var assert = require(“../assert”);

module.exports = {

"with a single element selected": {
  topic: function(d3) {
    return d3.select("body").transition();
  },
  "returns null for empty subselections": function(body) {
    assert.isNull(body.select("foo").node());
  },
  "returns the selected element": function(body) {
    assert.equal(body.node().tagName, "BODY");
  },
  "returns null if no elements are slected": function(body) {
    body[0][0] = null;
    assert.isNull(body.node());
  }
},
"with multiple elements selected": {
  topic: function(d3) {
    var body = d3.select("body").html(null);
    body.append("div").attr("class", "first").append("span");
    body.append("div").attr("class", "second");
    return body.selectAll("div").transition();
  },
  "returns null for empty subselections": function(div) {
    assert.isNull(div.select("foo").node());
  },
  "returns the first selected element": function(div) {
    assert.equal(div.node().className, "first");
    assert.equal(div.node().tagName, "DIV");
  },
  "does not count null nodes": function(div) {
    div[0][0] = null;
    assert.equal(div.node().className, "second");
    assert.equal(div.node().tagName, "DIV");
  }
}

};