diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/timer-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/timer-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,62 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.timer");
+
+suite.addBatch({
+  "timer": {
+    topic: function() {
+      return d3.timer;
+    },
+    "with no delay": {
+      topic: timer(),
+      "first calls after 17 ms or less": function(info) {
+        assert.inDelta(info.start - info.scheduled, 17, 20);
+      },
+      "calls until the function returns true": function(info) {
+        assert.equal(info.count, 4);
+      },
+      "calls every 17 ms": function(info) {
+        assert.inDelta(info.stop - info.start, 17 * 3, 20);
+      }
+    },
+    "with a specified delay": {
+      topic: timer(250),
+      "first calls after the delay": function(info) {
+        assert.inDelta(info.start - info.scheduled, 250, 20);
+      },
+      "calls until the function returns true": function(info) {
+        assert.equal(info.count, 4);
+      },
+      "calls every 17 ms": function(info) {
+        assert.inDelta(info.stop - info.start, 17 * 3, 20);
+      }
+    }
+  }
+});
+
+function timer(delay) {
+  var args = Array.prototype.slice.call(arguments);
+  return function() {
+    var cb = this.callback,
+        info = {scheduled: Date.now(), count: 0};
+
+    args.unshift(function() {
+      var count = ++info.count;
+      if (count === 1) {
+        info.start = Date.now();
+      } else if (count === 4) {
+        info.stop = Date.now();
+        cb(null, info);
+        return true;
+      }
+    });
+
+    d3.timer.apply(this, args);
+  };
+}
+
+suite.export(module);