Updated dev dependencies & added new tests from the upstream

.eslintrc.js

@@ -1,13 +1,16 @@
-'use strict';
-
 module.exports = {
+    parser: "@babel/eslint-parser",
+    parserOptions: {
+        requireConfigFile: false,
+        babelOptions: {
+            babelrc: false,
+            configFile: false,
+        },
+    },
     extends: ['eslint:recommended'],
     env: {
         node: true
     },
-    parserOptions: {
-        ecmaVersion: 2020
-    },
     rules: {
         strict: ['error'],
         indent: ['error', 4]

lib/index.js

@@ -2,7 +2,6 @@
  * @fileoverview This plugin makes `no-unused-expressions` rule friendly towards chai expect statements.
  * @author Ihor Diachenko
  */
-"use strict";
 
 module.exports = {
     configs: {

lib/rules/no-unused-expressions.js

@@ -3,7 +3,6 @@
  * @author Michael Ficarra
  * @author Ihor Diachenko
  */
-"use strict";
 
 //------------------------------------------------------------------------------
 // Rule Definition
@@ -109,6 +108,12 @@ module.exports = {
             var parent = ancestors[ancestors.length - 1],
                 grandparent = ancestors[ancestors.length - 2];
 
+            /**
+             * https://tc39.es/ecma262/#directive-prologue
+             *
+             * Only `FunctionBody`, `ScriptBody` and `ModuleBody` can have directive prologue.
+             * Class static blocks do not have directive prologue.
+             */
             return (parent.type === "Program" || parent.type === "BlockStatement" &&
                     (/Function/.test(grandparent.type))) &&
                     directives(parent).indexOf(node) >= 0;