EasyMock Test SQL Query

EasyMock

EasyMock 是一個在單元測試時，用來模擬物件，模擬物件預期行為並加以驗證。

例如 使用 SQL Query 傳回一個 List
Main.java

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

public class Main {

 public List query(Connection conn) throws SQLException {
  List list = new ArrayList();
  PreparedStatement ps = conn.prepareStatement("select user from user");
  try {
   ResultSet rs = ps.executeQuery();
   try {
    while(rs.next()) {
     list.add(rs.getString(1));   
    }
   } finally {
    rs.close();
   }
  } finally {
   ps.close();
  }
  return list;
 }

}

若要測試此程式，原本要連 database 建立 table 和 data
使用 EasyMock 就可不連 database 簡化測試
MainTest.java

import static org.easymock.EasyMock.createControl;
import static org.easymock.EasyMock.expect;
import static org.easymock.EasyMock.matches;
import static org.junit.Assert.assertEquals;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;

import org.easymock.IMocksControl;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;


public class MainTest {
 
 private Main main;

 @Before
 public void setUp() throws Exception {
  main = new Main();
 }

 @After
 public void tearDown() throws Exception {
  main = null;
 }

 @Test
 public void testQuery() throws SQLException {
  
  IMocksControl control = createControl();
  // 建立模擬物件
  Connection conn = control.createMock(Connection.class);
  PreparedStatement ps = control.createMock(PreparedStatement.class);
  ResultSet rs = control.createMock(ResultSet.class); 
  // 模擬物件預期行為
  expect(conn.prepareStatement(matches("select user from user"))).andReturn(ps);
  expect(ps.executeQuery()).andReturn(rs);
  expect(rs.next()).andReturn(true);
  expect(rs.getString(1)).andReturn("root");
  expect(rs.next()).andReturn(true);
  expect(rs.getString(1)).andReturn("tester");
  expect(rs.next()).andReturn(false);
  rs.close();
  ps.close();
  // 錄製完成，切到 replay 狀態
  control.replay();
  // 調用方法
  List expected = Arrays.asList(new String[]{"root", "tester"});
  
  List result = main.query(conn);
  assertEquals(expected, result);
  // 驗證
  control.verify();
 }

}