如何对使用流的方法进行单元测试？

Question

我是单元测试的新手，我正在寻找一种使用流测试方法的方法，但到目前为止我在互联网上找不到示例。

我在一个服务类中有两个带有流的方法：

public List<Appointment> getAppointmentsForToday() {

    return getAppointmentsForSpecificDoctor().stream()
        .filter(appointment -> appointment.getDate().equals(LocalDate.now()))
        .collect(Collectors.toList());
  }

  public ObservableList<String> getScheduledTime(User pickedDoctor, LocalDate pickedDate) {
    List<Appointment> appointmentsOfDoctor = getAllAppointments()
        .stream()
        .filter(appointment -> appointment.getDoctor().getFirstName().equals(pickedDoctor.getFirstName()))
        .collect(Collectors.toList());

    List<Appointment> appointmentsInSpecificDay = appointmentsOfDoctor
        .stream()
        .filter(appointment -> appointment.getDate().equals(pickedDate))
        .collect(Collectors.toList());

    Iterator<Appointment> it = appointmentsInSpecificDay.iterator();
    ObservableList<String> scheduledHours = FXCollections.observableArrayList();

    while(it.hasNext()) {
      scheduledHours.add(it.next().getTime());
    }

    return scheduledHours;
  }

我应该如何处理这些问题？