Code Source:

java-test-tutorial/src at main · Woomin-Wang/java-test-tutorial

• 📂 student
• 📂 test/java/io/wisoft/student

public record Student(String id, String name) {
}

💡 StudentResult가 필요할까?

Student만을 사용하여 성공 시에는 객체를 반환하고, 실패 시나리오(유효하지 않은 입력, 중복 ID 등)에서는 각각의 의미에 맞는 예외(IllegalArgumentException, IllegalStateException)를 던지도록 StudentServiceImpl을 설계하는 것이 좋다.

public class StudentServiceImpl implements StudentService {

    private final Map<String, Student> studentMap;

    public StudentServiceImpl(Map<String, Student> studentMap) {
        this.studentMap = studentMap;
    }

    @Override
    public Student create(String id, String name) {
        validateInput(id, name);

        Student newStudent = new Student(id, name);
        Student existingStudent = studentMap.putIfAbsent(id, newStudent);

        if (existingStudent != null) {
            throw new IllegalStateException("ID already exists: " + id);
        }
        return newStudent;
    }

    @Override
    public void remove(String id) {
        validateInput(id);

        Student removedStudent = studentMap.remove(id);

        if (removedStudent == null) {
            throw new IllegalStateException("ID does not exist: " + id);
        }
    }

    private void validateInput(String id, String name) {
        if (StringUtils.isBlank(id) || StringUtils.isBlank(name)) {
            throw new IllegalArgumentException("Student ID and name cannot be blank.");
        }
    }

    private void validateInput(String id) {
        if (StringUtils.isBlank(id)) {
            throw new IllegalArgumentException("Student ID cannot be blank.");
        }
    }
}