diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/ascending-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/ascending-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,47 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.ascending");
+
+suite.addBatch({
+  "numbers": {
+    "returns a negative number if a < b": function() {
+      assert.isTrue(d3.ascending(0, 1) < 0);
+    },
+    "returns a positive number if a > b": function() {
+      assert.isTrue(d3.ascending(1, 0) > 0);
+    },
+    "returns zero if a == b": function() {
+      assert.equal(d3.ascending(0, 0), 0);
+    },
+    "returns NaN if a or b is undefined": function() {
+      assert.isNaN(d3.ascending(0, undefined));
+      assert.isNaN(d3.ascending(undefined, 0));
+      assert.isNaN(d3.ascending(undefined, undefined));
+    },
+    "returns NaN if a or b is NaN": function() {
+      assert.isNaN(d3.ascending(0, NaN));
+      assert.isNaN(d3.ascending(NaN, 0));
+      assert.isNaN(d3.ascending(NaN, NaN));
+    }
+  }
+});
+
+suite.addBatch({
+  "strings": {
+    "returns a negative number if a < b": function() {
+      assert.isTrue(d3.ascending("a", "b") < 0);
+    },
+    "returns a positive number if a > b": function() {
+      assert.isTrue(d3.ascending("b", "a") > 0);
+    },
+    "returns zero if a == b": function() {
+      assert.equal(d3.ascending("a", "a"), 0);
+    }
+  }
+});
+
+suite.export(module);