@Test
public void positionMassLabel() {

    TextOutline mass = new TextOutline("15", font);
    TextOutline positioned = atomGenerator.positionMassLabel(mass, element);
    Rectangle2D elementBounds = element.getBounds();
    Rectangle2D massBounds = positioned.getBounds();
    assertThat(massBounds.getMaxX(), lessThan(elementBounds.getMinX()));
    assertThat(massBounds.getCenterY(), closeTo(elementBounds.getMinY(), 0.01));
}