text: 'use strict';
  // https://github.com/nodejs/node/issues/10223
  
  require('../common');
  const assert = require('assert');
  const vm = require('vm');
  
  const ctx = vm.createContext();
  vm.runInContext('Object.defineProperty(this, "x", { value: 42 })', ctx);
  assert.strictEqual(vm.runInContext('x', ctx), 42);
  vm.runInContext('x = 0', ctx);                      // Does not throw but x...
  assert.strictEqual(vm.runInContext('x', ctx), 42);  // ...should be unaltered.
  assert.throws(() => vm.runInContext('"use strict"; x = 0', ctx),
                /Cannot assign to read only property 'x'/);
  assert.strictEqual(vm.runInContext('x', ctx), 42);
  