1 require("../env");

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

     3 

     4 var assert = require("assert");

     5 

     6 module.exports = {

     7   topic: function() {

     8     return d3.select("body").append("div").transition();

     9   },

    10   "calls the function once": function(transition) {

    11     var count = 0;

    12     transition.call(function() { ++count; });

    13     assert.equal(count, 1);

    14   },

    15   "passes any optional arguments": function(transition) {

    16     var abc;

    17     transition.call(function(selection, a, b, c) { abc = [a, b, c]; }, "a", "b", "c");

    18     assert.deepEqual(abc, ["a", "b", "c"]);

    19   },

    20   "passes the transition as the first argument": function(transition) {

    21     var t;

    22     transition.call(function(x) { t = x; });

    23     assert.isTrue(t === transition);

    24   },

    25   "uses the transition as the context": function(transition) {

    26     var t;

    27     transition.call(function() { t = this; });

    28     assert.isTrue(t === transition);

    29   },

    30   "returns the current transition": function(transition) {

    31     assert.isTrue(transition.call(function() {}) === transition);

    32   }

    33 };