diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/extent-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/extent-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,51 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.extent");
+
+suite.addBatch({
+  "extent": {
+    topic: function() {
+      return d3.extent;
+    },
+    "returns the numeric extent for numbers": function(extent) {
+      assert.deepEqual(extent([1]), [1, 1]);
+      assert.deepEqual(extent([5, 1, 2, 3, 4]), [1, 5]);
+      assert.deepEqual(extent([20, 3]), [3, 20]);
+      assert.deepEqual(extent([3, 20]), [3, 20]);
+    },
+    "returns the lexicographic extent for strings": function(extent) {
+      assert.deepEqual(extent(["c", "a", "b"]), ["a", "c"]);
+      assert.deepEqual(extent(["20", "3"]), ["20", "3"]);
+      assert.deepEqual(extent(["3", "20"]), ["20", "3"]);
+    },
+    "ignores null, undefined and NaN": function(extent) {
+      assert.deepEqual(extent([NaN, 1, 2, 3, 4, 5]), [1, 5]);
+      assert.deepEqual(extent([1, 2, 3, 4, 5, NaN]), [1, 5]);
+      assert.deepEqual(extent([10, null, 3, undefined, 5, NaN]), [3, 10]);
+      assert.deepEqual(extent([-1, null, -3, undefined, -5, NaN]), [-5, -1]);
+    },
+    "compares heterogenous types as numbers": function(extent) {
+      assert.deepEqual(extent([20, "3"]), ["3", 20]);
+      assert.deepEqual(extent(["20", 3]), [3, "20"]);
+      assert.deepEqual(extent([3, "20"]), [3, "20"]);
+      assert.deepEqual(extent(["3", 20]), ["3", 20]);
+    },
+    "returns undefined for empty array": function(extent) {
+      assert.deepEqual(extent([]), [undefined, undefined]);
+      assert.deepEqual(extent([null]), [undefined, undefined]);
+      assert.deepEqual(extent([undefined]), [undefined, undefined]);
+      assert.deepEqual(extent([NaN]), [undefined, undefined]);
+      assert.deepEqual(extent([NaN, NaN]), [undefined, undefined]);
+    },
+    "applies the optional accessor function exactly once": function(extent) {
+      var i = 10;
+      assert.deepEqual(d3.extent([0,1,2,3], function() { return ++i; }), [11, 14]);
+    }
+  }
+});
+
+suite.export(module);