var assert = require("../assert");

module.exports = {
  topic: function(d3) {
    var s = d3.select("body").append("div")
        .style("background-color", "white")
        .style("color", "red")
        .style("display", "none")
        .style("font-size", "20px");

    var t = s.transition()
        .style("display", null)
        .style("font-size", function() { return null; })
        .style("display", null)
        .style("background-color", "green")
        .style("background-color", "red")
        .style("color", function() { return "green"; }, "important");

    return {selection: s, transition: t};
  },
  "defines the corresponding style tween": function(result) {
    assert.typeOf(result.transition.tween("style.background-color"), "function");
    assert.typeOf(result.transition.tween("style.color"), "function");
  },
  "on end": {
    topic: function(result) {
      var cb = this.callback;
      result.transition.each("end", function() { cb(null, result); });
    },
    "the last style operator takes precedence": function(result) {
      assert.equal(result.selection.style("background-color"), "#ff0000");
    },
    "sets a property as a string": function(result) {
      assert.equal(result.selection.style("background-color"), "#ff0000");
    },
    "sets a property as a function": function(result) {
      assert.equal(result.selection.style("color"), "#008000");
    },
    "observes the specified priority": function(result) {
      var style = result.selection.node().style;
      assert.equal(style.getPropertyPriority("background-color"), "");
      assert.equal(style.getPropertyPriority("color"), "important");
    },
    "removes a property using a constant null": function(result) {
      assert.equal(result.selection.style("display"), "");
    },
    "removes a property using a function null": function(result) {
      assert.equal(result.selection.style("font-size"), "");
    }
  }
};