feat(promise): add promise kind and tests

browser.js

@@ -60,6 +60,9 @@ module.exports = function kindOf(val) {
   if (type === '[object Error]') {
     return 'error';
   }
+  if (type === '[object Promise]') {
+    return 'promise';
+  }
 
   // buffer
   if (typeof Buffer !== 'undefined' && isBuffer(val)) {
@@ -117,22 +120,26 @@ module.exports = function kindOf(val) {
 };
 
 },{"is-buffer":2}],2:[function(require,module,exports){
-/**
- * Determine if an object is Buffer
+/*!
+ * Determine if an object is a Buffer
  *
- * Author:   Feross Aboukhadijeh <feross@feross.org> <http://feross.org>
- * License:  MIT
- *
- * `npm install is-buffer`
+ * @author   Feross Aboukhadijeh <feross@feross.org> <http://feross.org>
+ * @license  MIT
  */
 
+// The _isBuffer check is for Safari 5-7 support, because it's missing
+// Object.prototype.constructor. Remove this eventually
 module.exports = function (obj) {
-  return !!(obj != null &&
-    (obj._isBuffer || // For Safari 5-7 (missing Object.prototype.constructor)
-      (obj.constructor &&
-      typeof obj.constructor.isBuffer === 'function' &&
-      obj.constructor.isBuffer(obj))
-    ))
+  return obj != null && (isBuffer(obj) || isSlowBuffer(obj) || !!obj._isBuffer)
+}
+
+function isBuffer (obj) {
+  return !!obj.constructor && typeof obj.constructor.isBuffer === 'function' && obj.constructor.isBuffer(obj)
+}
+
+// For Node v0.10 support. Remove this eventually.
+function isSlowBuffer (obj) {
+  return typeof obj.readFloatLE === 'function' && typeof obj.slice === 'function' && isBuffer(obj.slice(0, 0))
 }
 
 },{}]},{},[1])(1)

index.js

@@ -59,6 +59,9 @@ module.exports = function kindOf(val) {
   if (type === '[object Error]') {
     return 'error';
   }
+  if (type === '[object Promise]') {
+    return 'promise';
+  }
 
   // buffer
   if (typeof Buffer !== 'undefined' && isBuffer(val)) {

test/es6/index.js

@@ -6,6 +6,17 @@ var kindOf = require('../..');
 
 module.exports = function() {
   describe('es6 features', function() {
+    it('should work for resolved promises', function() {
+      var promise = Promise.resolve(123);
+      assert.strictEqual(kindOf(promise), 'promise');
+    });
+
+    it('should work for rejected promises', function() {
+      var promise = Promise.reject(new Error('foo bar'));
+      promise.catch(function() {})
+      assert.strictEqual(kindOf(promise), 'promise');
+    });
+
     it('should work for generators', function() {
       var gen = function * named() {return true;};
       assert.equal(kindOf(gen), 'function');