Powermockito 针对方法中new 对象的模拟，以及属性中new 对象的模拟

PowerMocker 是一个功能逆天的mock 工具。

一，Powermockito 针对方法中new 对象的模拟

// 如何才能mock掉 WeChatConfigUtil 这个类，让 weChatConfigUtil.getMainApploginSwitch();这个方法返回你想要的结果
public void testA(){
    WeChatConfigUtil weChatConfigUtil = new WeChatConfigUtil();
    weChatConfigUtil.getMainAppLoginSwitch();
  }

针对上述情况

package com.ppdai.wechat.sub.business.msgsub;

import com.ppdai.wechat.sub.util.WeChatConfigUtil;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

/**
 * Created by huxuhong on 2020/7/2.
 */
//重点，要帮要mock的类（此例为weChatConfigUtil 所在的类TestC，要放到PrepareForTest中即可）
@PrepareForTest(
        {   TestB.TestC.class
        })
@RunWith(PowerMockRunner.class)
public class TestB {
    public TestB(){

    }
    class TestC{
        public void testA(){
            WeChatConfigUtil weChatConfigUtil = new WeChatConfigUtil();
            Boolean flag = weChatConfigUtil.getMainAppLoginSwitch();
            System.out.println("mock结果"+flag);
        }
    }

    @Test
    public void testTestC(){
        TestC testC = new TestC();
        WeChatConfigUtil weChatConfigUtil = PowerMockito.mock(WeChatConfigUtil.class);
        try {
            PowerMockito.whenNew(WeChatConfigUtil.class).withAnyArguments().thenReturn(weChatConfigUtil);
            PowerMockito.doReturn(Boolean.TRUE).when(weChatConfigUtil).getMainAppLoginSwitch();
            testC.testA();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行结果

二，如何解决属性中new 对象的模拟

public class TestB {
    public TestB(){

    }
    class TestC{
       //如何mock掉属性中new 对象（此例为WechatConfigUtil weChatConfigUtil = new WechatConfigUtil,让 weChatConfigUtil.getUserInfoApiUrl 能获取到指定的值）
        WeChatConfigUtil weChatConfigUtil = new WeChatConfigUtil();
        public void testA(){
            String t = weChatConfigUtil.getUserInfoApiUrl();
            System.out.println("mock结果"+t);
        }
    }

　　

针对上述情况

public class TestB {
    public TestB(){

    }
    class TestC{
        //如果熟悉修饰为pubilc final static WechatConfigUtil,那么就需要和上面的例子一样要配置@PrepareForTest
        WeChatConfigUtil weChatConfigUtil = new WeChatConfigUtil();
        public void testA(){
            String t = weChatConfigUtil.getUserInfoApiUrl();
            System.out.println("mock结果"+t);
        }
    }

    @Test
    public void testTestC(){
        TestC testC = new TestC();
        WeChatConfigUtil weChatConfigUtil = PowerMockito.mock(WeChatConfigUtil.class);
        try {
            Field weChatConfigUtilField =  testC.getClass().getDeclaredField("weChatConfigUtil");
            weChatConfigUtilField.setAccessible(Boolean.TRUE);
            weChatConfigUtilField.set(testC,weChatConfigUtil);
            PowerMockito.doReturn("testpc").when(weChatConfigUtil).getUserInfoApiUrl();
            testC.testA();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

　　运行结果

三，引入Powermock的时候注意和mockito的版本匹配问题

  Powermock 使用过程中遇到的坑

   ①，使用Powermock mock 静态方法时，提示下面错误

        org.mockito.exceptions.misusing.NotAMockException: Argument should be a mock, but is: class java.lang.Class

处理方式：版本问题，修改为  mockito 2.25.0，powermock 2.0.2，

        issue https://github.com/powermock/powermock/issues/992#ref-commit-3479902

mockito 2.25.0和powermock 2.0.2