describe('chart body', function () {
        it('should create body g', function () {
            chart.render();
            expect(chartBody()).not.toBeEmpty();
        });

        it('should translate to (left, top)', function () {
            chart.render();
             expect(chartBody().attr('transform')).toBe('translate(30,10)')
        });
    });

    describe('bars', function () {
        beforeEach(function () {
            chart.data(data).width(100).height(100)
                .x(d3.scale.linear().domain([0, 3]))
                .y(d3.scale.linear().domain([0, 6]))
                .render();
        });

        it('should create 3 svg:rect elements', function () {
            expect(bars().size()).toBe(3);
        });

        it('should calculate bar width automatically', 
          function () {
            bars().each(function () {expect(d3.select(this).attr('width')).toBe('18'),
            });
        });

       it('should map bar x using x-scale', function () {expect(d3.select(bars()[0][0]).attr('x')).toBe('0'),expect(d3.select(bars()[0][1]).attr('x')).toBe('20'),expect(d3.select(bars()[0][2]).attr('x')).toBe('40'),
       });

       it('should map bar y using y-scale', function () {expect(d3.select(bars()[0][0]).attr('y')).toBe('60'),expect(d3.select(bars()[0][1]).attr('y')).toBe('30'),expect(d3.select(bars()[0][2]).attr('y')).toBe('0'),
       });

       it('should calculate bar height based on y', 
          function () {expect(d3.select(bars()[0][0]).
            attr('height')).toBe('10'),expect(d3.select(bars()[0][1]).attr('height')).toBe('40'),expect(d3.select(bars()[0][2]).attr('height')).toBe('70'),
        });
    });

 	 function chartBody() {
        return svg().select('g.body'),
    }

    function bars() {
        return chartBody().selectAll('rect.bar'),
}

...
var _parent = p, _width = 500, _height = 350,
        _margins = {top: 10, left: 30, right: 10, bottom: 30},
        _data,
        _x = d3.scale.linear(),
        _y = d3.scale.linear();

that.render = function () {
        var svg = _parent
            .append("svg")
            .attr("height", _height)
            .attr("width", _width);

        var body = svg.append("g")
            .attr("class", 'body')
            .attr("transform", "translate(" + _margins.left + "," + _margins.top + ")")

        if (_data) {
            _x.range([0, quadrantWidth()]);
            _y.range([quadrantHeight(), 0]);

            body.selectAll('rect.bar')
                .data(_data).enter()
                .append('rect')
                .attr("class", 'bar')
                .attr("width", function () {
                    return quadrantWidth() / _data.length - BAR_PADDING;
                })
                .attr("x", function (d) {return _x(d.x); })
                .attr("y", function (d) {return _y(d.y); })
                .attr("height", function (d) {
                    return _height - _margins.bottom - _y(d.y);
                });
        }
};
...