diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/mean-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/mean-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,43 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.mean");
+
+suite.addBatch({
+  "mean": {
+    topic: function() {
+      return d3.mean;
+    },
+    "returns the mean value for numbers": function(mean) {
+      assert.equal(mean([1]), 1);
+      assert.equal(mean([5, 1, 2, 3, 4]), 3);
+      assert.equal(mean([20, 3]), 11.5);
+      assert.equal(mean([3, 20]), 11.5);
+    },
+    "ignores null, undefined and NaN": function(mean) {
+      assert.equal(mean([NaN, 1, 2, 3, 4, 5]), 3);
+      assert.equal(mean([1, 2, 3, 4, 5, NaN]), 3);
+      assert.equal(mean([10, null, 3, undefined, 5, NaN]), 6);
+    },
+    "can handle large numbers without overflowing": function(mean) {
+      assert.equal(mean([Number.MAX_VALUE, Number.MAX_VALUE]), Number.MAX_VALUE);
+      assert.equal(mean([-Number.MAX_VALUE, -Number.MAX_VALUE]), -Number.MAX_VALUE);
+    },
+    "returns undefined for empty array": function(mean) {
+      assert.isUndefined(mean([]));
+      assert.isUndefined(mean([null]));
+      assert.isUndefined(mean([undefined]));
+      assert.isUndefined(mean([NaN]));
+      assert.isUndefined(mean([NaN, NaN]));
+    },
+    "applies the optional accessor function": function(mean) {
+      assert.equal(d3.mean([[1, 2, 3, 4, 5], [2, 4, 6, 8, 10]], function(d) { return d3.mean(d); }), 4.5);
+      assert.equal(d3.mean([1, 2, 3, 4, 5], function(d, i) { return i; }), 2);
+    }
+  }
+});
+
+suite.export(module);