Detecting a Promise bug in v8 (node 0.11 and 0.12).

v8 bug: https://code.google.com/p/chromium/issues/detail?id=371021
examples: https://gist.github.com/getify/bd11ccf1eff2efdac0fb

The test isn't currently a failing test, because the v8 Promise implementation doesn't support subclassing, which we already detect - but this way we'll explicitly detect both bugs.

es6-shim.js

@@ -1411,9 +1411,18 @@
     // In Chrome 33 (and thereabouts) Promise is defined, but the
     // implementation is buggy in a number of ways.  Let's check subclassing
     // support to see if we have a buggy implementation.
-    if (!supportsSubclassing(globals.Promise, function(S) {
+    var promiseSupportsSubclassing = supportsSubclassing(globals.Promise, function(S) {
       return S.resolve(42) instanceof S;
-    })) {
+    });
+    var promiseIgnoresNonFunctionThenCallbacks = (function () {
+      try {
+        Promise.reject(42).then(null,5).then(null, function () {});
+        return true;
+      } catch (ex) {
+        return false;
+      }
+    }());
+    if (!promiseSupportsSubclassing || !promiseIgnoresNonFunctionThenCallbacks) {
       globals.Promise = PromiseShim;
     }
 

test/index.html

@@ -17,6 +17,7 @@
   <script src="math.js"></script>
   <script src="number.js"></script>
   <script src="object.js"></script>
+  <script src="promise.js"></script>
   <script src="string.js"></script>
   <script src="worker-test.js"></script>
   <script src="promise/all.js"></script>

test/promise.js

@@ -0,0 +1,10 @@
+/* This file is for testing implementation regressions of Promises. */
+
+describe('Promise', function () {
+  it('ignores non-function .then arguments', function () {
+    expect(function () {
+      Promise.reject(42).then(null,5).then(null, function () {});
+    }).not.to.throw();
+  });
+});
+

testling.html

@@ -15,6 +15,7 @@
   <script src="test/math.js"></script>
   <script src="test/number.js"></script>
   <script src="test/object.js"></script>
+  <script src="test/promise.js"></script>
   <script src="test/string.js"></script>
   <script src="test/promise/all.js"></script>
   <script src="test/promise/evil-promises.js"></script>