Fix false positive of eql when some keys set undefined.

CHANGELOG.md

@@ -5,6 +5,9 @@
   demand(undefined).must.be.undefined().
   ```
 
+- Fixes a false positive in [`eql`][] when an object had some keys set to
+  `undefined`.
+
 [`must`]: https://github.com/moll/js-must/blob/master/doc/API.md#Must.prototype.must
 
 ## 0.12.0 (May 28, 2014)

must.js

@@ -520,6 +520,10 @@ function eql(a, b, aStack, bStack) {
       if (aKeys.length != bKeys.length) return false
       if (aKeys.length == 0) return true
 
+      aKeys.sort()
+      bKeys.sort()
+      for (i = 0; i < aKeys.length; ++i) if (aKeys[i] !== bKeys[i]) return false
+
       for (var key in a) if (!eql(a[key], b[key], aStack, bStack)) return false
       return true
   }

test/must/eql_test.js

@@ -304,6 +304,15 @@ describe("Must.prototype.eql", function() {
       assert.fail(function() { Must(a).be.eql(b) })
     })
 
+    // This was a bug I discovered on Jun 12, 2015 related to not comparing
+    // keys equivalence before comparing their values.
+    it("must return false given equal amount of keys undefined keys",
+      function() {
+      var obj = {name: undefined}
+      assert.fail(function() { Must(obj).be.eql({age: undefined}) })
+      assert.fail(function() { Must(obj).be.eql({age: 13}) })
+    })
+
     describe("with circular references", function() {
       it("must pass if equal", function() {
         var a = create({life: {love: 69}})