Function mustNotMutateObjectDeep

test/common/index.js:575–617

(original)

const _mustNotMutateObjectDeepProxies = new WeakMap();

function mustNotMutateObjectDeep(original) {
  // Return primitives and functions directly. Primitives are immutable, and
  // proxied functions are impossible to compare against originals, e.g. with
  // `assert.deepEqual()`.
  if (original === null || typeof original !== 'object') {
    return original;
  }

  const cachedProxy = _mustNotMutateObjectDeepProxies.get(original);
  if (cachedProxy) {
    return cachedProxy;
  }

  const _mustNotMutateObjectDeepHandler = {
    __proto__: null,
    defineProperty(target, property, descriptor) {
      assert.fail(`Expected no side effects, got ${inspect(property)} ` +
                  'defined');
    },
    deleteProperty(target, property) {
      assert.fail(`Expected no side effects, got ${inspect(property)} ` +
                  'deleted');
    },
    get(target, prop, receiver) {
      return mustNotMutateObjectDeep(Reflect.get(target, prop, receiver));
    },
    preventExtensions(target) {
      assert.fail('Expected no side effects, got extensions prevented on ' +
                  inspect(target));
    },
    set(target, property, value, receiver) {
      assert.fail(`Expected no side effects, got ${inspect(value)} ` +
                  `assigned to ${inspect(property)}`);
    },
    setPrototypeOf(target, prototype) {
      assert.fail(`Expected no side effects, got set prototype to ${prototype}`);
    },
  };

  const proxy = new Proxy(original, _mustNotMutateObjectDeepHandler);
  _mustNotMutateObjectDeepProxies.set(original, proxy);
  return proxy;
}

function printSkipMessage(msg) {
  console.log(`1..0 # Skipped: ${msg}`);