### Question:
Join extends Operator { public TupleDesc getTupleDesc() { return desc ; } Join(JoinPredicate p, DbIterator child1, DbIterator child2); JoinPredicate getJoinPredicate(); String getJoinField1Name(); String getJoinField2Name(); TupleDesc getTupleDesc(); void open(); void close(); void rewind(); @Override DbIterator[] getChildren(); @Override void setChildren(DbIterator[] children); static final int blockMemory; }### Answer:
@Test public void getTupleDesc() { JoinPredicate pred = new JoinPredicate(0, Predicate.Op.EQUALS, 0); Join op = new Join(pred, scan1, scan2); TupleDesc expected = Utility.getTupleDesc(width1 + width2); TupleDesc actual = op.getTupleDesc(); assertEquals(expected, actual); }