diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/transition-test-delay.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/transition-test-delay.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,41 @@
+require("../env");
+require("../../d3");
+
+var assert = require("assert");
+
+module.exports = {
+  topic: function() {
+    return d3.select("body").html("").selectAll()
+        .data(["foo", "bar"])
+      .enter().append("div")
+        .attr("class", String);
+  },
+  "defaults to zero": function(selection) {
+    var t = selection.transition();
+    assert.strictEqual(t[0][0].delay, 0);
+    assert.strictEqual(t[0][1].delay, 0);
+  },
+  "can specify delay as a number": function(selection) {
+    var t = selection.transition().delay(150);
+    assert.strictEqual(t[0][0].delay, 150);
+    assert.strictEqual(t[0][1].delay, 150);
+    t.delay(250);
+    assert.strictEqual(t[0][0].delay, 250);
+    assert.strictEqual(t[0][1].delay, 250);
+  },
+  "can specify delay as a function": function(selection) {
+    var dd = [], ii = [], tt = [], t = selection.transition().delay(f);
+    function f(d, i) { dd.push(d); ii.push(i); tt.push(this); return i * 20; }
+    assert.strictEqual(t[0][0].delay, 0);
+    assert.strictEqual(t[0][1].delay, 20);
+    assert.deepEqual(dd, ["foo", "bar"], "expected data, got {actual}");
+    assert.deepEqual(ii, [0, 1], "expected index, got {actual}");
+    assert.domEqual(tt[0], t[0][0].node, "expected this, got {actual}");
+    assert.domEqual(tt[1], t[0][1].node, "expected this, got {actual}");
+  },
+  "coerces delay to a number": function(selection) {
+    var t = selection.transition().delay("150");
+    assert.strictEqual(t[0][0].delay, 150);
+    assert.strictEqual(t[0][1].delay, 150);
+  }
+};