diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/test/core/selection-data-test.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/test/core/selection-data-test.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,168 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("selection.data");
+
+suite.addBatch({
+  "select(body)": {
+    topic: function() {
+      return d3.select("body").html("");
+    },
+    "assigns data as an array": function(body) {
+      var data = new Object();
+      body.data([data]);
+      assert.strictEqual(document.body.__data__, data);
+    },
+    "assigns data as a function": function(body) {
+      var data = new Object();
+      body.data(function() { return [data]; });
+      assert.strictEqual(document.body.__data__, data);
+    },
+    "stores data in the DOM": function(body) {
+      var expected = new Object(), actual;
+      document.body.__data__ = expected;
+      body.each(function(d) { actual = d; });
+      assert.strictEqual(actual, expected);
+    },
+    "returns a new selection": function(body) {
+      assert.isFalse(body.data([1]) === body);
+    }
+  }
+});
+
+suite.addBatch({
+  "selectAll(div)": {
+    topic: function() {
+      return d3.select("body").html("").selectAll("div").data(d3.range(2)).enter().append("div");
+    },
+    "assigns data as an array": function(div) {
+      var a = new Object(), b = new Object();
+      div.data([a, b]);
+      assert.strictEqual(div[0][0].__data__, a);
+      assert.strictEqual(div[0][1].__data__, b);
+    },
+    "assigns data as a function": function(div) {
+      var a = new Object(), b = new Object();
+      div.data(function() { return [a, b]; });
+      assert.strictEqual(div[0][0].__data__, a);
+      assert.strictEqual(div[0][1].__data__, b);
+    },
+    "stores data in the DOM": function(div) {
+      var a = new Object(), b = new Object(), actual = [];
+      div[0][0].__data__ = a;
+      div[0][1].__data__ = b;
+      div.each(function(d) { actual.push(d); });
+      assert.deepEqual(actual, [a, b]);
+    },
+    "returns a new selection": function(div) {
+      assert.isFalse(div.data([0, 1]) === div);
+    }
+  }
+});
+
+suite.addBatch({
+  "selectAll(div).selectAll(span)": {
+    topic: function() {
+      return d3.select("body").html("").selectAll("div")
+          .data(d3.range(2))
+        .enter().append("div").selectAll("span")
+          .data(d3.range(2))
+        .enter().append("span");
+    },
+    "assigns data as an array": function(span) {
+      var a = new Object(), b = new Object();
+      span.data([a, b]);
+      assert.strictEqual(span[0][0].__data__, a);
+      assert.strictEqual(span[0][1].__data__, b);
+      assert.strictEqual(span[1][0].__data__, a);
+      assert.strictEqual(span[1][1].__data__, b);
+    },
+    "assigns data as a function": function(span) {
+      var a = new Object(), b = new Object(), c = new Object(), d = new Object();
+      span.data(function(z, i) { return i ? [c, d] : [a, b]; });
+      assert.strictEqual(span[0][0].__data__, a);
+      assert.strictEqual(span[0][1].__data__, b);
+      assert.strictEqual(span[1][0].__data__, c);
+      assert.strictEqual(span[1][1].__data__, d);
+    },
+    "evaluates the function once per group": function(span) {
+      var count = 0;
+      span.data(function() { ++count; return [0, 1]; });
+      assert.equal(count, 2);
+    },
+    "defines an update selection for updating data": function(span) {
+      var update = span.data(d3.range(4));
+      assert.equal(update.length, 2);
+      assert.equal(update[0].length, 4);
+      assert.equal(update[1].length, 4);
+      assert.domEqual(update[0][0], span[0][0]);
+      assert.domEqual(update[0][1], span[0][1]);
+      assert.domNull(update[0][2]);
+      assert.domNull(update[0][3]);
+      assert.domEqual(update[1][0], span[1][0]);
+      assert.domEqual(update[1][1], span[1][1]);
+      assert.domNull(update[1][2]);
+      assert.domNull(update[1][3]);
+    },
+    "defines an enter selection for entering data": function(span) {
+      var enter = span.data(d3.range(4)).enter();
+      assert.isFalse(enter.empty());
+      assert.equal(enter.length, 2);
+      assert.equal(enter[0].length, 4);
+      assert.equal(enter[1].length, 4);
+      assert.domNull(enter[0][0]);
+      assert.domNull(enter[0][1]);
+      assert.deepEqual(enter[0][2], {__data__: 2});
+      assert.deepEqual(enter[0][3], {__data__: 3});
+      assert.domNull(enter[1][0]);
+      assert.domNull(enter[1][1]);
+      assert.deepEqual(enter[1][2], {__data__: 2});
+      assert.deepEqual(enter[1][3], {__data__: 3});
+    },
+    "defines an exit selection for exiting data": function(span) {
+      var exit = span.data(d3.range(1)).exit();
+      assert.isFalse(exit.empty());
+      assert.equal(exit.length, 2);
+      assert.equal(exit[0].length, 2);
+      assert.equal(exit[1].length, 2);
+      assert.domNull(exit[0][0]);
+      assert.domEqual(exit[0][1], span[0][1]);
+      assert.domNull(exit[1][0]);
+      assert.domEqual(exit[1][1], span[1][1]);
+    },
+    "observes the specified key function": function(span) {
+      var update = span.data([1, 2], Number);
+      assert.isFalse(update.empty());
+      assert.equal(update.length, 2);
+      assert.equal(update[0].length, 2);
+      assert.equal(update[1].length, 2);
+      assert.domEqual(update[0][0], span[0][1]);
+      assert.domNull(update[0][1]);
+      assert.domEqual(update[1][0], span[1][1]);
+      assert.domNull(update[1][1]);
+
+      var enter = update.enter();
+      assert.equal(enter.length, 2);
+      assert.equal(enter[0].length, 2);
+      assert.equal(enter[1].length, 2);
+      assert.domNull(enter[0][0]);
+      assert.deepEqual(enter[0][1], {__data__: 2});
+      assert.domNull(enter[1][0]);
+      assert.deepEqual(enter[1][1], {__data__: 2});
+
+      var exit = update.exit();
+      assert.equal(exit.length, 2);
+      assert.equal(exit[0].length, 2);
+      assert.equal(exit[1].length, 2);
+      assert.domEqual(exit[0][0], span[0][0]);
+      assert.domNull(exit[0][1]);
+      assert.domEqual(exit[1][0], span[1][0]);
+      assert.domNull(exit[1][1]);
+    }
+  }
+});
+
+suite.export(module);