public void PositionMassLabel()
        {
            var mass       = new TextOutline("15", font, emSize);
            var positioned = atomGenerator.PositionMassLabel(mass, element);

            var elementBounds = element.GetBounds();
            var massBounds    = positioned.GetBounds();

            Assert.IsTrue(massBounds.Right < elementBounds.Left);
            Assert.AreEqual(elementBounds.Top, massBounds.CenterY(), 0.01);
        }