Mockito Hello World
项目配置
IDE是Intellij IDEA,用gradle配置项目.
新建一个Java项目,gradle中需要有这个:
repositories { jcenter() }
dependencies { testCompile "org.mockito:mockito-core:1.+" }
单元测试用JUnit 4,所以gradle文件如下:
apply plugin: ‘java‘
apply plugin: ‘idea‘
sourceCompatibility = 1.5
version = ‘1.0‘
repositories {
mavenCentral()
jcenter()
}
dependencies {
testCompile group: ‘junit‘, name: ‘junit‘, version: ‘4.11‘
testCompile "org.mockito:mockito-core:1.8.5"
}
写好之后在命令行执行:gradle idea
相关的包就会下载好,并出现在这里:
Hello World程序
想着写一个Hello World说明一下Mockito怎么用,结果写着写着就写复杂了.
先看代码:
package com.mengdd.examples.mockito;
public class HelloWorld {
private MyRobot mRobot;
public MyRobot getRobot() {
return mRobot;
}
public void setRobot(MyRobot robot) {
this.mRobot = robot;
}
/**
* This is the method we want to test.
* When there is an robot, this method return the robot‘s information
* otherwise, return some sorry text
*/
public String sayHello() {
MyRobot robot = getRobot();
if (null != robot) {
return robot.getSomeInfo();
}
return "No robot here, sorry!";
}
/**
* MyRobot class
*/
public static class MyRobot {
/**
* Get some information from somewhere, the implementation may varies
*/
public String getSomeInfo() {
return "Hello World -- From robot";
}
}
}
这段代码里面包含了一个HelloWorld类和一个内部静态类MyRobot(我的机器人).
HelloWorld中有一个方法叫sayHello(),是我们要测的方法.
它会判断成员变量是否为空,不为空则调用其方法获取一些信息,否则返回一条提示信息.
-------------------
这里插播一下,关于内部类的介绍可以参见以前的一篇笔记:http://www.cnblogs.com/mengdd/archive/2013/02/08/2909307.html
内部静态类和内部非静态类可以类比:静态成员变量和非静态成员变量.
-------------------
测试类代码如下:
package com.mengdd.examples.mockito;
import org.junit.Test;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;
public class HelloWorldTest {
@Test
public void testSayHelloWhenThereIsRobot() throws Exception {
// We want to test the sayHello() method in the class HelloWorld.
// But we don‘t care about how MyRobot get its information.(We can treat it as external interface).
// Maybe the robot rely on many complicated things.(Although it‘s simple in this case.)
// And when the robot‘s actions change in the future, we don‘t need to change this test case.
// We can mock the MyRobot‘s action to make it simple and just test whether sayHello() can do its own work.
// Mock steps
HelloWorld.MyRobot robot = mock(HelloWorld.MyRobot.class); // Mock MyRobot class
String mockInfo = "some mock info";
when(robot.getSomeInfo()).thenReturn(mockInfo); // Set behavior for mock object
// real object
HelloWorld helloWorld = new HelloWorld();//This is the real objec we want to test
helloWorld.setRobot(robot);//set the mock robot to real object
// execute the target method we want to test
String result = helloWorld.sayHello();
// assert the result is what we want to have
assertThat(result, is(mockInfo));
}
}
因为我们要测试的是HelloWorld的sayHello()方法是否能正常工作.
我们需要假定其中robot的行为是正常的(我们并不关心robot实际上做的工作,以及它怎么做),所以这里用到了mock.
比如如果机器人的实现中要发送一个请求,我们这里就是直接mock它得到的结果,而不是真的去发这个请求.
就好像准备好了所需要的所有外部条件,看sayHello()方法的表现是否能符合我们的预期.
为了全面起见,测试了sayHello()的另一种case,这里没有用到mockito.
@Test
public void testSayHelloWhenThereIsNoRobot() throws Exception {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setRobot(null);
String result = helloWorld.sayHello();
assertThat(result, is("No robot here, sorry!"));
}
参考资料
官方文档: http://site.mockito.org/mockito/docs/current/org/mockito/Mockito.html
Mockito at github: https://github.com/mockito/mockito
可以在这里看版本号: http://mvnrepository.com/artifact/org.mockito/