diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/time/day-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/time/day-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,65 @@
+require("../env");
+require("../../d3");
+require("../../d3.time");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.time.day");
+
+suite.addBatch({
+  "day": {
+    topic: function() {
+      return d3.time.day;
+    },
+    "returns midnights": function(floor) {
+      assert.deepEqual(floor(local(2010, 11, 31, 23)), local(2010, 11, 31));
+      assert.deepEqual(floor(local(2011, 0, 1, 0)), local(2011, 0, 1));
+      assert.deepEqual(floor(local(2011, 0, 1, 1)), local(2011, 0, 1));
+    },
+    "observes start of daylight savings time": function(floor) {
+      assert.deepEqual(floor(utc(2011, 2, 13, 7)), local(2011, 2, 12));
+      assert.deepEqual(floor(utc(2011, 2, 13, 8)), local(2011, 2, 13));
+      assert.deepEqual(floor(utc(2011, 2, 13, 9)), local(2011, 2, 13));
+      assert.deepEqual(floor(utc(2011, 2, 13, 10)), local(2011, 2, 13));
+    },
+    "observes end of daylight savings time": function(floor) {
+      assert.deepEqual(floor(utc(2011, 10, 6, 7)), local(2011, 10, 6));
+      assert.deepEqual(floor(utc(2011, 10, 6, 8)), local(2011, 10, 6));
+      assert.deepEqual(floor(utc(2011, 10, 6, 9)), local(2011, 10, 6));
+      assert.deepEqual(floor(utc(2011, 10, 6, 10)), local(2011, 10, 6));
+    },
+    "UTC": {
+      topic: function(floor) {
+        return floor.utc;
+      },
+      "returns midnights": function(floor) {
+        assert.deepEqual(floor(utc(2010, 11, 31, 23)), utc(2010, 11, 31));
+        assert.deepEqual(floor(utc(2011, 0, 1, 0)), utc(2011, 0, 1));
+        assert.deepEqual(floor(utc(2011, 0, 1, 1)), utc(2011, 0, 1));
+      },
+      "does not observe the start of daylight savings time": function(floor) {
+        assert.deepEqual(floor(utc(2011, 2, 13, 7)), utc(2011, 2, 13));
+        assert.deepEqual(floor(utc(2011, 2, 13, 8)), utc(2011, 2, 13));
+        assert.deepEqual(floor(utc(2011, 2, 13, 9)), utc(2011, 2, 13));
+        assert.deepEqual(floor(utc(2011, 2, 13, 10)), utc(2011, 2, 13));
+      },
+      "does not observe the end of daylight savings time": function(floor) {
+        assert.deepEqual(floor(utc(2011, 10, 6, 5)), utc(2011, 10, 6));
+        assert.deepEqual(floor(utc(2011, 10, 6, 6)), utc(2011, 10, 6));
+        assert.deepEqual(floor(utc(2011, 10, 6, 7)), utc(2011, 10, 6));
+        assert.deepEqual(floor(utc(2011, 10, 6, 8)), utc(2011, 10, 6));
+      }
+    }
+  }
+});
+
+function local(year, month, day, hours, minutes, seconds) {
+  return new Date(year, month, day, hours || 0, minutes || 0, seconds || 0);
+}
+
+function utc(year, month, day, hours, minutes, seconds) {
+  return new Date(Date.UTC(year, month, day, hours || 0, minutes || 0, seconds || 0));
+}
+
+suite.export(module);