var assert = require(“../assert”);

module.exports = {

topic: function(d3) {
  var s = d3.select("body").append("div")
      .attr("display", "none")
      .attr("font-size", "20px")
      .attr("width", 20)
      .attr("color", "red")
      .attr("xlink:type", "simple")
      .attr("xlink:href", "http://mbostock.github.com/d3/");

  var t = s.transition()
      .attr("display", null)
      .attr("font-size", function() { return null; })
      .attr("display", null)
      .attr("width", 100)
      .attr("width", 200)
      .attr("color", function() { return "green"; })
      .attr("xlink:href", null)
      .attr("xlink:type", function() { return null; });

  return {selection: s, transition: t};
},
"defines the corresponding attr tween": function(result) {
  assert.typeOf(result.transition.tween("attr.width"), "function");
  assert.typeOf(result.transition.tween("attr.color"), "function");
},
"on end": {
  topic: function(result) {
    var cb = this.callback;
    result.transition.each("end", function() { cb(null, result); });
  },
  "the last attr operator takes precedence": function(result) {
    assert.equal(result.selection.attr("width"), "200");
  },
  "sets an attribute as a number": function(result) {
    assert.equal(result.selection.attr("width"), "200");
  },
  "sets an attribute as a function": function(result) {
    assert.equal(result.selection.attr("color"), "#008000");
  },
  "removes an attribute using a constant null": function(result) {
    assert.isNull(result.selection.attr("display"));
  },
  "removes an attribute using a function null": function(result) {
    assert.isNull(result.selection.attr("font-size"));
  },
  "removes a namespaced attribute using a constant null": function(result) {
    assert.isNull(result.selection.attr("xlink:href"));
  },
  "removes a namespaced attribute using a function null": function(result) {
    assert.isNull(result.selection.attr("xlink:type"));
  }
}

};