Android单元测试系列-Mock之PowerMock

Posted 2022-04-26 Chris_166

Android单元测试系列(3)-Mock之Mockito_Chris_166的博客-CSDN博客

Android单元测试系列(1)-开篇_Chris_166的博客-CSDN博客

这两篇中已经分别介绍过Mockito的使用和局限性，本篇将介绍PowerMock，用来扩展Mockito功能，弥补其局限性(Mockito不能mock private、static方法和类，一些版本不能mock final方法和类)，同时PowerMock还增加了很多反射方法来修改静态和非静态成员等。

一、官网

PowerMock · GitHub

GitHub - powermock/powermock: PowerMock is a Java framework that allows you to unit test code normally regarded as untestable.

https://github.com/powermock/powermock/wiki/Mockito

PowerMock是依赖Mockito的，所以使用时要同时引入，且版本也必须一一对应。

PowerMock跟Mockito的版本对应关系如下：

二、Demo示例 

这里Demo按照Mockito 2.8.9，PowerMock 1.7.x来搭配。

// Gradle依赖

dependencies 

    implementation 'androidx.appcompat:appcompat:1.3.1'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.1'

    testImplementation 'junit:junit:4.+'
    testImplementation 'org.mockito:mockito-core:2.8.9'

    testImplementation "org.powermock:powermock-api-mockito2:1.7.1" // 这个mockito2必须引入，否则的话会找不到PowerMockito类
    testImplementation "org.powermock:powermock-module-junit4:1.7.1"
    testImplementation 'org.powermock:powermock-core:1.7.1'


    // androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    //androidTestImplementation "org.mockito:mockito-android:4.4.0"

// 被测试的代码

package com.fanff.unittestdemo.junitdemo;

public class Calculator 
    public int addExact(int x, int y) 
        return x + y;
    

    public int subtractExact(int x, int y) 
        return x - y;
    

    public int multiplyExact(int x, int y) 
        return x * y;
    

    // TODO: zero case
    public int intDivide(int x, int y) 
        if (y == 0) 
            return dealZeroCase();
         else 
            return x / y;
        
    

    private int dealZeroCase() 
        return 0;
    

// 测试代码

需求：测试intDivide()方法中是否有调用到dealZero()方法

package com.fanff.unittestdemo.mockdemo;

import com.fanff.unittestdemo.junitdemo.Calculator;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.mockito.Mockito.times;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Calculator.class)
public class CalculatorMockTest 
    @Test
    public void testIntDivide() 
        Calculator calculator = Mockito.spy(Calculator.class);
        calculator.intDivide(1, 0);
    

    @Test
    public void testPrivateIntDivideMethod() throws Exception 
        Calculator calculatorPowermockObj = PowerMockito.spy(new Calculator());
        calculatorPowermockObj.intDivide(1, 0);
        PowerMockito.verifyPrivate(calculatorPowermockObj, times(1)).invoke("dealZeroCase"); // Pass
    

这里说明几点：

1.  @RunWith(PowerMockRunner.class) ：这里使用的Runner是PowerMockRunner，这样就可以与Mokito兼容了，即Mokito里的方法在这里也都是可以正常使用的；

2. @PrepareForTest(Calculator.class)：务必记得加上这个PrepareForTest的注解，否则进行verify测试的时候怎么测试都是pass的，如下没有写这个注解，verifyPrivate()怎么测试都是pass：

@RunWith(PowerMockRunner.class)
// @PrepareForTest(Calculator.class)
public class CalculatorMockTest 
    @Test
    public void testPrivateIntDivideMethod() throws Exception 
        Calculator calculatorPowermockObj = PowerMockito.spy(new Calculator());
        calculatorPowermockObj.intDivide(8, 8);
        // 如下测试，预期应该是fail的，但是居然实际测试为pass，因为没有加注解@PrepareForTest(Calculator.class)
        PowerMockito.verifyPrivate(calculatorPowermockObj, times(6)).invoke("dealZeroCase");
    

三、PowerMock常用的测试方法

主要来看看PowerMock相对Mockito扩展的几点：private、final、static.

