### Question:
MacMachineIdProvider implements MachineIdProvider { @Override public long getMachineId() { return machineId; } MacMachineIdProvider(); @Override long getMachineId();  }### Answer:
@Test public void validateProvider() { Assert.assertEquals("Machine id's are not deterministic", new MacMachineIdProvider().getMachineId(), new MacMachineIdProvider().getMachineId()); if(new MacMachineIdProvider().getMachineId() == 0L) { System.err.println("Could not detect MAC address"); } }