harness.checkPoint("removeAttribute()");
SimpleAttributeSet s = new SimpleAttributeSet();
// remove an attribute that doesn't exist
s.removeAttribute("X1");
s.addAttribute("X1", "Y1");
harness.check(s.getAttribute("X1"), "Y1");
// remove another attribute that doesn't exist
s.removeAttribute("X2");
harness.check(s.getAttributeCount(), 1);
// remove an existing attribute