From e0ee3def233b2ea316a0af83733f57b44440cf1b Mon Sep 17 00:00:00 2001
From: Dai <dai.williams@bbc.co.uk>
Date: Mon, 29 Jun 2015 23:15:14 +0100
Subject: [PATCH] Added handling for undefined and null (fails on negate flag
 too)

---
 lib/chai/core/assertions.js | 12 +++++++-----
 test/expect.js              | 29 +++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
index d38aaae..30e68a2 100644
--- a/lib/chai/core/assertions.js
+++ b/lib/chai/core/assertions.js
@@ -510,14 +510,16 @@ module.exports = function (chai, _) {
     var obj = flag(this, 'object')
       , expected = obj;
 
-    if (Array.isArray(obj) || 'string' === typeof object) {
-      expected = obj.length;
-    } else if (typeof obj === 'object') {
-      expected = Object.keys(obj).length;
+    if (obj == null) {
+      expected = flag(this, 'negate');
+    } else if (Array.isArray(obj) || 'string' === typeof obj) {
+      expected = obj.length === 0;
+    } else if ('object' === typeof obj) {
+      expected = Object.keys(obj).length === 0;
     }
 
     this.assert(
-        !expected
+      expected
       , 'expected #{this} to be empty'
       , 'expected #{this} not to be empty'
     );
diff --git a/test/expect.js b/test/expect.js
index 42b50e6..e152cf6 100644
--- a/test/expect.js
+++ b/test/expect.js
@@ -471,6 +471,35 @@ describe('expect', function () {
     err(function(){
       expect({foo: 'bar'}).to.be.empty;
     }, "expected { foo: \'bar\' } to be empty");
+
+    err(function(){
+      expect(0).to.be.empty;
+    }, "expected 0 to be empty");
+
+    err(function(){
+      expect(null).to.be.empty;
+    }, "expected null to be empty");
+
+    err(function(){
+      expect(undefined).to.be.empty;
+    }, "expected undefined to be empty");
+
+    err(function(){
+      expect().to.be.empty;
+    }, "expected undefined to be empty");
+
+    err(function(){
+      expect(null).to.not.be.empty;
+    }, "expected null not to be empty");
+
+    err(function(){
+      expect(undefined).to.not.be.empty;
+    }, "expected undefined not to be empty");
+
+    err(function(){
+      expect().to.not.be.empty;
+    }, "expected undefined not to be empty");
+    
   });
 
   it('NaN', function() {