### Question:
Or extends ERE { static public ERE get(List<ERE> children) { Or or = new Or(children); ERE ret = or.simplify(); return ret; } private  Or(List<ERE> children); static ERE get(List<ERE> children); ERE simplify(); @Override EREType getEREType(); @Override String toString(); @Override ERE copy(); @Override boolean containsEpsilon(); @Override ERE derive(Symbol s);  }### Answer:
@Test public void testEquality() { ERE or_again = Or.get(new ArrayList<ERE>(Arrays.asList(a, b))); ERE or_reverse = Or.get(new ArrayList<ERE>(Arrays.asList(a, b))); assertEquals(aOrb, or_again); assertEquals(0, aOrb.compareTo(or_again)); assertEquals(aOrb, or_reverse); assertEquals(0, aOrb.compareTo(or_reverse)); }
@Test public void testInequality() { Symbol c = Symbol.get("c"); ERE aOrc = Or.get(new ArrayList<ERE>(Arrays.asList(a, c))); assertFalse(aOrb.equals(aOrc)); assertFalse(0 == aOrb.compareTo(aOrc)); assertFalse(aOrb.equals(a)); assertFalse(0 == aOrb.compareTo(a)); }