1. Private

// 被测试的类

package com.fanff.unittestdemo.junitdemo;

import java.util.ArrayList;
import java.util.List;

/**
 * 用来做Powermock的测试.
 * 方法名/类定义/魔数都是为了简单随意写的，仅仅只是用来介绍每种mock手段而已
 */
public class Person 
    private String mName;
    private final List<String> mAddressList = new ArrayList<>();
    private School mInnerSchoolObj;

    public Person(String name) 
        mName = name;
    

    public void modifyName(String name) 
        System.out.println("[public fun]++setName enter, name = " + name);
        modifyInnerName(name);

    

    public String getName() 
        return mName;
    

    public void addAddressList(String address) 
        mAddressList.add(address);
    
    public void addInnerAddressList(String innerAddr) 
        mAddressList.add(innerAddr);
    

    public List<String> getAllAddress() 
        return mAddressList;
    

    public String getSchoolNo() 
        return mInnerSchoolObj.getNo();
    

    public int getModifyInfoTimes(String info) 
        return getInnerModifyInfoTimes(info) + 2;
    
    
    private int getInnerModifyInfoTimes(String info) 
        return 1;
    
    private void modifyInnerName(String name) 
        mName = name;
        System.out.println("[private fun]setInnerName enter, finally set name = " + mName);
    

    public static class School 
        private String no;// 学号
        public void setNo() 
        
        public String getNo() 
            return no;
        
    

1.1 私有变量

package com.fanff.unittestdemo.mockdemo;

import com.fanff.unittestdemo.junitdemo.Person;

import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.powermock.api.support.membermodification.MemberModifier;
import org.powermock.reflect.Whitebox;

import java.util.List;

public class PersonTest 

    private Person mPerson;
    @Before
    public void setUp() throws Exception 
        mPerson = new Person("Chris");
    

    @After
    public void tearDown() throws Exception 
        mPerson =null;
    

    /**
     * 访问私有成员
     */
    @Test
    public void testGetPrivateMemberValue() 
        / 读取 

        String name = Whitebox.getInternalState(mPerson, "mName");
        Assert.assertEquals("Chris", name);

        mPerson.addAddressList("Wuhan");
        mPerson.addAddressList("Shenzhen");
        List<String> list = Whitebox.getInternalState(mPerson, "mAddressList");
        Assert.assertEquals(2, list.size());
        Assert.assertEquals("Shenzhen", list.get(list.size()-1));
        / 读取 

        / 两种修改私有成员的方法 
        Whitebox.setInternalState(mPerson, "mName", "FanFF");
        Assert.assertEquals("FanFF", mPerson.getName());

        try 
            MemberModifier.field(Person.class, "mName").set(mPerson, "FanFF_166");
         catch (Exception e) 
        
        Assert.assertEquals("FanFF_166", mPerson.getName());
        / 修改 
    

1. 读取私有变量使用Whitebox.getInternalState()方法；
2. 修改私有变量，可以有如下两种方法：
(1) Whitebox.setInternalState()
(2) MemberModifier.field()

1.2 私有方法

package com.fanff.unittestdemo.mockdemo;

import com.fanff.unittestdemo.junitdemo.Person;

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;


import static org.mockito.ArgumentMatchers.anyString;
import static org.mockito.Mockito.times;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Person.class)
public class PersonTest 
    /**
     * 访问私有成员方法
     */
    @Test
    public void testPrivateMethod() throws Exception 
        / Verify私有方法 //
        Person personMockObj = PowerMockito.mock(Person.class);
        personMockObj.getModifyInfoTimes("school");
        PowerMockito.verifyPrivate(personMockObj, times(0)).invoke("getInnerModifyInfoTimes", anyString());

        Person personSpyObj = PowerMockito.spy(new Person("Chris"));
        personSpyObj.getModifyInfoTimes("school");
        PowerMockito.verifyPrivate(personSpyObj, times(1)).invoke("getInnerModifyInfoTimes", anyString());
    

PowerMockito的Verify需要用@PrepareForTest之前已经说过了

2. Final

3. Static

//待续