### Question:
PersistentContactService extends AbstractService implements ContactService { @Override public List<Contact> allContacts() { return Lists.newArrayList(contacts); } PersistentContactService(WalletPassword walletPassword);   PersistentContactService(EncryptedContactsFile backingStoreFile, CharSequence password); @Override Contact newContact(String name); @Override List<Contact> allContacts(); @Override List<Contact> filterContactsByBitcoinAddress(Address address); @Override List<Contact> filterContactsByContent(String query, boolean excludeNotPayable); @Override Optional<Contact> filterContactsForSingleMatch(String query, boolean excludeNotPayable); @Override void addAll(Collection<Contact> selectedContacts); @Override void loadContacts(CharSequence password); @Override void removeAll(Collection<Contact> selectedContacts); @Override void updateContacts(Collection<Contact> editedContacts); @Override void writeContacts(); @Override void addDemoContacts();  }### Answer:
@Test public void testAllContacts() throws Exception { List<Contact> allContacts = contactService.allContacts(); assertThat(allContacts.size()).isEqualTo(6); }