### Question:
ServerOpts extends ConfigOpts { public String getAddress() { if (address != null) return address; return "0.0.0.0"; }  String getAddress();  }### Answer:
@Test public void testGetAddress() { opts.parseArgs(ServerOptsTest.class.getName(), new String[] {"-a", "1.2.3.4"}); assertEquals("1.2.3.4", opts.getAddress()); }
@Test public void testGetAddress_NOne() { opts.parseArgs(ServerOptsTest.class.getName(), new String[] {}); assertEquals("0.0.0.0", opts.getAddress()); }