一、创建一个Maven项目

二、在Maven项目中添加JUnit依赖

在pom.xml中添加JUnit依赖

 <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

三、创建测试类

1.创建要被测试的类：

package com.xxx.junit;
public class Calculator {
    private static  int result;
    public Calculator(int n){
        result=n;
    }
    public int add(int n){
        return   result=result+n;
    }
    public void substract(int n){
        result=result-1;
        //Bug：正确的应该是 result=result-n
    }
    public void multiply(int n){
        //bug:此方法未实现
    }
    public void  divide(int n){
        result=result/n;
        //Bug:未做非零校验
    }
     public void square(int n){
        result=n*n;
     }
     public void squareRoot(int n){
         for(;;);
         //Bug:死循环
     }
     public void clear(){
        result=0;
     }
     public int getResult(){
        return  result;
     }

    public static void main(String[] args) {
        Calculator calculator=new Calculator(0);
        int result=calculator.add(3);
        if(result==3){
            System.out.println(result);
        }else{
            System.out.println("failure!");
        }
    }
}

2.创建测试类

package com.xxx.junit;

import junit.framework.TestCase;

public class CalculatorTest extends TestCase {
    Calculator calculator=new Calculator(0);
    public void testAdd() {
      calculator.add(3);
    }

    public void testSubstract() {
        calculator.substract(4);
    }

    public void testMultiply() {
        calculator.multiply(6);
    }

    public void testDivide() {
        calculator.divide(0);
    }

    public void testSquare() {
        calculator.square(4);
    }

   /* public void testSquareRoot() {
        calculator.squareRoot(4);
    }*/

    public void testClear() {
        calculator.clear();
    }

    public void testGetResult() {
        calculator.getResult();
    }
}

测试结果