fix: support canonical module (#5040)

* fix: handle canonicalizing Module

* fix: add tests for canonicalizing a module

* fix: skip module serialization on browser

* fix: handle more generic null prototype instead of Module

* fix: simplify null prototype check

lib/utils.js

@@ -138,7 +138,7 @@ function emptyRepresentation(value, typeHint) {
  * canonicalType(global) // 'global'
  * canonicalType(new String('foo') // 'object'
  * canonicalType(async function() {}) // 'asyncfunction'
- * canonicalType(await import(name)) // 'module'
+ * canonicalType(Object.create(null)) // 'null-prototype'
  */
 var canonicalType = (exports.canonicalType = function canonicalType(value) {
  if (value === undefined) {
@@ -147,7 +147,10 @@ var canonicalType = (exports.canonicalType = function canonicalType(value) {
  return 'null';
  } else if (Buffer.isBuffer(value)) {
  return 'buffer';
+ } else if (Object.getPrototypeOf(value) === null) {
+ return 'null-prototype';
  }
+
  return Object.prototype.toString
  .call(value)
  .replace(/^\[.+\s(.+?)]$/, '$1')
@@ -213,7 +216,7 @@ exports.type = function type(value) {
 exports.stringify = function (value) {
  var typeHint = canonicalType(value);
 
- if (!~['object', 'array', 'function'].indexOf(typeHint)) {
+ if (!~['object', 'array', 'function', 'null-prototype'].indexOf(typeHint)) {
  if (typeHint === 'buffer') {
  var json = Buffer.prototype.toJSON.call(value);
  // Based on the toJSON result
@@ -399,8 +402,12 @@ exports.canonicalize = function canonicalize(value, stack, typeHint) {
  break;
  }
  /* falls through */
+ case 'null-prototype':
  case 'object':
  canonicalizedObj = canonicalizedObj || {};
+ if (typeHint === 'null-prototype' && Symbol.toStringTag in value) {
+ canonicalizedObj['[Symbol.toStringTag]'] = value[Symbol.toStringTag];
+ }
  withStack(value, function () {
  Object.keys(value)
  .sort()

test/unit/utils.spec.js

@@ -288,6 +288,44 @@ describe('lib/utils', function () {
  ].join('\n');
  expect(stringify(expected), 'to be', actual);
  });
+
+ describe('should represent null prototypes', function () {
+ it('With explicit names', function () {
+ const foo = Object.create(null, {
+ [Symbol.toStringTag]: {value: 'Foo'},
+ bing: {get: () => 'bong', enumerable: true}
+ });
+ const expected = [
+ '{',
+ ' "[Symbol.toStringTag]": "Foo"',
+ ' "bing": "bong"',
+ '}'
+ ].join('\n');
+
+ expect(stringify(foo), 'to be', expected);
+ });
+
+ it('Without names', function () {
+ const unnamed = {
+ bing: 'bong',
+ abc: 123
+ };
+ unnamed.self = unnamed;
+ const expected = [
+ '{',
+ ' "abc": 123',
+ ' "bing": "bong"',
+ ' "self": [Circular]',
+ '}'
+ ].join('\n');
+
+ expect(
+ stringify(Object.setPrototypeOf(unnamed, null)),
+ 'to be',
+ expected
+ );
+ });
+ });
  });
 
  it('should canonicalize the object', function () {