var vows = require(“vows”),

load = require("../load"),
assert = require("../assert");

var suite = vows.describe(“selection.datum”);

suite.addBatch({

"select(body)": {
  topic: load("selection/datum").document(),
  "on a simple page": {
    topic: function(d3) {
      return d3.select("body");
    },
    "updates the data according to the specified function": function(body) {
      body.data([42]).datum(function(d, i) { return d + i; });
      assert.equal(body.node().__data__, 42);
    },
    "updates the data to the specified constant": function(body) {
      body.datum(43);
      assert.equal(body.node().__data__, 43);
    },
    "deletes the data if the function returns null": function(body) {
      body.data([42]).datum(function() { return null; });
      assert.isFalse("__data__" in body.node());
    },
    "deletes the data if the constant is null": function(body) {
      body.data([42]).datum(null);
      assert.isFalse("__data__" in body.node());
    },
    "returns the current selection": function(body) {
      assert.isTrue(body.datum(function() { return 1; }) === body);
      assert.isTrue(body.datum(2) === body);
    },
    "with no arguments, returns the first node's datum": function(body) {
      body.data([42]);
      assert.equal(body.datum(), 42);
    }
  }
}

});

suite.addBatch({

"selectAll(div)": {
  topic: load("selection/datum").document(),
  "on a simple page": {
    topic: function(d3) {
      return d3.select("body").selectAll("div").data([0, 1]).enter().append("div");
    },
    "updates the data according to the specified function": function(div) {
      div.data([42, 43]).datum(function(d, i) { return d + i; });
      assert.equal(div[0][0].__data__, 42);
      assert.equal(div[0][1].__data__, 44);
    },
    "updates the data to the specified constant": function(div) {
      div.datum(44);
      assert.equal(div[0][0].__data__, 44);
      assert.equal(div[0][1].__data__, 44);
    },
    "deletes the data if the function returns null": function(div) {
      div.datum(function() { return null; });
      assert.isFalse("__data__" in div[0][0]);
      assert.isFalse("__data__" in div[0][1]);
    },
    "deletes the data if the constant is null": function(div) {
      div.datum(null);
      assert.isFalse("__data__" in div[0][0]);
      assert.isFalse("__data__" in div[0][1]);
    },
    "returns the current selection": function(div) {
      assert.isTrue(div.datum(function() { return 1; }) === div);
      assert.isTrue(div.datum(2) === div);
    },
    "ignores null nodes": function(div) {
      var node = div[0][1];
      div[0][1] = null;
      div.datum(function() { return 1; });
      assert.equal(div[0][0].__data__, 1);
      assert.equal(node.__data__, 2);
      div.datum(43);
      assert.equal(div[0][0].__data__, 43);
      assert.equal(node.__data__, 2);
    }
  }
}

});

suite.export(module);