EasyMock

What is a Mock Object?

Unit testing is the testing of software units in isolation. However, most units do not work alone, but they collaborate with other units. To test a unit in isolation, we have to simulate the collaborators in the test.

A Mock Object is a test-oriented replacement for a collaborator. It is configured to simulate the object that it replaces in a simple way.

 

EasyMock has been the first dynamic Mock Object generator, relieving users of hand-writing Mock Objects, or generating code for them.

 

 

一个将被Mock：使用JDBC连接DB，得到Table Student的记录

package wei.peng.easymock;

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

/**
 * 一个用于连接DB得到数据记录的类
 * @author WPeng
 */
public class BeMockObject {
	
	public int getRecordNum(){
		int record = 0;
		Connection conn;
		Statement stmt;
		
		try {
			// Load JDBC driver
			Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
			
			// Connection
			String url =  "jdbc:mysql://MyDbComputerNameOrIP:3306/myDatabaseName";
			conn = DriverManager.getConnection(url, "wpeng", "***" ); 
			
			// Create Statement
			stmt = conn.createStatement();
			
			// Query
			String sql = "SELECT COUNT(*) FROM student";
			ResultSet rs = stmt.executeQuery(sql);
			
			while (rs.next()) {
				record = rs.getInt(1);
			}
			
			try {
				if(!conn.isClosed()){
					conn.close();
				}
			} catch (SQLException e2) {
				// TODO: handle exception
			}
		} catch (Exception e) {
			// TODO: handle exception
		} 
		return record;
	}
}

 

一个JUnit Test Case：Mock一个BeMockObject

package wei.peng.easymock;

import org.easymock.EasyMock;

import junit.framework.TestCase;

public class MainTest extends TestCase{
	
	public void testGetRecordNum(){
		int expected = 100;
		
		BeMockObject beMockObject = EasyMock.createMock(BeMockObject.class);
		EasyMock.expect(beMockObject.getRecordNum()).andReturn(100);
		EasyMock.replay(beMockObject);
		
		assertEquals(expected, beMockObject.getRecordNum());
	}
}