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[Java教程]Mockito Hello World


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 = 1.5version = '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.
@Testpublic 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

  官网: http://mockito.org/
  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/