@RunWith(MockitoJUnitRunner.class)
public class EmployeesServiceTest {
    
    @Mock
    PSBDataSource mockDataSource;
    @Mock
    Connection mockConn;
    @Mock
    PreparedStatement mockPreparedStmnt;
    @Mock
    ResultSet mockResultSet;
 
    
    @Before
    public void setUp() throws SQLException, NamingException, ServerException {
        InitialContext ctx = Mockito.mock(InitialContext.class);
        when(ctx.lookup("jdbc/psbapp")).thenReturn(mockDataSource);
        doNothing().when(mockConn).commit();
        when(mockConn.prepareStatement(anyString(), anyInt())).thenReturn(mockPreparedStmnt);
        doNothing().when(mockPreparedStmnt).setString(anyInt(), anyString());
        when(mockPreparedStmnt.execute()).thenReturn(Boolean.TRUE);
        when(mockPreparedStmnt.getGeneratedKeys()).thenReturn(mockResultSet);
        when(mockResultSet.next()).thenReturn(Boolean.TRUE, Boolean.FALSE);
    }

    @Test
    public void testСheckRequiredAttribytes() throws ServerException {
       //
        
        EmployeesService employeesService = new EmployeesService();
        List<SaveEmployeeResult> checkResults = employeesService.checkRequiredAttribytes(organization);
        assertNull(checkResults.get(0).getError());
    }

    private Connection getConnection() throws SQLException {
        return PSBDataSource.getInstance().getDataSource().getConnection();
    }

        Hashtable env = new Hashtable();
        env.put(Context.INITIAL_CONTEXT_FACTORY,
                "org.osjava.sj.SimpleJndiContextFactory");
        Context context = new InitialContext(env);
        context.bind("java:comp/env/jdbc/psbapp", new EployeesDataSource());

static class EployeesDataSource implements DataSource {
    
        @Override
        public Connection getConnection() throws SQLException {
            String url= "jdbc:oracle:thin:@db.app.ru:1521:dbname";
            String user = "user";
            String password = "wqeqw";
            try {
                Class.forName("oracle.jdbc.driver.OracleDriver");
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
            Connection connection = null;
            try {
                connection = DriverManager.getConnection(url, user, password);
            } catch (SQLException e) {
                e.printStackTrace();
            }
    
            return connection;
        }
    
        @Override
        public Connection getConnection(String username, String password) throws SQLException {
 ...