### Question:
DatabaseUserGroupProvider implements ConfigurableUserGroupProvider { @Override public Group getGroup(final String groupIdentifier) throws AuthorizationAccessException { Validate.notBlank(groupIdentifier); final DatabaseGroup databaseGroup = getDatabaseGroup(groupIdentifier); if (databaseGroup == null) { return null; } final Set<String> userIdentifiers = getUserIdentifiers(groupIdentifier); return mapToGroup(databaseGroup, userIdentifiers); }  @AuthorizerContext void setDataSource(final DataSource dataSource); @AuthorizerContext void setIdentityMapper(final IdentityMapper identityMapper); @Override void initialize(final UserGroupProviderInitializationContext initializationContext); @Override void onConfigured(final AuthorizerConfigurationContext configurationContext); @Override void preDestruction(); @Override String getFingerprint(); @Override void inheritFingerprint(final String fingerprint); @Override void checkInheritability(final String proposedFingerprint); @Override User addUser(final User user); @Override User updateUser(final User user); @Override Set<User> getUsers(); @Override User getUser(final String identifier); @Override User getUserByIdentity(final String identity); @Override UserAndGroups getUserAndGroups(final String userIdentity); @Override User deleteUser(final User user); @Override Group addGroup(final Group group); @Override Group updateGroup(final Group group); @Override Set<Group> getGroups(); @Override Group getGroup(final String groupIdentifier); @Override Group deleteGroup(final Group group);  }### Answer:
@Test public void testGetGroupWhenDoesNotExist() { configureWithInitialUsers(); final Group group1 = userGroupProvider.getGroup("does-not-exist"); assertNull(group1); }