如何测试对成功和不成功的数据库连接 (JDBC) 的响应？

Question

下面是我的代码。我一直在尝试不同的测试方法，包括存根、嘲笑和间谍。当我尝试模拟 DriverManager.getConnection() 时，我收到一条消息，表明它是私有的。我正在尝试练习 TDD，所以我知道这不是测试连接本身的意图，而是测试连接周围的行为。

public class Main {
 
 
    public static void main(String[] args) {
 
        Datasource datasource = new Datasource();
 
        if(datasource.open() == false){
            return;
        }
 
        datasource.close();
    }
}
 
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
 
public class Datasource {
    public static final String DB_NAME = "DBNAME";
    public static final String DB_USERNAME = "USERNAME";
    public static final String DB_PASSWORD = "PASSWORD";
    public static final String SUBPROTOCOL = "jdbc:oracle:thin:@";
    public static final String SERVER_NAME = "SERVERNAME";
    public static final String PORT_NUMBER = "1521";
    public static final String CONNECTION_STRING = SUBPROTOCOL + SERVER_NAME + ":" + PORT_NUMBER + "/" + DB_NAME;
 
    private Connection conn;
 
    public boolean open(){
        try {
            conn = DriverManager.getConnection(CONNECTION_STRING, DB_USERNAME, DB_PASSWORD);
            System.out.println("Connected to database successfully.");
            return true;
        } catch (SQLException e) {
            System.out.println("Error connecting to database: " + e.getMessage());
            return false;
        }
    }
 
    /**
     * Closes the connection to the HR database.
     * @return void
     */
    public void close() {
        try {
            if (conn != null) {
                conn.close();
                System.out.println("Closed database connection successfully.");
            }
        } catch (SQLException e) {
            System.out.println("Error closing database connection: " + e.getMessage());
        }
    }
 
}
 
 
 
import static org.junit.jupiter.api.Assertions.*;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
 
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.Spy;
 
import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.Mockito.*;
 
 
class DatasourceTest {
 
 
    @Test
    void exceptionIsThrownIfHRDatabaseConnectionFails() throws SQLException {
        //Datasource testDatasource = new Datasource();
        //assertThrows(SQLException.class, () -> {testDatasource.open();});
        //TODO come back to this to mock connection
        Datasource testDatasource = mock(Datasource.class);
        DriverManager testDriverManager = mock(DriverManager.class);
        when(testDriverManager.getConnection(Datasource.CONNECTION_STRING, Datasource.DB_USERNAME, Datasource.DB_PASSWORD)).thenReturn(null);
        assertThrows(SQLException.class, () -> {testDatasource.open();});
    }
 
    @Test
    void exceptionIsThrownIfConnectionIsNullDuringClose() throws SQLException {
        Datasource testDatasource = new Datasource();
        DriverManager testDriverManager = mock(DriverManager.class);
        when(testDriverManager.getConnection(Datasource.CONNECTION_STRING, Datasource.DB_USERNAME, Datasource.DB_PASSWORD)).thenReturn(null);
    }
}

Answer 1

许多开发人员可能会认为此测试没有意义，但在某些情况下，您可能希望测试连接在使用后是否已成功关闭（例如：如果您发现由于程序超出最大连接数而发生错误）对于给定的资源，TDD 鼓励您添加针对此错误修复的测试）。为了做到这一点

1. 通过添加测试来设计方法接口并使其失败（DatasetTest.java 类）：

   public void whenDatasetClosed_closeReturnsTrue() {
      //安排
      //创建数据集类的新数据集实例
      数据集 dataset = new Dataset();
   
      //行为
      数据集.close();
   
     //断言
     assertTrue(dataset.isClosed());
   }
   

2. 使 conn 成为 Dataset 类的属性

3. 在 Dataset 类中实现 close() 方法

4. 将 isClosed() 方法添加到公开连接状态的 Dataset 类（例如 dataset.isClosed()、Dataset.java 类）。

   public boolean isClosed() {
      返回 this.conn.isClosed();
   }
   

5. 对于连接未关闭且应返回 false 的情况，重复此操作。