;
+        &amp;
+        &#8212;
+      </template>
+      `,
+      errors: [
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+      ]
+    },
+    {
+      code: `
+      <template>
+        {{ '<' }}
+        {{ '<<' }}
+        {{ 'can be < anywhere' }}
+        {{ '<tag>' }}
+      </template>
+      `,
+      output: `
+      <template>
+        &lt;
+        &lt;&lt;
+        can be &lt; anywhere
+        &lt;tag>
+      </template>
+      `,
+      errors: [
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+        'Unexpected mustache interpolation with a string literal value.',
+      ]
+    },
     {
       code: `
       <template>