### Question:
NmeaSentence { public String getDgpsId(){ if (isGGA()) { if (nmeaParts.length > 14 &&!Strings.isNullOrEmpty(nmeaParts[14]) && !nmeaParts[14].startsWith("*")) { return nmeaParts[14].split("\\*")[0]; } } return null; } NmeaSentence(String nmeaSentence); boolean isLocationSentence(); String getLatestPdop(); String getLatestVdop(); String getLatestHdop(); String getGeoIdHeight(); String getAgeOfDgpsData(); String getDgpsId();  }### Answer:
@Test public void NmeaSentence_EmptyNmeaSentence_DGPSIDIsNull(){ NmeaSentence nmeaSentence = new NmeaSentence("$GPGGA,,"); assertThat("DGPSID null by default", nmeaSentence.getDgpsId(), nullValue()); nmeaSentence = new NmeaSentence(""); assertThat("DGPSID null by default", nmeaSentence.getDgpsId(), nullValue()); }