assertNull("Method addPosition should not have added a value as " +
"only Lengths with pixel units are valid", position);
// Test with StyleLength values.
StyleLength styleTopLength = styleValueFactory.getLength(null, 50.0, LengthUnit.PX);
properties.setComputedValue(StylePropertyDetails.TOP, styleTopLength);
StyleLength styleLeftLength = styleValueFactory.getLength(null, 25.0, LengthUnit.PX);
properties.setComputedValue(StylePropertyDetails.LEFT, styleLeftLength);
element = domFactory.createElement();
style.addPosition(element, "pos");