Conditionally use Object.is shim

Author: lukechilds

assert.js

@@ -35,6 +35,7 @@ const { inspect } = require('util/');
 const { isPromise, isRegExp } = require('util/').types;
 
 const objectAssign = Object.assign ? Object.assign : require('es6-object-assign').assign;
+const objectIs = Object.is ? Object.is : require('object-is');
 
 const errorCache = new Map();
 
@@ -274,7 +275,7 @@ assert.strictEqual = function strictEqual(actual, expected, message) {
   if (arguments.length < 2) {
     throw new ERR_MISSING_ARGS('actual', 'expected');
   }
-  if (!Object.is(actual, expected)) {
+  if (!objectIs(actual, expected)) {
     innerFail({
       actual,
       expected,
@@ -289,7 +290,7 @@ assert.notStrictEqual = function notStrictEqual(actual, expected, message) {
   if (arguments.length < 2) {
     throw new ERR_MISSING_ARGS('actual', 'expected');
   }
-  if (Object.is(actual, expected)) {
+  if (objectIs(actual, expected)) {
     innerFail({
       actual,
       expected,

internal/util/comparisons.js

@@ -5,6 +5,8 @@
 
 const regexFlagsSupported = /a/g.flags !== undefined;
 
+const objectIs = Object.is ? Object.is : require('object-is');
+
 function uncurryThis(f) {
   return f.call.bind(f);
 }
@@ -98,7 +100,7 @@ function areEqualArrayBuffers(buf1, buf2) {
 function isEqualBoxedPrimitive(val1, val2) {
   if (isNumberObject(val1)) {
     return isNumberObject(val2) &&
-           Object.is(Number.prototype.valueOf.call(val1),
+           objectIs(Number.prototype.valueOf.call(val1),
                      Number.prototype.valueOf.call(val2));
   }
   if (isStringObject(val1)) {
@@ -141,7 +143,7 @@ function innerDeepEqual(val1, val2, strict, memos) {
   if (val1 === val2) {
     if (val1 !== 0)
       return true;
-    return strict ? Object.is(val1, val2) : true;
+    return strict ? objectIs(val1, val2) : true;
   }
 
   // Check more closely if val1 and val2 are equal.

package.json

@@ -32,6 +32,7 @@
   "dependencies": {
     "buffer": "^5.2.1",
     "es6-object-assign": "^1.1.0",
+    "object-is": "^1.0.1",
     "util": "^0.12.0"
   }
 }