如何使用Junit測試Java中的插入操作

Question

我得到了一項任務，要使用 MySQL 執行 JDBC CRUD 操作，

這是我得到的示例代碼，

數據庫設置：

CREATE DATABASE 'demo';
USE demo;

create table users (
    id  int(3) NOT NULL AUTO_INCREMENT,
    name varchar(120) NOT NULL,
    email varchar(220) NOT NULL,
    country varchar(120),
    PRIMARY KEY (id)
);

package net.javaguides.usermanagement.dao;

增刪改查文件：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import net.javaguides.usermanagement.model.User;

/**
 * AbstractDAO.java This DAO class provides CRUD database operations for the
 * table users in the database.
 * 
 * @author sourcecodeexamples
 *
 */
public class UserDAO {
    private String jdbcURL = "jdbc:mysql://localhost:3306/demo?useSSL=false";
    private String jdbcUsername = "root";
    private String jdbcPassword = "root";

    private static final String INSERT_USERS_SQL = "INSERT INTO users" + "  (name, email, country) VALUES " +
        " (?, ?, ?);";

    private static final String SELECT_USER_BY_ID = "select id,name,email,country from users where id =?";
    private static final String SELECT_ALL_USERS = "select * from users";
    private static final String DELETE_USERS_SQL = "delete from users where id = ?;";
    private static final String UPDATE_USERS_SQL = "update users set name = ?,email= ?, country =? where id = ?;";

    public UserDAO() {}

    protected Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(jdbcURL, jdbcUsername, jdbcPassword);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return connection;
    }

    public void insertUser(User user) throws SQLException {
        System.out.println(INSERT_USERS_SQL);
        // try-with-resource statement will auto close the connection.
        try (Connection connection = getConnection(); PreparedStatement preparedStatement = connection.prepareStatement(INSERT_USERS_SQL)) {
            preparedStatement.setString(1, user.getName());
            preparedStatement.setString(2, user.getEmail());
            preparedStatement.setString(3, user.getCountry());
            System.out.println(preparedStatement);
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            printSQLException(e);
        }
    }

    public User selectUser(int id) {
        User user = null;
        // Step 1: Establishing a Connection
        try (Connection connection = getConnection();
            // Step 2:Create a statement using connection object
            PreparedStatement preparedStatement = connection.prepareStatement(SELECT_USER_BY_ID);) {
            preparedStatement.setInt(1, id);
            System.out.println(preparedStatement);
            // Step 3: Execute the query or update query
            ResultSet rs = preparedStatement.executeQuery();

            // Step 4: Process the ResultSet object.
            while (rs.next()) {
                String name = rs.getString("name");
                String email = rs.getString("email");
                String country = rs.getString("country");
                user = new User(id, name, email, country);
            }
        } catch (SQLException e) {
            printSQLException(e);
        }
        return user;
    }

    public List < User > selectAllUsers() {

        // using try-with-resources to avoid closing resources (boiler plate code)
        List < User > users = new ArrayList < > ();
        // Step 1: Establishing a Connection
        try (Connection connection = getConnection();

            // Step 2:Create a statement using connection object
            PreparedStatement preparedStatement = connection.prepareStatement(SELECT_ALL_USERS);) {
            System.out.println(preparedStatement);
            // Step 3: Execute the query or update query
            ResultSet rs = preparedStatement.executeQuery();

            // Step 4: Process the ResultSet object.
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                String email = rs.getString("email");
                String country = rs.getString("country");
                users.add(new User(id, name, email, country));
            }
        } catch (SQLException e) {
            printSQLException(e);
        }
        return users;
    }

    public boolean deleteUser(int id) throws SQLException {
        boolean rowDeleted;
        try (Connection connection = getConnection(); PreparedStatement statement = connection.prepareStatement(DELETE_USERS_SQL);) {
            statement.setInt(1, id);
            rowDeleted = statement.executeUpdate() > 0;
        }
        return rowDeleted;
    }

    public boolean updateUser(User user) throws SQLException {
        boolean rowUpdated;
        try (Connection connection = getConnection(); PreparedStatement statement = connection.prepareStatement(UPDATE_USERS_SQL);) {
            statement.setString(1, user.getName());
            statement.setString(2, user.getEmail());
            statement.setString(3, user.getCountry());
            statement.setInt(4, user.getId());

            rowUpdated = statement.executeUpdate() > 0;
        }
        return rowUpdated;
    }

    private void printSQLException(SQLException ex) {
        for (Throwable e: ex) {
            if (e instanceof SQLException) {
                e.printStackTrace(System.err);
                System.err.println("SQLState: " + ((SQLException) e).getSQLState());
                System.err.println("Error Code: " + ((SQLException) e).getErrorCode());
                System.err.println("Message: " + e.getMessage());
                Throwable t = ex.getCause();
                while (t != null) {
                    System.out.println("Cause: " + t);
                    t = t.getCause();
                }
            }
        }
    }
}

現在的問題是他們要求對插入操作進行 JUnit 測試。 我對這個 Java 域完全陌生，所以任何人都可以提供信息，我需要在此代碼中包含哪些內容。

Answer 1

我推薦一個關於 JUnit 5 的教程。

以下是一些可嘗試的步驟：

1. 將 JUnit 5 添加到您的項目依賴項中。 如果你使用Maven 就很容易做到。
2. 將新的 JUnit class 添加到與UserDAO相同的 package 中的/test文件夾中。
3. 為 UserDAOTest class 提供UserDAO class 的實例並調用其方法。 創建快樂路徑和失敗測試用例，以確保 class 在所有情況下都正常運行。

這是一個開始的模板：

public class UserDAOTest {

    // You have to initialize this object
    private UserDAO userDao;

    @Test
    public void testInsert_Success() {
        // setup
        // Initialize test user data
        User expected = new User();
        // exercise
        this.userDAO.insertUser(expected);
        // assert
        User actual = this.userDAO.selectUser(expected.getId());
        Assertions.assertEquals(expected, actual);
    }
}