question: public void testCase4 ( ) { byte aBytes [ ] = { 3 , 4 , 5 , 6 , 7 , 8 , 9 } ; byte bBytes [ ] = { 1 , 2 , 3 , 4 , 5 , 6 , 7 } ; byte rBytes [ ] = { - 3 , - 3 , - 3 , - 3 , - 3 , - 3 , - 2 } ; int aSign = - 1 ; int bSign = 1 ; BigInteger aNumber = new BigInteger ( aSign , aBytes ) ; BigInteger bNumber = new BigInteger ( bSign , bBytes ) ; BigInteger result = aNumber . add ( bNumber ) ; byte resBytes [ ] = new byte [ rBytes . length ] ; resBytes = result . toByteArray ( ) ; for ( int i = 0 ; i < resBytes . length ; i ++ ) { assertTrue ( resBytes [ i ] == rBytes [ i ] ) ; } assertEquals ( "incorrect sign" , - 1 , result . signum ( ) ) ; }
target:  Add two numbers of the same length. The first one is negative and the second is positive. The first one is greater in absolute value.