Add test for transition.

test/core/test-transition.js

@@ -1,18 +0,0 @@
-require("./../../lib/env-js/envjs/node");
-require("./../../lib/sizzle/sizzle");
-require("./../../d3");
-
-var body = d3.select("body")
-    .style("background-color", "white");
-
-console.log("transition start:");
-console.log("  ", body.style("background-color"));
-console.log("");
-
-body.transition()
-    .style("background-color", "red")
-    .each("end", function() {
-      console.log("transition end:");
-      console.log("  ", body.style("background-color"));
-      console.log("");
-    });

test/core/test-transition.out

@@ -1,6 +0,0 @@
-transition start:
-   white
-
-transition end:
-   rgb(255,0,0)
-

test/core/transition-test.js

@@ -0,0 +1,44 @@
+require("../env");
+require("../../d3");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.transition");
+
+suite.addBatch({
+  "transition.style": {
+    topic: function() {
+      var callback = this.callback,
+          div = d3.select("body").append("div");
+
+      div
+          .style("background-color", "white")
+        .transition()
+          .style("background-color", "red")
+          .each("end", function() { callback(null, div); });
+    },
+    "sets a property as a string": function(div) {
+      assert.equal(div.style("background-color"), "rgb(255,0,0)");
+    }
+  },
+  "transition.attr": {
+    topic: function() {
+      var callback = this.callback,
+          div = d3.select("body").append("div");
+
+      div
+          .attr("width", 20)
+        .transition()
+          .attr("width", 200)
+          .each("end", function() { callback(null, div); });
+    },
+    "sets an attribute as a number": function(div) {
+      assert.equal(div.attr("width"), "200");
+    }
+  }
+});
+
+// TODO There's a lot more to test here!
+
+suite.export(module);