对象在数据库单元测试中为空

Question

我有两个用 java 编写的函数，我正在尝试创建它们的单元测试。第一个功能是向数据库添加一个元素，第二个功能是通过它的 id 从数据库中获取元素。 我创建了他们的两个测试，第一个在数据库中正确插入。但是当我得到一个时，数据库似乎是空的！

enter code here
package com.example.service;

import com.example.model.City;
import org.junit.Test;

import java.sql.*;

public class DatabaseService {


public static int addCity(Connection conn, City city) {
    PreparedStatement pstmt = null;
    int i = -1;
    try {
        String sql = "INSERT INTO City " + "VALUES (?,?,?,?)";
        pstmt = conn.prepareStatement(sql);

            pstmt.setInt(1, city.getIdCity());
            pstmt.setString(2, city.getName());
            pstmt.setInt(3, city.getTouristNumber());
            pstmt.setString(4, city.getDescription());
            i = pstmt.executeUpdate();
            pstmt.close();


    } catch (SQLException se) {
        se.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (pstmt != null) pstmt.close();
        } catch (SQLException se2) {
        }
    }
    return i;
}


public static City getCity(Connection conn,int idCity) {
    PreparedStatement pstmt = null;
    City city = new City();
    try {

        String sql = "SELECT * FROM City where idCity=?";
        pstmt = conn.prepareStatement(sql);
        pstmt.setInt(1,idCity);
        ResultSet rs = pstmt.executeQuery();
        while (rs.next()) {
            city.setIdCity(rs.getInt("idCity"));
            city.setName(rs.getString("name"));
            city.setTouristNumber(rs.getInt("touristNumber"));
            city.setDescription(rs.getString("description"));
        }

        rs.close();
        pstmt.close();
    } catch (SQLException se) {
        se.printStackTrace();
    } finally {
        try {
            if (pstmt != null) pstmt.close();
        } catch (SQLException se2) {
        }
    }
    return  city;
}

}

对于连接：

enter code here
 package com.example.service;

  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.SQLException;
  import java.sql.Statement;

  public class DatabaseConnection {

private String USER;
private String PASS;
private String JDBC_DRIVER;
private String DB_URL;

public DatabaseConnection(String USER, String PASS, String JDBC_DRIVER, String DB_URL) {
    this.USER = USER;
    this.PASS = PASS;
    this.JDBC_DRIVER = JDBC_DRIVER;
    this.DB_URL = DB_URL;
}

public  Connection connect() {
    Connection conn = null;
    try {
        conn = DriverManager.getConnection(DB_URL, USER, PASS);
        Class.forName(JDBC_DRIVER);
    } catch (SQLException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    return conn;
}

public  void disconnect(Connection conn ) {
    try {
        conn.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

public void createDb(Connection conn) {
    Statement stmt = null;
    try {
        stmt = conn.createStatement();
        String sql =  "CREATE TABLE   City " +
                "(idCity INTEGER not NULL, " +
                " name VARCHAR(255), " +
                " touristNumber INTEGER, " +
                " description VARCHAR(255), " +
                " PRIMARY KEY ( idCity ))";
        stmt.executeUpdate(sql);
        stmt.close();
    } catch(SQLException se) {
        se.printStackTrace();
    } catch(Exception e) {
        e.printStackTrace();
    } finally {
        try{
            if(stmt!=null) stmt.close();
        } catch(SQLException se2) {
        }
    }
}

}

对于单元测试：

enter code here
 package com.example.service;

import com.example.model.City;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

 import java.sql.Connection;

import static org.junit.Assert.*;

public class DatabaseServiceTest {
City city;

Connection conn;
DatabaseConnection datab;
@Before
public void init(){
    datab= new DatabaseConnection("sa","","org.h2.Driver","jdbc:h2:mem:test") ;
   conn = datab.connect();
   datab.createDb(conn);
    city = new City(1,"Alger",123,"capital");



}
@Test
public void addCity() {

    assertEquals(1,new DatabaseService().addCity(conn, city));

}

@Test
public void getCity() {

    assertEquals(city.getIdCity(),new DatabaseService().getCity(conn, 1).getIdCity());
 /*   assertEquals(city.getTouristNumber(),new DatabaseService().getCity(conn, 1).getTouristNumber());
    assertEquals(city.getName(),new DatabaseService().getCity(conn, 1).getName());
    assertEquals(city.getDescription(),new DatabaseService().getCity(conn, 1).getDescription());*/
}

}

对于调试结果，我得到了这个：（第二个得到：）

enter code here
 Connected to the target VM, address: '127.0.0.1:3543', transport: 'socket'
 Java HotSpot(TM) 64-Bit Server VM warning: Sharing is only supported for boot 
 loader classes because bootstrap classpath has been appended

 java.lang.AssertionError: 
 Expected :1
 Actual   :0

at org.junit.Assert.fail(Assert.java:93)
at org.junit.Assert.failNotEquals(Assert.java:647)
at org.junit.Assert.assertEquals(Assert.java:128)
at org.junit.Assert.assertEquals(Assert.java:472)
at org.junit.Assert.assertEquals(Assert.java:456)
at com.example.service.DatabaseServiceTest.getCity(DatabaseServiceTest.java:37)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)

Disconnected from the target VM, address: '127.0.0.1:3543', transport: 'socket'

 Process finished with exit code -1

Answer 1

您可能会发现使用 Mockito 模拟数据库连接而不是使用内存数据库很有趣，原因有两个：

1. 内存中的数据库可能会在并行运行测试时引入问题
2. 由于不是同一个数据库，可能存在内存版本中不存在的特殊 SQL 功能或关键字。

看看这个，它可以帮助您了解如何使用模拟连接测试 DatabaseService： How to use mockito for testing Database connection