require("../env");

require("../../d3");

var assert = require("assert");

module.exports = {

  topic: function() {

    var s = d3.select("body").append("div").selectAll("div")

        .data(["one", "two", "three", "four"])

      .enter().append("div")

        .attr("class", String);

    s.filter(function(d, i) { return i > 0; }).append("span");

    s[0][3] = null;

    return s.transition()

        .delay(function(d, i) { return i * 13; })

        .duration(function(d, i) { return i * 21; });

  },

  "selects the first matching element": function(transition) {

    var t = transition.select("span");

    assert.domEqual(t[0][1].node.parentNode, transition[0][1].node);

    assert.domEqual(t[0][2].node.parentNode, transition[0][2].node);

  },

  "ignores null elements": function(transition) {

    var t = transition.select("span");

    assert.isNull(t[0][3]);

  },

  "propagates data to the selected elements": function(transition) {

    var t = transition.select("span");

    assert.equal(t[0][1].node.__data__, "two");

    assert.equal(t[0][2].node.__data__, "three");

  },

  "propagates delay to the selected elements": function(transition) {

    var t = transition.select("span");

    assert.equal(t[0][1].delay, 13);

    assert.equal(t[0][2].delay, 26);

  },

  "propagates duration to the selected elements": function(transition) {

    var t = transition.select("span");

    assert.equal(t[0][1].duration, 21);

    assert.equal(t[0][2].duration, 42);

  },

  "does not propagate data if no data was specified": function(transition) {

    delete transition[0][1].node.__data__;

    delete transition[0][1].node.firstChild.__data__;

    var t = transition.select("span");

    assert.isUndefined(t[0][1].node.__data__);

    assert.equal(t[0][2].node.__data__, "three");

  },

  "returns null if no match is found": function(transition) {

    var t = transition.select("span");

    assert.isNull(t[0][0]);

  },

  "inherits transition id": function(transition) {

    var id = transition.id,

        t0 = transition.select("span"),

        t1 = transition.select("span");

    assert.equal(t0.id, id);

    assert.equal(t1.id, id);

  }

};