本文主要介绍在android studio中进行单元测试的方式，你将了解到
1.如何在android studio中引用JUnit4
2.单元测试Demo

引用模块

然后在build.gradle中添加

compile 'com.jakewharton.espresso:espresso:1.1-r3'~~~

Demo
新建一个Calculator 测试它的方法

package com.example.news;

/**

• Created by 小新 on 2016/7/1.
  */
  public class Calculator {
  public double sum(double a, double b){
  return a+b;
  }

  public double substract(double a, double b){
  return a-b;
  }

  public double divide(double a, double b){
  return a/b;
  }

  public double multiply(double a, double b){
  return a*b;
  }

  public double addMore(double a,double b,double c){

   return a+b+c;
  

  }

}

在类名上面点击右键生成test测试类

![测试类生成截图](http://upload-images.jianshu.io/upload_images/796164-f98d82421be0796a.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![测试类名，勾选测试方法](http://upload-images.jianshu.io/upload_images/796164-5b982393d237fa2d.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
会在测试类的包中自动生成测试类

package com.example.news;

import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.*;

/**

• Created by 小新 on 2016/7/1.
  */
  public class CalculatorTest {

  @Before
  public void setUp() throws Exception {

  }

  @Test
  public void testSum() throws Exception {

  }

  @Test
  public void testSubstract() throws Exception {

  }

  @Test
  public void testDivide() throws Exception {

  }

  @Test
  public void testMultiply() throws Exception {

  }

  @Test
  public void testAddMore() throws Exception {

  }
  }

然后进行测试

package com.example.news;

import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.*;

/**

• Created by 小新 on 2016/7/1.
  */
  public class CalculatorTest1 {
  private Calculator calculator;

  @Before
  public void setUp() throws Exception {
  calculator = new Calculator();

  }

  @Test
  public void testSum() throws Exception {
  //测试sum函数，因为sum函数返回的是两个数的合为3
  //这里期望返回的值是9
  //所以会报错
  assertEquals(9d,calculator.sum(1d,2d),0);
  }

  @Test
  public void testSubstract() throws Exception {

  }

  @Test
  public void testDivide() throws Exception {

  }

  @Test
  public void testMultiply() throws Exception {

  }

  @Test
  public void testAddMore() throws Exception {

  }
  }

运行这个类，结果为报错，这个时候我们就需要修改函数了
到这里我们JUnix的简单测试就结束了