### Question:
CouchDBDataStore implements DataStore { @Override public Set<String> getChannelIds(final String uaid) { final ViewResult viewResult = db.queryView(query(Views.UAID.viewName(), uaid)); final List<Row> rows = viewResult.getRows(); if (rows.isEmpty()) { return Collections.emptySet(); } final Set<String> channelIds = new HashSet<String> (rows.size()); for (Row row : rows) { channelIds.add(row.getValueAsNode().get(DOC_FIELD).get(CHID_FIELD).asText()); } return channelIds; } CouchDBDataStore(final String url, final String dbName); @Override void savePrivateKeySalt(final byte[] salt); @Override byte[] getPrivateKeySalt(); @Override boolean saveChannel(final Channel channel); @Override Channel getChannel(final String channelId); @Override void removeChannels(final String uaid); @Override void removeChannels(final Set<String> channelIds); @Override Set<String> getChannelIds(final String uaid); @Override String updateVersion(final String endpointToken, final long version); @Override String saveUnacknowledged(final String channelId, final long version); @Override Set<Ack> getUnacknowledged(final String uaid); @Override Set<Ack> removeAcknowledged(final String uaid, final Set<Ack> acked);  }### Answer:
@Test public void removeChannelIdsEmpty() throws ChannelNotFoundException { final Set<String> channelIds = datastore.getChannelIds(UUIDUtil.newUAID()); assertThat(channelIds.isEmpty(), is(true)); }