### Question:
Utils { public static DateTime receiverTimeToDateTime(long deltaInSeconds) { int offset = DateTimeZone.getDefault().getOffset(DEXCOM_EPOCH) - DateTimeZone.getDefault().getOffset(Instant.now()); return DEXCOM_EPOCH.plus(offset).plus(standardSeconds(deltaInSeconds)).withZone(DateTimeZone.UTC); }  static DateTime receiverTimeToDateTime(long deltaInSeconds); static Date receiverTimeToDate(long delta); static String getTimeAgoString(Period period); static String getTimeString(long timeDeltaMS); static List<GlucoseDataSet> mergeGlucoseDataRecords(List<SensorGlucoseValueEntry> egvRecords,
                                                               List<SensorEntry> sensorRecords); static String bytesToHex(byte[] bytes); static final DateTime DEXCOM_EPOCH; }### Answer:
@Test public void testReceiverTimeToDateTime_epoch() { assertThat(Utils.receiverTimeToDateTime(0), is(Utils.DEXCOM_EPOCH.withZone(DateTimeZone.UTC))); }
@Test public void testReceiverTimeToDateTime_positiveDelta() { int secondsDelta = 10; assertThat(Utils.receiverTimeToDateTime(secondsDelta), is(Utils.DEXCOM_EPOCH.plusSeconds(secondsDelta).withZone(DateTimeZone.UTC))); }
@Test public void testReceiverTimeToDateTime_negativeDelta() { int secondsDelta = -10; assertThat(Utils.receiverTimeToDateTime(secondsDelta), is(Utils.DEXCOM_EPOCH.minusSeconds(10).withZone(DateTimeZone.UTC))); }