diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/keys-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/keys-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,31 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.keys");
+
+suite.addBatch({
+  "keys": {
+    topic: function() {
+      return d3.keys;
+    },
+    "enumerates every defined key": function(keys) {
+      assert.deepEqual(keys({a: 1, b: 1}), ["a", "b"]);
+    },
+    "includes keys defined on prototypes": function(keys) {
+      function abc() {
+        this.a = 1;
+        this.b = 2;
+      }
+      abc.prototype.c = 3;
+      assert.deepEqual(keys(new abc()), ["a", "b", "c"]);
+    },
+    "includes keys with null or undefined values": function(keys) {
+      assert.deepEqual(keys({a: undefined, b: null, c: NaN}), ["a", "b", "c"]);
+    }
+  }
+});
+
+suite.export(module);