### Question:
JDBCUserDatabase extends AbstractUserDatabase { @Override public Principal[] getWikiNames() throws WikiSecurityException { final Set<Principal> principals = new HashSet<>(); try( final Connection conn = m_ds.getConnection(); final PreparedStatement ps = conn.prepareStatement( m_findAll ); final ResultSet rs = ps.executeQuery() ) { while ( rs.next() ) { final String wikiName = rs.getString( m_wikiName ); if( wikiName == null ) { log.warn( "Detected null wiki name in XMLUserDataBase. Check your user database." ); } else { final Principal principal = new WikiPrincipal( wikiName, WikiPrincipal.WIKI_NAME ); principals.add( principal ); } } } catch( final SQLException e ) { throw new WikiSecurityException( e.getMessage(), e ); } return principals.toArray( new Principal[principals.size()] ); }  @Override void deleteByLoginName( final String loginName ); @Override UserProfile findByEmail( final String index ); @Override UserProfile findByFullName( final String index ); @Override UserProfile findByLoginName( final String index ); @Override UserProfile findByUid( final String uid ); @Override UserProfile findByWikiName( final String index ); @Override Principal[] getWikiNames(); @Override void initialize( final Engine engine, final Properties props ); @Override void rename( final String loginName, final String newName ); @Override void save( final UserProfile profile ); static final String DEFAULT_DB_ATTRIBUTES; static final String DEFAULT_DB_CREATED; static final String DEFAULT_DB_EMAIL; static final String DEFAULT_DB_FULL_NAME; static final String DEFAULT_DB_JNDI_NAME; static final String DEFAULT_DB_LOCK_EXPIRY; static final String DEFAULT_DB_MODIFIED; static final String DEFAULT_DB_ROLE; static final String DEFAULT_DB_ROLE_TABLE; static final String DEFAULT_DB_TABLE; static final String DEFAULT_DB_LOGIN_NAME; static final String DEFAULT_DB_PASSWORD; static final String DEFAULT_DB_UID; static final String DEFAULT_DB_WIKI_NAME; static final String PROP_DB_ATTRIBUTES; static final String PROP_DB_CREATED; static final String PROP_DB_EMAIL; static final String PROP_DB_FULL_NAME; static final String PROP_DB_DATASOURCE; static final String PROP_DB_LOCK_EXPIRY; static final String PROP_DB_LOGIN_NAME; static final String PROP_DB_MODIFIED; static final String PROP_DB_PASSWORD; static final String PROP_DB_UID; static final String PROP_DB_ROLE; static final String PROP_DB_ROLE_TABLE; static final String PROP_DB_TABLE; static final String PROP_DB_WIKI_NAME; }### Answer:
@Test public void testGetWikiName() throws WikiSecurityException { Principal[] principals = m_db.getWikiNames(); Assertions.assertEquals( 1, principals.length ); }