Customer implements Comparable<Customer> { public void changeBalance(double amount) { balance = amount; } Customer(String nameIn); String getName(); void setLocation(String locationIn); void changeBalance(double amount); String getLocation(); double getBalance(); void setLocation(String city, String state); String toString(); int compareTo(Customer obj);  }
@Test public void changeBalanceTest() { Customer cstmr = new Customer("Lane, Jane"); cstmr.changeBalance(100); Assert.assertEquals(100, cstmr.getBalance(), 0.000001); }