### Question:
SimpleUserSystemService implements UserSystemService { @Override public User findUser(String id) { return userById.get(id); } SimpleUserSystemService(); @Override void start(); @Override String getName(); @Override List<User> findAllUsers(); List<Group> findAllGroups(); @Override void test(); @Override User findUser(String id); static final String USERS_FILE; static final String SKILLS_FILE; static final String AFFINITIES_FILE; static final String NAME; }### Answer:
@Test public void findUser() { userSystem.start(); for (String user : USERS) { assertNotNull("User: " + user + " was not found", userSystem.findUser(user)); } }