require("../env");

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

var vows = require("vows"),

    assert = require("assert");

var suite = vows.describe("d3.mean");

suite.addBatch({

  "mean": {

    topic: function() {

      return d3.mean;

    },

    "returns the mean value for numbers": function(mean) {

      assert.equal(mean([1]), 1);

      assert.equal(mean([5, 1, 2, 3, 4]), 3);

      assert.equal(mean([20, 3]), 11.5);

      assert.equal(mean([3, 20]), 11.5);

    },

    "ignores null, undefined and NaN": function(mean) {

      assert.equal(mean([NaN, 1, 2, 3, 4, 5]), 3);

      assert.equal(mean([1, 2, 3, 4, 5, NaN]), 3);

      assert.equal(mean([10, null, 3, undefined, 5, NaN]), 6);

    },

    "can handle large numbers without overflowing": function(mean) {

      assert.equal(mean([Number.MAX_VALUE, Number.MAX_VALUE]), Number.MAX_VALUE);

      assert.equal(mean([-Number.MAX_VALUE, -Number.MAX_VALUE]), -Number.MAX_VALUE);

    },

    "returns undefined for empty array": function(mean) {

      assert.isUndefined(mean([]));

      assert.isUndefined(mean([null]));

      assert.isUndefined(mean([undefined]));

      assert.isUndefined(mean([NaN]));

      assert.isUndefined(mean([NaN, NaN]));

    },

    "applies the optional accessor function": function(mean) {

      assert.equal(d3.mean([[1, 2, 3, 4, 5], [2, 4, 6, 8, 10]], function(d) { return d3.mean(d); }), 4.5);

      assert.equal(d3.mean([1, 2, 3, 4, 5], function(d, i) { return i; }), 2);

    }

  }

});

suite.export(module);